What's included in Thomson's Addition & Alteration (A&A) works service?

Our A&A service covers: initial feasibility assessment, engagement of Qualified Persons (architect and Professional Engineer), preparation and submission of plans to BCA, URA, and other relevant authorities, site set-up and protection, demolition and structural works, construction of new extensions and alterations, M&E rough-in and finishing, internal finishes and carpentry, final inspections, and handover with documentation.

Does Thomson Renovation Contractor handle BCA/URA submission and approval?

Yes. We handle the entire submission process: we brief the QP (architect/PE), coordinate the preparation of drawings and structural calculations, submit to the relevant authorities (BCA, URA, PUB where applicable), respond to any queries or requests for additional information, and only commence works once approval is obtained. We keep you updated at every stage.

What types of structural changes are covered under A&A works?

A&A covers: rear and side extensions (up to 50% increase in GFA), internal wall removal and reconfiguration, mezzanine floor additions within existing volume, attic conversions within existing roof profiles, staircase relocation, new door/window openings in external walls, facade upgrades, and roof alterations. Works that exceed A&A limits — such as full reconstruction or adding a new storey — fall under different planning categories and would require a separate discussion.

How long does an A&A works project typically take, from approval to completion?

The submission and approval phase typically takes 8 to 16 weeks, depending on the complexity and which authorities are involved. Once approved, site works generally run from 3 months (for a straightforward internal reconfiguration) to 12 months or more (for a large rear extension with full internal renovation). We provide a project-specific timeline after the scope is confirmed and the QP has assessed the structural requirements.

How much do Addition & Alteration (A&A) works cost?

A&A costs vary widely based on scope, structural complexity, and material specifications. A simple internal reconfiguration (removing walls, reconfiguring rooms) might range from S$30,000 to S$80,000. A rear extension with full finishes can range from S$150,000 to S$400,000 or more. QP fees, authority submission charges, and any required soil investigations are additional. We provide a detailed cost estimate after the initial survey and feasibility assessment.

Addition & Alteration Singapore | Thomson Renovation Contractor

Addition and Alteration works — or A&A, as it’s known in the trade — covers everything from a rear extension on a landed house to reconfiguring the internal layout of a commercial unit. It is one of the more complex types of renovation because it involves regulatory submissions, structural calculations, and coordination with multiple authorities. At Thomson Renovation Contractor, we have been handling A&A projects for over 10 years, both for residential and commercial properties. We manage the whole process: engaging the right Qualified Persons, preparing submissions to BCA and URA, and executing the works on site. You get one point of contact from approval through to completion.

Planning and Submission

Every A&A project starts with understanding what is allowed. We assess the existing condition of your property, review the relevant planning and building regulations (URA guidelines, BCA building regulations, and fire safety and drainage requirements where applicable), and advise on what can and cannot be done. If the proposed works fall under A&A criteria — less than 50% increase in gross floor area, less than 50% replacement of external walls, and no change to the roof profile or addition of a new storey — we proceed with the submission. We engage a Qualified Person (architect or Professional Engineer) to prepare the necessary drawings and structural calculations, and we submit these to the relevant authorities. We track the application, respond to any queries, and only begin site works once approval is granted.

A&A Works We Undertake

A&A covers a broad spectrum of project types. Below are the main categories we handle.

Our A&A Works Process

Feasibility Assessment

We assess what is achievable under A&A criteria.

QP Engagement & Drawings

We engage a Qualified Person to prepare drawings and calculations.

Authority Submission

We submit to BCA, URA, and other authorities for approval.

Construction

Structural and finishing works once approval is granted.

Final Handover

Walkthrough, snag resolution, and as-built documentation.

New ceiling and plastering works in progress during an Addition & Alteration project

Structural Additions and Extensions

Internal wall framing and partition works during an alteration project

Internal Alterations and Reconfiguration

Contractors carrying out structural opening and reinforcement works on site

External Facade and Roof Alterations

This includes rear extensions to increase ground-floor living space, side extensions where the setback allows, addition of a mezzanine floor within an existing double-volume space, and construction of an attic level within an existing roof profile. All structural work is designed and certified by a Professional Engineer. We use reinforced concrete, structural steel, or a combination — whichever is most appropriate for the existing building and site conditions. We handle the piling (if required), foundation, structural frame, walls, roofing, waterproofing, and internal finishes as a complete package.

Not all A&A involves building outward. Many projects are about reconfiguring what is already there: removing internal walls to create open-plan layouts, relocating staircases, converting an existing room into a larger ensuite bathroom, or turning a ground-floor utility area into a home office or granny flat. We assess which walls are structural and which are not, plan the new layout, and manage the demolition, structural reinforcement (if needed), and finishing works. For commercial unit reconfiguration, we also ensure compliance with fire safety, accessibility, and ventilation requirements.

External works can dramatically improve the look and performance of a building. We handle: replacement or upgrading of external wall finishes (rendering, cladding, painting), installation of new window and door openings (with lintels and weatherproofing), roof repair and replacement, installation of skylights and roof windows, and construction of canopies, awnings, and covered walkways. External facade works often require additional submissions — we ensure all applications to URA and BCA are complete and approved before scaffolding goes up.

Working with Qualified Persons (QP) and Authorities

A&A works in Singapore legally require involvement of Qualified Persons (architects and/or Professional Engineers) for structural elements, and submissions to BCA, URA, and sometimes PUB, LTA, or NParks — depending on the property and the scope. We have built a reliable network of QPs we work with regularly. We engage them on your behalf, brief them on the project scope, and coordinate the drawing and submission process. You do not need to find your own architect or engineer separately. Once submissions are approved, we keep a copy of all approved drawings on site and ensure every stage of construction matches what was submitted. This keeps you protected — both legally and in terms of build quality.

Project Management from Approval to Completion

A&A projects can run anywhere from 3 months to over a year, depending on scope. We manage the entire timeline: from pre-submission planning through authority approvals, site set-up and protection, structural and wet works, M&E (mechanical and electrical) rough-in, internal finishes, carpentry, and final inspections. You receive regular progress updates with photos, and we flag any issues early — cost variations due to unforeseen site conditions, for example, are discussed before any new work proceeds. At completion, we walk through the finished project with you, address any snags, and provide all relevant warranties and as-built documentation.

Frequently Asked Questions

Question	Answer
What's included in Thomson's Addition & Alteration (A&A) works service?	Our A&A service covers: initial feasibility assessment, engagement of Qualified Persons (architect and Professional Engineer), preparation and submission of plans to BCA, URA, and other relevant authorities, site set-up and protection, demolition and structural works, construction of new extensions and alterations, M&E rough-in and finishing, internal finishes and carpentry, final inspections, and handover with documentation.
Does Thomson Renovation Contractor handle BCA/URA submission and approval?	Yes. We handle the entire submission process: we brief the QP (architect/PE), coordinate the preparation of drawings and structural calculations, submit to the relevant authorities (BCA, URA, PUB where applicable), respond to any queries or requests for additional information, and only commence works once approval is obtained. We keep you updated at every stage.
What types of structural changes are covered under A&A works?	A&A covers: rear and side extensions (up to 50% increase in GFA), internal wall removal and reconfiguration, mezzanine floor additions within existing volume, attic conversions within existing roof profiles, staircase relocation, new door/window openings in external walls, facade upgrades, and roof alterations. Works that exceed A&A limits — such as full reconstruction or adding a new storey — fall under different planning categories and would require a separate discussion.
How long does an A&A works project typically take, from approval to completion?	The submission and approval phase typically takes 8 to 16 weeks, depending on the complexity and which authorities are involved. Once approved, site works generally run from 3 months (for a straightforward internal reconfiguration) to 12 months or more (for a large rear extension with full internal renovation). We provide a project-specific timeline after the scope is confirmed and the QP has assessed the structural requirements.
How much do Addition & Alteration (A&A) works cost?	A&A costs vary widely based on scope, structural complexity, and material specifications. A simple internal reconfiguration (removing walls, reconfiguring rooms) might range from S$30,000 to S$80,000. A rear extension with full finishes can range from S$150,000 to S$400,000 or more. QP fees, authority submission charges, and any required soil investigations are additional. We provide a detailed cost estimate after the initial survey and feasibility assessment.

ADDITION & ALTERATION (A&A) WORKS

Licensed Addition & Alteration (A&A) works in Singapore

ADDITION & ALTERATION (A&A) WORKS