Guide to Bdasoct03-05

Sep 2005 (rev Jan 07)

Guideline BCA Technology Development Division

Guide to the

Buildable Design Appraisal System

The Guide to the Buildable Design Appraisal System is electronically published by the Technology Development Division of the Building and Construction Authority.

© Building and Construction Authority, September 2005

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, without permission in writing from the publisher.

This Guide is subjected to revision from time to time. Nothing herein shall be construed to exempt the person submitting an application or any plans from otherwise complying with the provisions of the Building Control Act (Cap 29) or any rules and/or guidelines made thereunder or any Act or rules and/or guidelines for the time being in force.

While every effort is made to ensure the accuracy of the information presented in this publication, neither the Authority nor its employees or agents can accept responsibility for any loss or damage incurred in connection with the use of the contents.

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Content Page

Introduction 1

General Guidelines

1. Gross Floor Area 2

2. Constructed Floor Area 4

3. Minimum Buildability Score 4

4. Decimal Points 6

5. Module 6

6. Structures to be Included in Computation 6

7. Basics of Buildable Design Appraisal System (BDAS) 7

8. Worked Examples 8

Part 1 Structural Systems

1. Labour Saving Indices for Different Structural Systems 13

2. Structural Areas Consideration 15

3. Prefabricated Reinforcement Consideration 15

4. Structural Systems 16

5. Measurement 24


Part 2 Wall Systems

1. Labour Saving Indices for Different Wall Systems 35

2. Wall Length Consideration 37

3. Prefabricated Reinforcement Consideration 37

4. Measurement 37


Part 3 Other Buildable Design Features

Points Awarded for Other Buildable Design Features 44

1. Standardisation 46

1.1 Columns 46

1.2 Beams 49

1.3 Door Leaf Openings 54

1.4 Windows 55


Content Page

2. Grids 56

2.1 Repetition of Floor-to-Floor Height 56

2.2 Vertical Repetition of Structural Floor Layout 61

3. Others 64

3.1 Multi-tier Precast Columns 64

3.2 Precast or Pre-assembled/Metal Staircases 65

3.3 Precast Meter Chambers 66

3.4 Precast Refuse Chutes 67

3.5 Precast Service Risers 68

3.6 Non-screed Floor 68

3.7 Columns Sit Directly on Top of Piles 69

3.8 Ground Beams on Top of Pilecaps and/or Integrated into Pilecaps 70

3.7 No column stumps 71

(for projects with planning applications made on or after 1 Jan 2007)

3.8 Precast bay windows 72


3.9 Precast planter boxes 73


A. Single Integrated Components (Bonus Points) 74

A.1 Prefabricated Bathroom/Toilet Units complete with piping/wiring 74

A.2 Precast Household Shelters 75

B. Demerit Points 76

B.1 Non-functional void on slab 76

Sep 2005 (rev Jan 07) 1

Introduction

This Guide serves to advise the industry on the computation of buildability score using the Buildable Design Appraisal System. The guide is revised to the requirement specified in Code of Practice on Buildable Design September 2005, and has incorporated changes affecting projects with planning applications made on or after 1st January 2007. Interpretation on the terms and method of measurement/computation are included to ensure that the buildability scores are computed by the industry in a consistent manner. More examples of buildable design scoring are given to illustrate the computation sequence and methodology.

The buildability score of a design consists of 3 main parts:

Part 1: Structural Systems (maximum 50 points);

Part 2: Wall Systems (maximum 40 points);

Part 3: Other Buildable Design Features (maximum 10 points + bonus points for single integrated components)

Indices for structural systems are indicated in Table 1. Indices for wall systems are indicated in Table 2. Buildability points for other buildable design features are indicated in Table 3.

If you have other queries that are not addressed in this Guide, please contact us at:

Technology Development Division

Building and Construction Authority

5 Maxwell Road, #16-00

Tower Block, MND Complex

Singapore 069110

Tel: 63257720 Fax: 63254800

General Guidelines

� Gross Floor Area

� Constructed Floor Area

� Minimum Buildability Score

� Decimal Points

� Module

� Structures to be Included in Computation

� Basics of Buildable Design Appraisal System

� Worked Examples

Sep 2005 (rev Jan 07) Guide to the Buildable Design Appraisal System 2

General Guidelines

1 Gross Floor Area The gross floor area (GFA) of a project is used to determine whether a project is required to comply with the minimum buildability score requirement or not. Once a project is affected by the buildability legislation (GFA of at least 2000 square metres), then depending on the amount of GFA involved and the category of building work, the corresponding minimum buildability score as set out in the Code of Practice on Buildable Design (COP) will apply.

For new developments, the GFA would be as spelt out in the planning permission issued by URA, including any bonus GFA granted (e.g. for balconies etc). This GFA shall be the final and regularised GFA as verified by URA.

In the case of projects involving additions and alterations (A&A) work, the GFA would be the total GFA of all new floor and/or reconstruction of existing floor. As such, an A&A project could be affected by the legislation even if there is no increase in GFA to the existing building or the increase in total GFA of the existing development is less than 2000 square metres as illustrated by the following examples:-

Example 1

Proposed A&A to an existing industrial development involving change of use and a new extension

In this example, there is a decrease in GFA of 2000 m2 of the existing building due to the change of use of part of the building from warehouse to carpark. At the same time, there is an increase in GFA of 2000 m2 to the existing building from the new side extension. Overall, there is no increase in the total GFA of the A&A project.

However, the above project is subjected to the buildability legislation. This is because the legislation looks at GFA of constructed floors, whether new or reconstructed. The amount of GFA in this case is 2000 m2 (assuming that there is no work done for the portion of the building undergoing a change of use).

PLAN

Existing Building Change of use from

warehouse to carpark (affected GFA = 2000 m

2)

New extension with GFA = 2000 m

2


Example 2

Proposed A&A and addition of a new mezzanine floor and 2 new storeys to an existing 7-storey commercial building

In this example, the net change in GFA of the existing development is 1350 m2 while the total GFA of new and reconstructed floors is 2950 m2. The breakdown of the respective GFA is as shown in the table below.

Net Change in GFA

Total GFA of new and reconstructed floors

Re-layout of 1st storey - 900 m2 0 m2

New mezzanine floor + 300 m2 + 300 m2

Reconstruction of 8th storey no change in GFA + 700 m2

Construction of 2 new floors + 1950 m2 + 1950 m2

Total GFA +1350 m2 + 2950 m2

As in Example 1, by virtue of the definition of GFA in the context of A&A work, the above project is subjected to the buildable design legislation since the total GFA of the new and reconstructed floors is 2950 m2. This is despite the increase in the total GFA of the existing building being only 1350 m2 which is less than 2000 m2.

roof

9th storey

mezzanine

3rd

storey

8th storey

7th storey

6th storey

5th storey

4th storey

1st storey

reconstruction of part of existing floor involving GFA of 700 m2

new mezzanine floor with GFA of 300 m2

re-layout of existing floor with GFA of 900 m2 less

2 new floors with GFA of 1950 m2

2nd

storey


2 Constructed Floor Area Once a project is subjected to the minimum buildability score requirement, all constructed floor areas (including reconstructed floor areas) are to be considered when computing the project buildability score (except minor structures as defined in item 6). The constructed floor area is also used to derive the overall buildability score of a project comprising multiple blocks, by pro-rating the buildabilty scores of each of the blocks with its constructed floor area and summing up the pro-rated scores (please also refer to item 7).

3 Minimum Buildability Score Different minimum buildability scores are given for different categories of development. For a new development, the corresponding minimum buildability score can be found in the COP stipulated under Table B (for projects with planning applications made from 1st September 2005 to 31st December 2006) or Table D (for projects with planning applications made on or after 1st January 2007).

For a mixed development, the minimum buildability score will be pro-rated according to the GFA of each type of development.

For an A&A project with the A&A work being carried out outside the existing building, such A&A work is considered as new work. As such, the corresponding minimum buildability score required to be complied by the A&A project is also set out in the COP under Table B (for projects with planning applications made from 1st September 2005 to 31st December 2006) or Table D (for projects with planning applications made on or after 1st January 2007). Examples of A&A work being carried out outside the existing building are those that are constructed outside the envelope of the existing building, such as

� a new extension to the existing building,

� additional storeys over the existing roof etc.

existing building

Illustration 1: Project with A&A work carried out outside an existing building - Minimum buildability score for New Work shall apply

new extension


For a project with A&A work being carried out within the existing building (envelope), the minimum buildability score is as shown under Table C – Minimum Buildability Score for A&A Work (for projects with planning applications made from 1st September 2005 to 31st December 2006) or Table D (for projects with planning applications made on or after 1st January 2007) in the COP. Examples of such A&A work are

� a new mezzanine floor,

� the slabbing over of an existing void within a building,

� the replacement or reconstruction of existing floor etc.

In the case of a project with A&A work being carried out both within and outside the existing building, the minimum buildability score will be pro-rated according to the GFA of the A&A work outside the existing building (new work – Table B or Table D) and the GFA of the A&A work within the existing building (Table C or Table D).

Illustration 2: Project with A&A work carried out within an existing building - Minimum buildability score for A&A Work shall apply

roof

2nd

storey

9th storey

new mezzanine

3rd

storey

8th storey

7th storey

6th storey

5th storey

4th storey

1st storey

A&A work within existing building

A&A work outside existing building (considered as new work)

Illustration 3: Project with A&A work carried out both within and outside an existing building - Minimum buildability score for A&A Work shall be pro-rated according to the GFA of each type of work

new mezzanine floor


4 Decimal Points All calculations should be rounded off to the nearest 2 decimal places except for the overall buildability score and percentage of coverage for other buildable design features, which should be expressed as an integer.

5 Module The basic module (M) denotes 100mm. For example, 3M denotes 300mm and 0.5M denotes 50mm.

6 Structures to be Included in Computation All major structures, including clubhouse and multi-storey carpark, are to be considered when computing the buildability score. Minor structures such as 22 KV substation, guard post, bin centre and trellis can be excluded from the computation, provided that they are not within or structurally linked to the main building.

Guide to Bdasoct03-05

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