1-20 Protection Against Liquid Damage

7/30/2019 1-20 Protection Against Liquid Damage

1/24

September 1999Revised May 2003

Page 1 of 24

PROTECTION AGAINST EXTERIOR FIRE EXPOSURE

Table of ContentsPage

1.0 SCOPE ................................................................................................................................................... 31.1 Changes .......................................................................................................................................... 3

2.0 LOSS PREVENTION RECOMMENDATIONS ....................................................................................... 32.1 For Fire Exposure from Buildings .................................................................................................... 3

2.1.1 Construction and Location .................................................................................................... 32.2 For Fire Exposure from Yard Storage ........................................................................................... 10

2.2.1 Construction and Location .................................................................................................. 103.0 EXPOSURE FIRES (GENERAL) ......................................................................................................... 12

3.1 Exposing Building .......................................................................................................................... 123.1.1 Construction ........................................................................................................................ 123.1.2 Ventilation ............................................................................................................................ 133.1.3 Wind .................................................................................................................................... 133.1.4 Effect of Fire Department .................................................................................................... 133.1.5 Length of Wall Creating the Fire Exposure ......................................................................... 13

3.2 Exposed Building ........................................................................................................................... 133.2.1 When Not Sprinklered ......................................................................................................... 133.2.2 Construction ........................................................................................................................ 133.2.3 Protection of Openings ........................................................................................................ 133.2.4 Protection Beyond Ends of Exposing Building ................................................................... 143.2.5 Protection of Side Walls ...................................................................................................... 153.2.6 Protection when Walls at an Angle with Exposing Building ................................................ 173.2.7 Protection for Roof When Lower Than Exposing Building ................................................. 183.2.8 Protection of Walls Above Lower Exposing Building .......................................................... 18

3.3 Fire Exposure From Yard Storage ................................................................................................ 193.4 Yard Housekeeping ....................................................................................................................... 19

4.0 REFERENCES ..................................................................................................................................... 204.1 FM Global ...................................................................................................................................... 20

APPENDIX A GLOSSARY OF TERMS ...................................................................................................... 23APPENDIX B DOCUMENT REVISION HISTORY ..................................................................................... 24

List of FiguresJob Aid No. 1 for Using Tables 1 and 2. ........................................................................................................ 4Job Aid No. 2 for Yard Storage. .................................................................................................................. 10Fig. 1. Exposed building walls are longer than exposing walls. .................................................................. 14Fig. 2. Protection for side walls of exposed building. .................................................................................. 16Fig. 3. Protection for exposed building when walls are at an angle ( ) with exposing building. ............... 18Fig. 4a. Protection for exposed buildings higher than the exposing building. ........................................... 20

Fig. 4b. Protection of walls above the exposure (English units). ................................................................ 21Fig. 4c. Protection of walls above the exposure (SI Units). ........................................................................ 22

List of TablesTable 1a. Determination of Separation Distance, or Exposure Category for Use in Table 2 When

Exposed Wall is 1, 2 or 3 hour ...................................................................................................... 5Table 1b. Determination of Separation Distance, or Exposure Category for Use in Table 2 When

Exposed Wall is Category C ......................................................................................................... 6

FM GlobalProperty Loss Prevention Data Sheets 1-20

2003 Factory Mutual Insurance Company. All rights reserved. No part of this document may be reproduced,stored in a retrieval system, or transmitted, in whole or in part, in any form or by any means, electronic, mechanical,photocopying, recording, or otherwise, without written permission of Factory Mutual Insurance Company.

Valid Through January, 2004


2/24

Table 1c. Determination of Separation Distance, or Exposure Category for Use in Table 2 WhenExposed Wall is Category D ......................................................................................................... 7

Table 2. Multipliers for Space Separation ...................................................................................................... 8Table 3. Levels of Passive Protection, P .................................................................................................... 15Table 4. Protection for Longer Exposed Walls ............................................................................................ 15

Table 5. Multipliers for Non-Parallel Exposures .......................................................................................... 17

1-20 Protection Against Exterior Fire ExposurePage 2 FM Global Property Loss Prevention Data Sheets

2003 Factory Mutual Insurance Company. All rights reserved.



3/24

1.0 SCOPE

This data sheet provides guidelines for recognizing and dealing with a potential fire exposure from one ormore existing buildings or yard storage. Another objective is to enable designers and architects to avoidexposure problems when laying out new buildings.

This data sheet does not discuss fire exposure from flammable liquid transmission pipelines. For discussionon that subject, refer to Data Sheet 7-32, Flammable Liquid Operations .

This data sheet generally considers the fire exposure to be on adjacent property, where control of the exposuremay be outside the influence of the owner of the exposed building. The data sheet may also be used, if appli-cable, when the fire exposure and the exposed building are on the same insured property and the expos-ing building is not adequately sprinklered. The latter case is infrequent. Provision of automatic sprinklers inthe exposing buildings would greatly reduce the hazard. This data sheet assumes that unimpaired sprinklerprotection is available in the exposed building. This data sheet does not apply to Maximum Foreseeable Loss(MFL) space separations, (Data Sheet 1-22, Criteria for Maximum Foreseeable Loss Fire Walls and Space Separation ), since MFL space separation assumes an impairment to the sprinkler protection.

This document should be used for exposing flammable liquids storage buildings that are unsprinklered. Referto Data Sheet 7-29, Flammable Liquid Storage in Portable Containers for separation of flammable liquidyard storage pads, and separation and protection of detached, sprinklered flammable liquid storage buildings.

For the recommended separation from storage tanks in the yard, refer to Data Sheet 1-57, Rigid Plastic Building Materials or Data Sheet 7-88, Storage Tanks for Flammable and Combustible Liquids .

This document is not intended to be used for exposure protection from another tenant within the samemulti-tenanted building. For such situations refer to Data Sheet 1-19, Fire Walls, Subdivisions and Draft Curtains or Data Sheet 1-22.

For a description of storage commodities, see Data Sheet 8-1, Commodity Classification .

1.1 Changes

May 2003. This revision of the document has been reorganized to provide a consistent format.

2.0 LOSS PREVENTION RECOMMENDATIONS

2.1 For Fire Exposure from Buildings

2.1.1 Construction and Location

2.1.1.1 When the exposing building is sprinklered, and it can be established that the sprinkler protection inthe exposing building is adequate and reliable, no fire exposure is considered to exist.

2.1.1.2 Exposed buildings should be separated from exposures according to Tables 1 and 2. Job Aid No. 1should be used to facilitate the use of these tables.

If an existing building is nearer to the exposure than the recommended separation distances determinedfrom Tables 1 and 2, passive protection such as the provision of a fire-rated wall over the outside face, oractive protection such as the provision of automatic outside sprinklers will provide the needed protection. Forexample, the provision of two layers of 5 8 in. (15 mm)-thick Type X gypsum board faced with steel panels,applied to the wall exterior will provide 1-hour fire resistance. For various combinations of protection usingmasonry, see Data Sheet 1-21, Fire Resistance of Building Assemblies .

The categories of construction materials used for Table 1 are not based on the combustibility of a materialonly. Consideration is also given to the ease of ignition, and the potential for burn through or melting as itrelates to an exposing building giving off radiant heat and an exposing building resisting it.

CAT. A. Category A materials include steel faced panels or cementitious panels, with or without noncombus-tible insulation (as defined in Section 1.1). It also includes FM Approved (see Appendix A for definition), steelfaced class 1 insulated panels on steel framing; and EIFS assemblies using noncombustible insulation orApproved class 1 insulation over gypsum board on steel framing.

CAT. B. Category B materials include painted, unpainted or asphalt shingled wood; rigid plastic panels suchas fiberglass reinforced plastic (FRP) or polyvinyl chloride (PVC); any aluminum panels; EIFS assemblies

Protection Against Exterior Fire Exposure 1-20FM Global Property Loss Prevention Data Sheets Page 3




4/24

using EPS insulation or a combustible sheathing board; non-Approved insulated steel panels; or other assem-blies supported by wood framing that is unprotected on the interior.

CAT. C. Category C materials include Approved Class 1 insulated, steel or aluminum faced sandwich panelswith thermoset plastic insulation; EIFS assemblies having noncombustible insulation and gypsum board

sheathing; and aluminum or steel panels that are uninsulated or insulated with noncombustible insulationsuch as glass fiber, mineral wool, or expanded glass. It also includes cementitious panels or shingles oversteel or wood.

CAT D. Category D materials include painted or unpainted wood, metal faced wall assemblies withthermoplastic insulation such as expanded or extruded polystyrene, or polyethylene; metal faced panels withthermoset insulation, such as polyurethane or polyisocyanurate foam, which are not Approved; all rigid plasticpanels such as FRP or PVC; and EIFS assemblies having EPS insulation or a combustible sheathing board.

1. For additional details on exposing construction, refer to Appendix A and 3.1.1.

2. For additional details on the exposing occupancy, refer to Appendix A.

3. For additional details on the exposed wall construction, refer to Appendix A and 3.2.2.

Job Aid No. 1 for Using Tables 1 and 2.

1. Details include wall and roof construction type, percent window openings (include door openings if doorconstruction has a lesser fire rating than the wall), exposing wall height and width.

2. Details include exposed wall construction type, details of unprotected openings and roof construction type.





5/24

Table 1a. Determination of Separation Distance, or Exposure Category for Use in Table 2 When Exposed Wall is 1, 2 or 3 hour

Exposed Wall Exposing Building Percent Unprotected Openings in Exposing Wall

Construction Wall Roof Occupancy Category for Use in Table 2 or Minimum Separation Required

3 hr SFR NC, Class 1orCombustible

Light,Ordinaryor High

DNANo minimum separation required

3 hr Cat. A NC, Class 1or

Combustible

Light orOrdinary

DNA

No minimum separation required

3 hr Cat. A NC, Class 1or

Combustible

High 70% 70%


6/24

Table 1b. Determination of Separation Distance, or Exposure Category for Use in Table 2 When Exposed Wall is Category C

CAT. C.: Category C materials include FM Approved Class 1 insulated, steel or aluminum faced sandwich panels with thermoset plastic insulation; EIFS assemblies having noncombustible insulation and gypsum board sheathing;

and aluminum or steel panels that are uninsulated or insulated with noncombustible insulation such as glass fiber,mineral wool, or expanded glass. It also includes cementitious panels or shingles over steel or wood.


Construction Wall Roof Occupancy Category for Use in Table 2 or Minimum Separation Required Cat. C SFR NC or

Class 1Light 0% , 40% 60% 80% 100%

1 2 3 4Cat. C SFR NC or

Class 1Ordinary 0% , 30% 50% 80% 100%

1 2 3 4Cat. C SFR NC, Class 1

orCombustible

High 0% , 25% 50% 80% 100%

6 7 8 9

Cat. C SFR Combustible Light 0% , 30% 50% 80% 100%1 2 3 4

Cat. C SFR Combustible Ordinary 20% 40% 60% 80% 100%1 2 3 4 5

Cat. C Cat. A NC orClass 1 Light 0% , 25% 50% 70% 100%1 2 3 4Cat. C Cat. A NC or

Class 1Ordinary 0% , 10% 30% 60% 100%

1 2 3 4Cat. C Cat. A NC, Class 1

orCombustible

High 0% , 5% 30% 60% 100%

6 7 8 9

Cat. C Cat. A Combustible Light 0% , 10% 30% 60% 100%1 2 3 4

Cat. C Cat. A Combustible Ordinary 0% 20% 40% 60% 100%1 2 3 4 5

Cat. C Cat. B NC orClass 1

Light DNA6

Cat. C Cat. B NC orClass 1

Ordinary DNA7

Cat. C Cat . B NC, Class 1or

Combustible

High DNA

9

Cat. C Cat. B Combustible Light orOrdinary

DNA7

For explanation of Combustible, Stable Fire Resistive (SFR), Noncombustible (NC), or Class 1, see Appendix A.





7/24

Table 1c. Determination of Separation Distance, or Exposure Category for Use in Table 2 When Exposed Wall is Category D

CAT. D: Category D materials include painted or unpainted wood, metal faced wall assemblies with thermoplastic insulation such as expanded or extruded polystyrene, or polyethylene; metal faced panels with thermoset insulation, such

as polyurethane or polyisocyanurate foam, which are not FM Approved; all rigid plastic such as FRP or PVC; and EIFS assemblies having EPS insulation or a combustible sheathing board.


Construction Wall Roof Occupancy Category for Use in Table 2 or Minimum Separation Required Cat. D SFR NC or

Class 1Light 0% 25% 40% 50% 60% 80% 100%

1 2 3 4 5 6 7Cat. D SFR NC or

Class 1Ordinary 0% 10% 20% 30% 50% 60% 80% 100%

3 4 5 6 7 8 9 10Cat. D SFR NC, Class 1

orCombustible

High 0% ,15% 40% 60% 80% 100%

9 10 11 12 13

Cat. D SFR Combustible Light orOrdinary

0% 10% 20% 30% 50% 60% 80% 100%3 4 5 6 7 8 9 10

Cat. D Cat. A NC orClass 1

Light 0% 20% 30% 40% 60% 100%2 3 4 5 6 7

Cat. D Cat. A NC, Class 1 orCombustible Combustible

Ordinary

Light

0% 10% 30% 40% 60% 100%5 6 7 8 9 10

Cat . D Cat. A NC, Class 1or

Combustible

High 0% 40% 60% 100%

10 11 12 13

Cat. D Cat. B NC or Class1

Light DNA10

Cat. D Cat. B NC or Class1

Ordinary DNA11

Cat . D Cat. B NC, Class 1or

Combustible

High DNA

13

Cat. D Cat. B Combustible Light DNA11

Cat. D Cat. B Combustible Ordinary DNA12

For explanation of Combustible, Stable Fire Resistive (SFR), Noncombustible (NC), or Class 1, see Appendix A.





8/24

Table 2. Multipliers for Space Separation

Category

Number

L/H or H/L of Exposing Wall (whichever is greater than 1.0)L = length in ft (m), H = height in ft (m)

1.0 1.3 1.6 2.0 2.5 3.2 4. 5. 6. 8. 10. 13. 16. 20. 25. 32. 40or

higherSeparation Multiplier

(multiply by lesser dimension, add 5 feet, (1.5 m) to obtain building-to-building separation)1 0.36 0.40 0.44 0.46 0.48 0.49 0.50 0.51 0.51 0.51 0.51 0.51 0.51 0.51 0.51 0.51 0.512 0.60 0.66 0.73 0.79 0.84 0.88 0.90 0.92 0.93 0.94 0.94 0.95 0.95 0.95 0.95 0.95 0.953 0.76 0.85 0.94 1.02 1.10 1.17 1.23 1.27 1.30 1.32 1.33 1.33 1.34 1.34 1.34 1.34 1.344 0.90 1.00 1.11 1.22 1.33 1.42 1.51 1.58 1.63 1.66 1.69 1.70 1.71 1.71 1.71 1.71 1.715 1.02 1.14 1.26 1.39 1.52 1.64 1.76 1.85 1.93 1.99 2.03 2.05 2.07 2.08 2.08 2.08 2.086 1.22 1.37 1.52 1.68 1.85 2.02 2.18 2.34 2.48 2.59 2.67 2.73 2.77 2.79 2.80 2.81 2.817 1.39 1.56 1.74 1.93 2.13 2.34 2.55 2.76 2.95 3.12 3.26 3.36 3.43 3.48 3.51 3.52 3.538 1.55 1.73 1.94 2.15 2.38 2.63 2.88 3.13 3.37 3.60 3.79 3.95 4.07 4.15 4.20 4.22 4.249 1.82 2.04 2.28 2.54 2.82 3.12 3.44 3.77 4.11 4.43 4.74 5.01 5.24 5.41 5.52 5.60 5.64

10 2.05 2.30 2.57 2.87 3.20 3.55 3.93 4.33 4.74 5.16 5.56 5.95 6.29 6.56 6.77 6.92 7.0111 2.26 2.54 2.84 3.17 3.54 3.93 4.36 4.82 5.30 5.80 6.30 6.78 7.23 7.63 7.94 8.18 8.3412 2.63 2.95 3.31 3.70 4.13 4.61 5.12 5.68 6.28 6.91 7.57 8.24 8.89 9.51 10.05 10.50 10.8413 2.96 3.32 3.72 4.16 4.65 5.19 5.78 6.43 7.13 7.88 8.67 9.50 10.33 11.15 11.91 12.59 13.15

Additional comments regarding the use of Table 2 are as follows:

1. If the wall and roof of the exposing building are stable fire resistive (SFR) and there are no wall openingsor roof openings (such as skylights or heat and smoke vents), no minimum separation is needed.

2. If the wall of the exposed building is asphalt shingle over wood or asphalt coated metal (ACM), increasethe space separation recommended for Category D exposed walls by 25%.

3. If adequate horizontal or vertical fire cutoffs exist in the exposing building, they may be used to reducethe L/H (length/height) ratio and lesser exposure dimension as applicable.

4. It is reasonably accurate to interpolate between aspect ratios.

5. If the exposed construction is of a type noted in Category D, asphalt shingle or ACM, the space separa-tion need not exceed 300 ft (91 m), regardless of other parameters in Table 1 and Table 2. For all other typesof exposed construction, the space separation need not exceed 200 ft (61 m).

6. Where the occupancy is light or ordinary and the walls, roof and interior finish are all noncombustible,the height of the storage can be used to determine the L/H ratio.

7. For light occupancy classifications with combustible interior finish, increase the occupancy classificationby one level. This applies to buildings that have combustible ceilings, combustible interior walls or woodfloors.

8. For exposing buildings that are multistory with wood floors, use high hazard exposure.

9. For existing buildings where the exposing building is considerably longer than the exposed building, Lmay be effectively taken to be four times the actual separation distance if that distance is less than the actuallength of the exposing building.

While this method may be used for proposed installations, it may involve several iterations if the originallyproposed space is less than needed. In each successive iteration the effective length must be increased untilthe proposed space is at least equal to the needed space. A more simplified approach is to use the entirelength of the exposing building which may yield a more conservative answer.





9/24

2.1.1.3 Where the exposure and space separation is such that a 2- or 3-hour fire rated exposed wall is needed,window openings need to be filled in with masonry or protected by automatic closing, shutters comparablein fire rating to that of the wall.Approved minimum 1 1 2-hour fire rated doors that are normally closed (equippedwith a door closure) or automatic closing and latched should be provided in door openings (blank steel doorssuitable for a class D opening). If the space separation provided is at least 5 ft (1.5 m), an alternative is to

provide listed (tested by a nationally recognized laboratory) fire rated glass (such as ceramic glass, glass blockor wired glass that has passed a hose stream test, see Data Sheet 1-21) and automatic window sprinklers.

2.1.1.4 Where the exposure and space separation is such that a 1-hour fire rated exposed wall is needed,listed minimum 3 4 hour fire rated glass should be installed in window openings in accordance with arealimitations of the listing. Combustibles should be kept away from the inside of the exposed windows by adistance at least equal to the largest dimension of the window.

Door openings should be protected by Approved, minimum 3 4-hour fire rated fire doors (suitable for a Class Eexterior opening). The doors should be normally closed (self-closing) or automatic closing, and latched.

2.1.1.5 Where the exposed wall needs to be of a type outlined in Category C of Table 1, windows shouldbe tempered glass.

Where the exposure and space separation is such that a Category C exposed wall is needed, doors on theexposed wall should be normally closed (self-closing) or automatic closing, and latched steel doors that areeither blank or have vision panels made of fire rated or tempered glass.

2.1.1.6 Where window or outside sprinklers are needed, they should be installed according to Data Sheet2-8N, NFPA 13 Standard for the Installation of Sprinkler Systems 1996 Edition . They should be arranged forautomatic operation.

Window sprinklers can be considered an alternative to upgrading the type of glass, except where 2-or-3 hourfire rated exposed walls are needed and listed fire rated glass and sprinklers must be provided.

2.1.1.7 Combustible materials should not be stored or used within the separation space. When combus-tibles are stored within a space between buildings, adequate space separation should be provided betweenthe yard storage and the buildings on both sides (see Section 3.0). The storage of fuels or chemicals nearthe interior side of an exposed wall should be avoided.

2.1.1.8 Exposed roof coverings, or portions thereof, should have a Class A roof system, based on the

American Society for Testing and Materials (ASTM) test standard E 108, in the following areas:a) Where they are within a distance of 150 ft (46 m) from a building constructed with a wood roof, wallsor floors, or combustible yard storage.

b) On the entire roof of buildings subdivided by Maximum Foreseeable Loss (MFL) fire walls. See DataSheet 1-22 for an explanation and details of additional protection that may be needed for the roof.

c) Where the occupancy below the roof is susceptible to water, smoke or other nonthermal damage.

When the roof of the exposed building is lower than the exposing building, protection for the roof shouldbe provided within 50 ft (15 m) from the exposure as outlined below:

a) For built-up roof coverings (BUR), place a minimum of 4 lb/ft 2 (20 kg/m 2 ) of pea gravel in a flood coatof hot asphalt or coal tar.

b) For single-ply roof coverings, large stone ballast or concrete paver blocks should be provided as outlined

in Data Sheet1-29, Roof Deck Securement and Above-Deck Roof Components .2.1.1.9 When any significant exterior fire exposure exists, the fire department should conduct prefire planningtaking into consideration protection of the exposed property.

2.1.1.10 Exposing buildings that are of noncombustible or fire resistive construction and that are vacant orcontain only noncombustible contents do not necessitate space separation or other protection for adjacentbuildings.

2.1.1.11 When the exposed wall is longer than the exposing wall, protection beyond the end(s) of the exposingbuilding should be provided according to Section 3.2.4.

2.1.1.12 When the exposed wall is shorter than the exposing wall, protection for the end walls of the exposedbuilding should be provided according to Section 3.2.5.





10/24

2.1.1.13 When the exposed building is not parallel to the exposing wall, protection for the exposed wallsshould be provided according to Section 3.2.6.

2.1.1.14 When the exposed wall is higher than the exposing wall, and the separation distance between thetwo buildings is less than needed according to Recommendation 2.1.1.2, protection for the higher portions

of the exposed wall should be provided according to Section 3.2.8.2.1.1.15 If a combustible (see Appendix A) canopy or overhanging eave is provided on the exposed build-ing, the separation distance between the exposing building and the outer edge of the canopy or overhangshould be based on Category D exposed construction, regardless of the type of wall construction. Alterna-tively, separation which is adequate for the wall construction is acceptable provided the combustible canopyor overhang is sheathed with a material having fire resistance at least equal to that of the wall.

2.1.1.16 In some cases the potential for non-thermal damage to the contents of an exposed building willbe significant. If so, automatic closing dampers should be provided on outside air intakes. For new construc-tion, outside air intakes should be located as close to grade level as practical.

2.1.1.17 The most likely time for a major exposure fire to occur is during the demolition of adjacent property.Precautions for such demolition operations are outlined in Data Sheet 1-0, Safeguards During Construction,Alteration and Demolition and should be followed.

2.2 For Fire Exposure from Yard Storage

Use Job Aid No. 2 to facilitate the application of recommendations in this section.

2.2.1 Construction and Location

2.2.1.1 Refer to Section 3.3 for a list of various outdoor storages that are covered by other data sheets. Usethis document to supplement those or where no other specific data sheet exists. For the exterior protec-tion of the roof systems, see Section 2.2.1.8.

Job Aid No. 2 for Yard Storage.





11/24

2.2.1.2 When large quantities of high-value products are stored in the yard, consideration should be givento a sprinklered enclosure over them. This will a) protect the products themselves from fire, and b) reduce thehazard of exposure to nearby buildings.

2.2.1.3 Yard hydrants should be provided when combustible materials are stored outside the plant buildings

(Data Sheet 3-10, Installation and Maintenance of Private Fire Service Mains and their Appurtenances ).Hydrants should be provided just outside the ends of spaces between buildings and at intervals in betweennot exceeding 300 ft (90 m).

2.2.1.4 Relocating the yard storage so that separation distances are adequate is preferable to specialexposure protection.

For ordinary or light hazard yard storage with all types of exposed walls, and for high hazard yard storagewith all types of exposed walls except Category D (Appendix A), use Tables 1 and 2 to determine neededspace separation. Treat the yard storage as an exposing building, assuming the wall and roof of the expos-ing building are a Category A type and noncombustible, respectively, with 100% openings in the exposing walland using the applicable details of the occupancy and exposed walls.

Tables 1 and 2 should not be used to determine space separation between yard storage classified as highhazard and exposed Category D walls. For such situations the following formula should be used:

(Equation 1)S = 3.07 LH

or

(Equation 2)

S = 16 H

where: S = minimum recommended space separation, ft (m)L = Length of the yard storage in the direction parallel to the exposure, ft (m)H = Height of the yard storage, ft (m)Use Equation 1 when L 24 HUse Equation 2 when L > 24 HUse Equation 1 and 2 only for yard storage of high hazard materials exposing combustible walls.

When storage is in a yard, it is reasonable to assume that the maximum length (parallel to the exposed wall)across which a fire in any commodity will burn at its maximum rate of heat release is about 400 ft (122 m).In other words, the maximum length (L) used in determining the needed separation distance is 400 ft(122 m).

Because of other factors such as re-radiation, more rapid fire spread could be expected throughout the entirefire cutoff area of a building.

Consequently, this maximum length should not be used to determine building-to-building separation.

Where adequate space separation is not available, and provision of a protected enclosure for the yard storageis not practical, provide water spray protection for the exposed building as outlined in Data Sheet 2-8N.

2.2.1.5 Unpaved yards should be mowed so that the height of grass and weeds does not exceed 4 in.(100 mm). All combustible trash should be removed from the premises.

2.2.1.6 Dumpsters (rubbish skips) should be located at least 35 ft (11 m) from exposed buildings, unlessthe exposed walls are of blank masonry or concrete construction.

2.2.1.7 Loaded trailers stored in the yard should be treated as a building separation would, taking intoconsideration the contents and construction of the trailer.

2.2.1.8 Metal chain link fencing should be provided around the yard, with an adjacent aisle space betweenit and yard storage to prevent direct access by vandals. (See Data Sheet 9-17, Protection Against Arson and Other Incendiary Fires .)





12/24

3.0 EXPOSURE FIRES (GENERAL)

When evaluating the magnitude of the exposure fire, the type of construction; area, percent wall openingsand occupancy of the exposure should be considered. Consideration should also be given to the type of walland roof exposed to the radiant heat.

Recommended separations are based on estimated portions of the exposing flame height that is unobscuredby smoke. For applications simplicity, exposing wall or storage heights are used for input.

A fire that results in ignition of or radiant heat damage to nearby buildings or other property is an exposurefire. In many large exposure fires, the origin of the fire has been on neighboring or adjoining property. Plantbuildings also have been exposed and damaged by exposure fires starting in yard storages such as lumber,roll paper, tires, plastics, etc., or in separate, unsprinklered structures. Automatic sprinklers and firefightersusually control the fire and keep it from spreading throughout the exposed building, although heat, water andsmoke damage may be considerable.

1. It is necessary to consider fire exposure protection (to buildings) from a fire in adjacent buildings or yardstorage when:

a) Separation distances are close enough so that a hazard to the exposed building is judged to exist,and

b) Any one of the exposing properties is unsprinklered, or has sprinkler protection that is inadequate oris not considered reliable.

Once a fire exposure hazard is judged to exist, guidelines in this data sheet can be used to determine if sepa-ration distances between the exposing and exposed buildings are safe for the degree of protection affordedby the construction and sprinklers in the exposed building, or if protection for the exposed building is needed.

Protection may be active, in which case water is applied directly to the exposed building during a fire, orpassive, in which the exposed building is coated or shielded with a noncombustible or fire resistive mate-rial, or a large space separation is provided.

Protection needed for the exposed buildings depends on the size and intensity of the exposure fire, the hori-zontal distance from the fire, and the position of the exposed portion in relation to the fire. The growth ofa building fire will depend on a) the nature and quantity of combustibles in the building construction and occu-pancy, b) the amount of ventilation air, c) external factors such as wind velocity, promptness of detection,proximity of the local fire department, and available water supplies. In the vast majority of cases, it is rea-sonable to assume that there will be sufficient ventilation air to feed the fire.

Table 1 combines construction and occupancy to give various degrees of fire exposure classification, andassumes that conditions are favorable for a free-burning fire.

3.1 Exposing Building

3.1.1 Construction

If the exposing building is fire resistive such that the floor and/or roof deck, the framing and the exposingexterior wall (must be blank) are at least adequate for the expected exposure fire duration (so as to con-tain the exposure fire), no separation is needed for the exposed building.

Exposing walls are categorized as either stable fire resistive, Category A or Category B.

If a wall is fire resistive but tied to unprotected steel framing, for example, it may partially collapse as thesteel fails early in a fire and is not considered stable . Such an assembly should be treated as Category A.

Category A groups exposing materials that have some fire resistance or a high melting temperature thatwill not burn through. Consideration is given to the fact that some breakage or opening of panel joints mayoccur during the fire.

Category B groups exposing materials that may burn through with a significant fire exposure, or may meltat fire temperatures, eventually allowing the exposed wall to feel the full effect of radiation.

Masonry walls may be brick, concrete block or stone. Noncombustible (NC) walls have less fire resistanceand are curtain walls constructed of panels such as protected metal, corrugated iron or cementitious panelson steel frame. Combustible walls may consist of wood or rigid plastic building materials. Wood walls with





13/24

an exterior veneer of stucco, brick, masonry, etc., are considered to be Category B (Table 1) when consid-ered as the exposing building (fire exposure from its interior), but is fire resistive when exposed from the exte-rior. The presence of cementitious shingles over exposed wood walls lessens space separation needed, whilethe presence of asphalt shingles over exposed wood walls increases the space separation needed.

3.1.2 Ventilation

The exposure classifications given in Table 1 are based on well ventilated fires in the exposing buildingswith adequate air supply to support the fire growth. Openings or spaces in the building wall are necessaryto admit combustion air, while openings in the roof (vents, skylights, etc.) will discharge hot gases and allowentry of additional air to aid in the fire development. There is normally enough air within a building to feeda fire in the early stages. Typically openings are present or will develop in the early stages of a fire (windowsor skylights break, heat and smoke vents open, combustible construction burns, steel panels buckle, alumi-num panels melt, etc.). Consequently it is safe to assume there will be adequate ventilation for an exposurefire in the vast majority of cases.

3.1.3 Wind

When the exposed building walls are combustible, it is assumed that wind will carry a spark or ember tothe exposed wall and pilot-ignite the surface.

3.1.4 Effect of Fire Department

The exposure categories (as determined by using Table 1) are based on full flame front at the exposurefire, however, long exposures to combustible materials could still cause ignition. It is assumed that the firedepartment and site conditions are adequate for the fire conditions, and that only a brief delay between ignitionand fire department set up will be experienced.

3.1.5 Length of Wall Creating the Fire Exposure

The relative exposure categories given in Table 1 are determined from the nature of the construction andoccupancy in the exposing building, and the construction in the exposed building. An additional factor, how-ever, is the aspect ratio of the potential flame front or the length/height or height/length ratio of the expos-ing wall. When two buildings are exposed by a rectangular building, the building exposed by the longer wallwill experience the greater fire exposure, provided both walls are the same height and are fully aflame.Table 2 reflects the effect of the relative size of the flame front.

3.2 Exposed Building

3.2.1 When Not Sprinklered

The exposed building will usually be sprinklered. If unsprinklered, but in need of sprinklers, sprinklers shouldbe recommended. When not in need of sprinklers, the separation distances determined from Tables 1 and2 still apply.

3.2.2 Construction

Construction types and categories are described in Sections 1.0 and 2.0.

3.2.3 Protection of Openings Category D Walls. Exposed walls having a combustible exterior surface are about as vulnerable to fireexposure as ordinary doors and windows. Installation of fire doors and fire rated glass windows would servelittle purpose. When the separation distance is adequate for Category D exposed walls, ordinary doors andwindows can be tolerated.

Category C Walls. Where separation distances are adequate for noncombustible construction, self-closingor automatic closing steel doors that are blank or have fire rated or tempered glass vision panels may beconsidered equivalent to the wall in fire resistance.

When outside automatic sprinklers are not provided, fire rated glass is preferred in window openings, however,tempered glass may be tolerated. Ordinary windows can also be tolerated if they abut a corridor ofnoncombustible construction and occupancy.





14/24

Fire Resistive Walls. When space separation is minimal, such that fire resistive exterior wall construction isneeded, window openings usually need to be blocked in with material equivalent in fire resistance to thatof the exposed wall, except as noted in Section 2.1.1.3.

3.2.4 Protection Beyond Ends of Exposing Building

When the exposing building is shorter than the exposed one, protection beyond the ends of the exposingbuilding is needed. Protection for the distance X2 Figure 1 beyond the end of the exposing wall should bethe same protection that is required directly in front of the exposing building ( X1 in Fig. 1). The dis-tances X2, X3 and X4 are based on the angle , measured from a line perpendicular to the adjacentwalls at the corner of the exposing wall. As increases, the level of protection needed is reduced. Noadditional protection is needed when exceeds 45 . For more specific details, see Tables 3 and 4.

Levels of exposed wall passive protection are ranked from best to worst as outlined in Table 3.

Fig. 1. Exposed building walls are longer than exposing walls.





15/24

Table 3. Levels of Passive Protection, P

3 Hour Fire Rated2 Hour Fire Rated1 Hour Fire Rated

Category C*Category D*

* see footnotes to Table 1

For example, Category C is one level down from 1 hour fire rated. The protection of openings should beas outlined in Section 2.0 and 3.2.3 for the respective level of passive wall protection.

Table 4. Protection for Longer Exposed Walls

Location of Exposed Wall with Respect to Exposing Wall Directly across 15 15 < 30 30 < 45

Designation on Fig. 1 x 1 x 2 x 3 x 4Distance Protection is Needed For L 0.25S 0.25S 0.5SLevel of Protection* P P P-1 P-2

S = Separation distance needed per Tables 1 and 2. If the actual separation distance d is greater thanS for the type of exposed wall construction provided, the distance (X1, X2 or X3) that passive or activeprotection is needed for openings should be based on S and not d. If S is less than 40 ft (12.2 m) providea level of protection P, P-1 and P-2, of at least 10 ft (3.0 m), 10 ft (3.0 m) and 20 ft (6.1 m), respectively,beyond the end of the exposing wall.

P = Level of passive protection needed per Tables 1 and 2. For details on protection of openings or alternativesprinkler protection, see Section 2.0 and 3.2.3.

P-1 = One level of passive protection less than needed per Tables 1 and 2 for the separation provided.

P-2 = Two levels of passive protection less than needed per Tables 1 and 2 for the separation provided.

L = Length of the exposing building.

3.2.5 Protection of Side Walls When the separation between buildings is adequate for the type of construction available, no additionalprotection is needed for the exposed wall or adjacent sidewall (exterior wall perpendicular to the exposedwall, see Fig. 2). When separation is inadequate for the exposed construction and passive protection or out-side sprinklers are recommended for the exposed wall, and the exposure is longer than the exposed wall,protection will also be needed for some portion of the side wall of the exposed building. In such cases:

a) Determine (using Tables 1 and 2) the safe separation distance (S) needed for that construction.

b) Multiply that figure by 0.5. The result is the distance out from the face of the exposing building thatprotection is needed for the exposed building side walls.

c) Subtract from this the actual separation distance (d) to arrive at (X), the length of the side wall thatneeds outside sprinkler protection (Fig. 2), or passive protection including the protection of openings, asoutlined in Section 2.0.

Outside sprinklers will protect the front wall, if it is at least 5 ft (1.5 m) away from the exposure. If the actualseparation distance (d) is at least equal to 0.5 S, no side wall protection is needed.

When the exposed building is fire resistive (such as masonry), having adequate separation for the wall, buthaving openings, openings need to be filled in with material of sufficient fire resistance along the front wall(or comparably protected) and possibly for some distance along the side wall. To determine this distance:

a) Using Tables 1 and 2, determine the needed separation distance (S).

b) Multiply that figure by 0.5. The result is the distance out from the face of the exposing building to wherefilling in or other protection of the openings in the exposed side wall is needed.

c) Subtract d from this to determine X (See Fig. 2).





16/24

Fig. 2. Protection for side walls of exposed building.





17/24

The same procedure can be used for determining how far beyond that more fire resistant glass alone isneeded (See Section 3.2.3), by multiplying 0.5 times S needed for combustible exposed walls (point beyondwhich plain glass windows are acceptable).

3.2.6 Protection when Walls at an Angle with Exposing Building

The safe separation distances determined from Table 1 and 2 are for cases in which the exposed and exposingwalls are nearly parallel. In that situation the exposed wall feels the most radiation. When heat radiation fallson a wall whose angle is greater than 15 with the exposing wall, the reduced intensity of radiation maybe taken into account. This may be done by use of the multiplier (M) shown in Table 5.

Table 5. Multipliers for Non-Parallel Exposures (This is the angle between the exposing wall and the exposed wall.) M

0 15 1.0015 30 0.9230 45 0.8445 60 0.7560 75 0.6675 90 0.58

90 0.50

Example 3.2.6.1:

In Figure 3, the distance out from the exposing wall to the point where protection is needed may be deter-mined as follows (assume is between 15 D and 30 D for the west exposed wall and between 60-75 for thesouth exposed wall): Assume the exposure is such that the masonry walls are adequate. But if the exposedwalls were parallel to the exposing wall, the separation distance within which openings (currently temperedglass) need bricking in or fire rated glass and window sprinklers is 30 ft (9.1 m). From Table 5, the multi-plier (M) is 0.92 for the longer west wall and 0.66 for the shorter south wall. It is necessary only to adjustthe separation by using the multiplier, which varies with the angle .

The same procedure may be used to determine how far out from the exposing wall that fire rated glass alone

should be installed by calculating the needed separation from this exposure for Category C exposed walls,where tempered glass would be acceptable. For a given situation, assume that figure is 60 ft (18 m) if thewalls are parallel. Since the west wall is between 15 and 30 of being parallel to the exposure, the multi-plier per Table 5 is 0.92. Similarly the south wall is between 60 and 75 of being parallel to the expo-sure, so the multiplier is 0.66. Multiplying 60 ft (18 m) by 0.92 and 0.66 will yield the distance out from (asmeasured perpendicular to) the exposing wall in which fire rated glass is needed along the west (55 ft, 17 m)and south wall (40 ft, 12 m), respectively.





18/24

West Wall

60 ft 0.92 = 55 ft, 18 m 0.92 = 17 m

South Wall

60 ft 0.66 = 40 ft, 18 m 0.66 = 12 m

3.2.7 Protection for Roof When Lower Than Exposing Building

When the roof of the exposed building is below the top of the exposing building, the exposed roof may receivesufficient radiant heat to be ignited. A burning brand, large enough to cause pilot ignition, may also fall onthe roof. For built-up roof coverings (BUR), placing a minimum of 4 lb/ft 2 (20 kg/m 2 ) of pea gravel on the roofin a flood coat of coal tar or asphalt is recommended. For single-ply membranes, large stone ballast or paverblocks may be used. (See Data Sheet 1-29.) It would only be necessary to provide this protection within50 ft (15 m) of the exposure; however, the remaining portion of the roof should have a Class A rating, forthe distance defined in recommendation 2.8.

3.2.8 Protection of Walls Above Lower Exposing Building

When the height of the exposed building does not exceed the height of the exposing building, use Tables 1and 2 to determine the safe separation distance or needed protection for the entire exposed wall. Whenthe height of the exposed building exceeds the height of the exposing building (Fig. 4a), and the separa-tion between buildings is not adequate according to Tables 1 and 2, protection for the portion of the exposedwall that is above the height of the exposing wall should be provided as outlined in Figures 4b and 4c. Thetype of protection needed should be based on the severity of the exposure (Tables 1 and 2) and the hori-zontal separation distance between buildings.

Fig. 3. Protection for exposed building when walls are at an angle ( ) with exposing building.





19/24

When there is considerable height difference between a significant exposure and the higher exposed building,the level of protection of openings may be decreased one level for each story height above the distanceof needed protection according to Figures 4b or 4c. As in example 3.2.8.1 below, windows on floors onethrough seven need to be bricked in (or have sprinklers and fire rated glass), those on the eight floor shouldhave fire rated glass, those on the ninth floor should be tempered (or fire rated).

Example 3.2.8.1

In Figure 4a, a nine-story sprinklered building with 12 in. (300 mm)-thick brick exterior walls and plain glasswindows is exposed by a three-story unsprinklered building. Separation distance is only 30 ft (9.1 m).

The exposing building is a plank-on-timber fully occupied furniture warehouse having wood walls and a firearea of 15,000 ft 2 (1,400 m 2 ) per floor. The length of the exposing wall is 112 ft (34 m). The story heightin both buildings is 15 ft (4.6 m). What protection is required for the openings in the exposed building?

Solution: The exposing building is multi-story, with wood walls and plank-on-timber floors, so the occupancyshould be treated as high regardless of the exposure. Since the length of the exposing wall is 112 ft (34 m)and the height of the exposure is 45 ft (13.7 m), the aspect ratio of the exposure (for use in Table 2) is 2.5.The fire resistance of the exposed brick wall is in excess of 3 hours (see Data Sheet 1-21); however, sepa-ration would need to be adequate for exposed wall Category D for plain glass windows to be acceptable.

The corresponding multiplier from Table 2 for category 1 and 13 is 0.48 and 4.65, respectively (for exposed3-hour fire-rated walls and exposed Category D walls). The respective recommended separation dis-tances are 27 ft (8.1 m) for 3 hour walls and 215 ft (66 m) for wood walls. The separation distance of 30 ft(9.1 m) provided is adequate for the brick walls, but not the plain glass. According to Figure 4b, the heightabove the exposure needing protection is at least 36 ft (11 m). Consequently, since the story heights are 15 ft(4.6 m), protection comparable to a 3 hr wall rating is needed for the first six floors, three up to the top ofthe exposing wall and three above it. The seventh floor and the eighth floor should have protection compa-rable to a 2 hr (blank wall or fire rated glass plus sprinklers) and 1 hr (fire rated glass) exposed wall,respectively. The ninth floor should have tempered or fire-rated glass to provide protection comparable toCategory C.

3.3 Fire Exposure From Yard Storage

Combustibles stored outdoors may create an exposure hazard to nearby buildings.

There are a number of data sheets that consider this problem and discuss protection for yard storage. Theseinclude 7-10, Wood Processing and Wood Working Facilities ; 7-28N, Explosive Materials ; 7-29, Flammable Liquid Storage in Portable Containers ; 7-85, Metals and Alloys ; 7-88, Storage Tanks for Flammable and Combustible Liquids ; 8-3, Rubber Tire Storage ; 8-7, Baled Fiber Storage ; 8-10, Coal and Charcoal Storage ;8-21, Roll Paper Storage ; 8-22, Storage of Baled Waste Paper ; 8-24, Idle Pallet Storage ; 8-27, Storage of Wood Chips ; 8-28, Pulpwood and Outdoor Log Storage ; 7-52, Oxygen . For outdoor storage that is not cov-ered by any of the above data sheets, use this document to determine the separation and protection.

When using this document, yard storage should be categorized as outlined in Appendix A.

3.4 Yard Housekeeping

Unpaved yards with grass, weeds and bushes are hazardous, especially to buildings with combustible walls.Piles of combustibles, stored either in the yard or on nearby property, add to the hazard. Combustible yardstorage may be vulnerable both to incendiarism and to fire spread from adjoining properties. These hazardsmay be reduced by yard paving, metal fencing, and the maintaining of an aisle space along the fence.





20/24

4.0 REFERENCES

4.1 FM Global

Data Sheet 1-0, Safeguards During Construction, Alteration and Demolition

Data Sheet 1-19, Fire Walls, Subdivisions and Draft Curtains

Data Sheet 1-21, Fire Resistance of Building Assemblies

Data Sheet 1-22, Criteria for Maximum Foreseeable Loss Fire Walls and Space Separation Data Sheet 1-29, Roof Deck Securement and Above-Deck Roof Components

Data Sheet 1-57, Rigid Plastic Building Materials

Data Sheet 2-8N, NFPA 13 Standard for the Installation of Sprinkler Systems 1996 Edition

Data Sheet 3-10, Installation and Maintenance of Private Fire Service Mains and their Appurtenances

Data Sheet 7-28N, Explosive Materials

Data Sheet 7-29, Flammable Liquid Storage in Portable Containers

Data Sheet 7-32, Flammable Liquid Operations

Fig. 4a. Protection for exposed buildings higher than the exposing building.





21/24

Fig. 4b. Protection of walls above the exposure (English units).





22/24

Fig. 4c. Protection of walls above the exposure (SI Units).





23/24

Data Sheet 7-52, Oxygen

Data Sheet 7-85, Metals and Alloys

Data Sheet 7-88, Storage Tanks for Flammable and Combustible Liquids

Data Sheet 8-1, Commodity Classification Data Sheet 8-3, Rubber Tire Storage

Data Sheet 8-7, Baled Fiber Storage

Data Sheet 8-10, Coal and Charcoal Storage

Data Sheet 8-21, Roll Paper Storage

Data Sheet 8-22, Storage of Baled Waste Paper

Data Sheet 8-24, Idle Pallet Storage

Data Sheet 8-27, Storage of Wood Chips

Data Sheet 8-28, Pulpwood and Outdoor Log Storage

Data Sheet 9-17, Protection Against Arson and Other Incendiary Fires The subject is also covered in NFPA No. 80-A, which is a guide (non-mandatory language) and not a standard.This data sheet goes into more detail and gives recommendations, especially regarding yard storage, forthe prevention and reduction of the spread of fire.

There are some differences between this document and NFPA 80-A.

APPENDIX A GLOSSARY OF TERMS

Actual Separation Distance (d): The existing or proposed separation distance between adjacent buildingsor between yard storage and a building.

Class 1: Class 1 includes Approved plastic panels and plastic building panels . Approved Foam Insu-lated wall/ceiling constructions which utilize a polyurethane or polyisocyanurate foam core and steel oraluminum-faced panels are considered Class 1. Approved insulated steel deck roof assemblies are also

considered Class 1.Combustible: Combustible includes painted or unpainted wood, rigid plastic building materials that are notApproved, and Class 2 insulated steel decks.

Concrete Block on Exposed (From the Exterior Side) Steel Frame: When any portion of the steel framingis on the exterior side of concrete block, expansion of the steel frame under heat exposure may open up themortar joints. This tends to weaken the wall as well as permit the passage of heat and flame to the unex-posed side. Some credit, however, can be given to this type of wall to act as a fire barrier under reduced expo-sure. If an exterior grade fire resistant coating (such as an intumescent mastic) is applied to the exteriorside of the exposed steel to provide a comparable rating to that of the wall, that rating may be used to deter-mine the separation. Otherwise, using the separation distances for noncombustible construction will providea very conservative estimate of the needed separation.

Exterior Insulation and Finish System (EIFS). EIFS often use expanded or extruded polystyrene insulation

(EPS). The exterior coating for the EPS is a thin (about1

8 in., 3 mm) layer of proprietary plaster-like mate-rial which may be only 50% cement and 50% polymers. It offers considerably less thermal resistance thanstucco (lath and plaster) which is typically 1 2 in. to 3 4 in. thick (13 to 19 mm).

Fire Rated Glass: Glass such as wired glass, glass block or ceramic glass that has passed a minimum 3 4 hourfire endurance test and hose stream test.

Fire Resistive: For more information including specific hourly fire ratings, refer to Data Sheet 1-21, Fire Resistance of Building Assemblies . This category includes concrete (tilt-up, precast, poured-in-place),concrete block, brick (but not quarter brick which is only about 1 2 in. (13 mm) thick when used as a veneerin EIFS systems), metal sandwich panels with a gypsum board core, and plaster/stucco (not EIFS). Wellmaintained concrete or masonry walls without openings generally need little or no separation or protectionagainst fire exposure.





24/24

High Hazard Occupancy: Storage of Class 3 or 4 or greater hazard commodities, storage of flammable liquids,plastics, roll paper, rubber tires and storage of any material judged to have a comparable or higher hazard.When palletized storage of Class 3 commodities are no more than one tier or 6 ft (1.8 m) high, the hazardmay be reduced to Ordinary.

Light Hazard Occupancy: Manufacture of noncombustible products in which small amounts of cutting oils,flammable liquids, or other combustibles are used. Assume a light hazard occupancy for use in Table 1 whenthe exposing building is a hospital, office (with minimal combustible furniture and limited books and papersin the open), school, or other building having a comparable occupancy hazard, or when any portion of theexposing building is combustible and the building is vacant. This classification can also be used for thepalletized storage of Class 1 or 2 commodities to one tier high or 6 ft (1.8 m).

Noncombustible (NC): Noncombustible walls usually consist of panels over steel framing. Panels may bepainted or galvanized steel, corrugated iron, or corrugated cementitious supported on a steel frame. Thepanels are light in weight, and unless protected or adequately separated, they may buckle and open at their joints, or crack under fire exposure. Since heat will easily conduct through thin steel and ignite combus-tible insulation, insulations acceptable for use in this category include glass fiber, mineral wool and expandedglass. For other types of insulation, see Class 1 or combustible categories.

Noncombustible panels also include protected metal panels and fiber-reinforced cement panels Approved

and listed under Exterior Roofing and Siding. Ordinary Hazard Occupancy: Manufacture of Class 3 and Class 4 commodities. Storage of Class 1 or 2 com-modities, and storages of Class 3 palletized commodities to one tier high or a maximum of 6 ft (1.8 m) high;metal-working in which significant amounts of cutting oils are present; or when the exposing building isoccupied as a hotel, dwelling, retail store, garage, or any occupancy where there is a moderate amount ofcombustible material.

Safe Separation Distance (S): The distance recommended per this document to prevent ignition of a buildingor its contents due to an exposure fire in an adjacent building or yard storage.

Stable Fire Resistive (SFR): SFR walls are constructed of materials having a fire resistance rating at leastadequate for the exposing occupancy. The exposing wall must be constructed so that it will not collapse in anuncontrolled fire. This includes freestanding fire walls. It does not include fire walls that are laterally supportedby structural framework that does not have adequate fire resistance.

APPENDIX B DOCUMENT REVISION HISTORY

In September 1999, the March 1979 version was completely revised.



1-20 Protection Against Liquid Damage

Documents

Transcript of 1-20 Protection Against Liquid Damage