New Approaches to Minimizing Water Intrusion in Attics

Coastal Contractor SummitMay 12-14, 2008

Tim ReinholdDirector of Engineering & VP

Institute for Business & Home Safety

IBHS Mission

To reduce the social and economic effects of natural disasters and other

property losses by conducting research and advocating improved

construction, maintenance and preparation practices.

Performance of New Performance of New Building Code BuildingsBuilding Code Buildings

33

Strong Codes Reduce Claim Strong Codes Reduce Claim Severity and FrequencySeverity and Frequency

(Preliminary Results)(Preliminary Results)

Severity

Pre 1996: $24/sf

1996 - 2004:

$14/sf

- 42%

Frequency

Pre 1996: 41 claims/100 policies

1996 - 2004:

17 claims/100 policies

- 60%

44

Amount of Roof DamageAmount of Roof Damage

4%

20%

51%

25%

14%

48%

33%

5%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

% of

Total Claims

Pre 1996 1996 - 2004

Building Code Category

No Roof Damage Partial Covering Whole Covering Whole Covering with Decking

* Includes claims with known damage types only, except for partial covering/partial decking.

55

Interior Damage and ALE by Interior Damage and ALE by Year of ConstructionYear of Construction

29%

51%

9%

11%

44%

47%

9%0%

0%10%20%30%40%50%60%70%80%90%

100%

% Total Claims

Pre 1996 1996 - 2004

Building Code Category

Interior Damage,ALE ≥ 1 Month

Interior Damage,ALE < 1 Month

Interior Damage,No ALE

No Interior Damage

66

Causes of Failure Causes of Failure and Problemsand Problems

Building Envelope Issues

Structural Issues

Building Envelope Issues in Priority Order

Loss of roof coveringLoss of roof covering Loss of roof sheathingLoss of roof sheathing Debris impact - broken windows and doorsDebris impact - broken windows and doors Window and door framing and anchorageWindow and door framing and anchorage Garage doorsGarage doors Ridge vents, off ridge vents, gable end vents Ridge vents, off ridge vents, gable end vents

and soffitsand soffits Water leakage – windows, doors, siding, etc.Water leakage – windows, doors, siding, etc.

Roof Covering FailuresRoof Covering Failures

95% of HomesWith claims

Roof Coverings - Shingles

3-Tab Shingle Permit Survey Post Charley Replacement

Shingle Roof Observations

Many Older Roofs suffered extensive shingle damage

Roof covering damage frequently resulted in significant damage to interior

Newer wind-rated shingles installed to manufacturers recommendations performed well

How much is due to being new and how much due to product improvements?

Roof Covering Failures

Tile Roof Damage Tile insufficiently

attached to roof deck:

Roof Covering Failures

Roof Covering Failures

Tile Roof Damage Lack of Hip / Ridge

Board

Roof Coverings - Tile

Signs of damage propagation

Success stories were there in Charley

Tile Roof Permit Study (10,375) County & City Population

County & City Tile Roof Permits Post Charley Replacement

Tile Roof Observations Tile roofs have better secondary water

protection When roofs failed, few tile roof owners had as

much water intrusion through deck as shingle roof owners

Some roof vent problems where vents failed and acted as scoops

Relatively light damage in lower winds

Tile failures produced large financial losses Large deductibles

Source of significant debris damage

Florida 2004:A Tale of Two Coasts

On East Coast after Frances and Jeanne, Palm Beach Post Very critical of shingle roofs

Very supportive of tile roofs

In Punta Gorda and Charlotte County Many homeowners concerned about tiles

Numerous positive comments about the performance of new metal roofs

Local covenants requiring tile roofs

Tile Look Metal Roofs

Standing Seam Metal

MetalMetal Anchorage near edges is key Sheathing or deck is important Provide secondary water protection –

upgraded underlayment

Metal Roof Observations Certain new installations performed very

well 5V Crimp seemed among best

Easy to inspect screw spacing Installed over decking

Standing seam exhibited mixed results Sometimes no deck under panels More difficult to inspect clip spacing on deck

applications Systems that include a separate deck offer

opportunity for secondary water protection

Degradation with ageing and fatigue?

Secondary Water Protection

Goal is to dramatically reduce the amount of water that pours into the attic through gaps between roof sheathing when the primary roof cover is blown off.

Underlayment as Secondary Underlayment as Secondary Water ProtectionWater Protection

Fully adhered membrane coveringFully adhered membrane covering

Underlayment as secondary Underlayment as secondary Water ProtectionWater Protection

Mechanically attached membrane

Table 3-4 Horizontal Overlap of "High Performance" Underlayment Sheets to Avoid Sealing Edges

ASCE 7 Fortified Roof Pitch XX on 12

Design Design 5:12 6:12 7:12 8:12 10:12 12:12 14:12 16:12 18:12

Wind Speed

Wind Speed

Required Overlap for "High Performance" Underlayment to Avoid Sealing Edges

mph mph inches inches inches inches inches inches inches inches inches

90 110 15 13 12 11 9 8 8 7 7

100 120 18 16 14 13 11 10 9 9 9

110 130 NA 19 17 15 13 12 11 10 10

120 140 NA NA 19 17 15 14 13 12 12

130 150 NA NA NA NA 17 16 15 14 13

140 160 NA NA NA NA NA 18 17 16 15

150 170 NA NA NA NA NA NA 19 18 17

NA = Not Allowed - overlap is greater than 19-inches.

Secondary Water Protection Secondary Water Protection Using Self Adhering StripsUsing Self Adhering Strips

• Self Adhering Modified Bitumen products• Ice & Water

shield• Available in a

Variety of Widths• Most Economical

in 6” widths

Closed Cell Urethane Based Adhesive Foam

Sprayed on Joints

Medusa

Tearing Around Fasteners

Roof Deck Failure

Roof Deck and Gable End Roof Deck and Gable End FailuresFailures

Loss of Roof Sheathing & Gable Loss of Roof Sheathing & Gable End FailureEnd Failure

Key Elements for Roof Key Elements for Roof Sheathing AttachmentSheathing Attachment

fastener size and typefastener size and type fastener spacing – particularly in the field of fastener spacing – particularly in the field of

sheathingsheathing(These two items have the greatest effect on uplift resistance)(These two items have the greatest effect on uplift resistance)

Spacing of support membersSpacing of support members Sheathing thickness (head pull-through); Sheathing thickness (head pull-through);

fatigue around fastenersfatigue around fasteners

Sheathing Uplift ResistanceSheathing Uplift Resistance Uplift capacity is best correlated with tributary Uplift capacity is best correlated with tributary

areas of fastenersareas of fasteners Depends on missing fastenersDepends on missing fasteners Depends on head pull-through for thin Depends on head pull-through for thin

sheathing ( < 5/8”)sheathing ( < 5/8”) For 1/2” or thinner sheathing - can be reduced For 1/2” or thinner sheathing - can be reduced

based on nail head shapebased on nail head shape For 1/2” or thinner sheathing - can be reduced by For 1/2” or thinner sheathing - can be reduced by

over-driven fastenersover-driven fasteners

For screws, capacity can be limited by head For screws, capacity can be limited by head pull-through even for 5/8” sheathingpull-through even for 5/8” sheathing

2 sq. ft.2 sq. ft.

1 ft.1 ft.

2 ft.2 ft.

1 ft.1 ft.

½ ft.½ ft.½ sq. ft.½ sq. ft.

Ratio of Tributary Areas = 4 to 1Ratio of Tributary Areas = 4 to 1

6 and 12 spacing of fasteners6 and 12 spacing of fasteners

4141

1 sq. ft.1 sq. ft. 1/2 ft.1/2 ft.

2 ft.2 ft.

1 ft.1 ft.

½ ft.½ ft.½ sq. ft.½ sq. ft.

Ratio of Tributary Areas = 2 to 1Ratio of Tributary Areas = 2 to 1

6 and 6 spacing of fasteners6 and 6 spacing of fasteners

4242

Roof Ventilation as a Source of Water Intrusion

Soffits Gable rake vents Gable end vents Ridge vents Off-ridge vents TAS 100(A) type tests are all that are

currently available to try and evaluate some of these products

Soffit FailuresSoffit Failures

75% of Homes with claims

Failure Due to Failure Due to

Poor Installation – Lack of Test Poor Installation – Lack of Test Standards – Not Following Product Standards – Not Following Product ApprovalsApprovals

Major Code Change

Soffits to be designed to withstand the same pressure as the adjacent wall

Dead-wood and following manufacturer’s installation procedures is important

Retrofit solutions indicate issues

Retrofitting Vinyl and Aluminum Soffits

Anchorage of soffit to wall Bead of adhesive Screws through channel and soffit material

Anchorage of soffit to fascia board Adhesive in notches Screws through fascia flashing and soffit material

Improved anchorage of flashing Removal and installation per manufacturer’s

high-wind installation recommendations

Ridge Vents

Gable End Vents

Gable End Rake Vents

Gable End Rake Vents

Off Ridge Vents

Nails holding off-ridge vent in place

Off Ridge Vent Failure

The Bad News about Code Provisions

Roof coverings are still a major problem area (95+% of homes with claims had roof covering damage)

No good test procedure for soffits and water intrusion through soffits (75% of homes with claims had soffit damage)

The Really Bad News Many coastal areas are not using modern

engineering based standards for housing construction

The migration of people to the coasts is expected to continue

Values of coastal properties are continuing to escalate

We are in a cycle of increasing frequency of events

Demand Surge- cost of material spike Climate change – NOAA 90%+ confidence =

higher wind speeds in hurricanes

What About Sealed Attics?

Improved energy efficiency Get rid of attic vents all together Depending on type of insulation – can

provide additional protection from water intrusion

Use of Air Admittance Valves – could just about eliminate roof penetrations.

Air Admittance Valves www.durgo.com www.oatey.com www.rectorseal.com www.studor.net

Why not think about…

Code Plus Construction Options

Beyond Building Codes Increases design loads for pertinent hazards Performance based criteria with some

prescriptive options Paying attention to water penetration Wind and/or hail impact resistant roofing Formal design review Connections, connections, connections Verification through targeted inspections Some limited insurance discounts are

available

IBHS Research Center