Addition and alteration (A&A) projects involve modifying, extending or upgrading an existing building rather than starting entirely from a cleared site. In Singapore, the precise regulatory requirements depend on the property and scope of works; for example, alterations that increase gross floor area generally require planning permission or an applicable lodgement process.

Understanding the main construction stages helps property owners see how design, approvals and physical works connect. Builders in Singapore typically work alongside architects, engineers and other specialists to translate approved plans into completed building works.

What Happens Before an A&A Construction Project Begins?

Before physical construction starts, the existing property and proposed scope need to be established. For landed housing, URA defines criteria distinguishing qualifying A&A proposals from reconstruction, including limits relating to additional gross floor area, replacement of external walls and structural changes.

Early-stage work may include:

• reviewing the condition and configuration of the existing building;
• identifying which areas will be retained, altered or demolished;
• defining the intended additions and alterations;
• checking applicable planning and building requirements; and
• appointing relevant professionals for design and submissions.

For qualifying landed-house lodgement applications, a Qualified Person, such as a registered architect or engineer, must be appointed.

This stage establishes the project’s constraints and scope before detailed design proceeds.

What Happens During the Design and Planning Stage?

The design stage converts the project requirements into coordinated drawings and technical information. Architectural plans establish spaces and building form, while structural plans address elements such as beams, columns and floor structures.

Mechanical and electrical (M&E) requirements also need to be coordinated with these plans. This can include electrical, plumbing, air-conditioning and other building services affected by the alterations.

Regulatory submissions depend on the works involved. BCA states that building works generally require a permit unless they fall within the category of insignificant building works, while structural plans must be approved where applicable before structural works proceed.

An A&A contractor in Singapore can therefore work from coordinated and approved information when construction begins.

What Happens During Site Preparation and Demolition?

Once the relevant requirements for starting work have been satisfied, the site is prepared for construction. Existing elements identified for removal can then be demolished while retained parts of the building are protected.

Typical activities include:

• establishing work and storage areas;
• protecting retained finishes or structures;
• disconnecting or protecting affected services;
• removing specified walls, finishes or structural components; and
• clearing demolition debris.

Demolition may expose conditions that could not be fully observed beforehand. Where a material change to an approved structural design becomes necessary, BCA requires approval before that structural change is carried out.

The resulting site provides the basis for structural and building works.

What Happens During Structural and Building Works?

Structural work creates or modifies the main load-bearing elements required by the design. Depending on the project, this may involve foundations, columns, beams, slabs, walls, roofs or extensions.

BCA requires structural plan approval and a permit before applicable structural works begin. The permit application is made jointly by the developer, Qualified Person and builder carrying out the work.

The work must also account for the interface between existing and new construction. This makes coordination between engineers and builders important throughout this stage.

Once the main building elements are in place, M&E installation and subsequent finishes can progress according to the construction sequence.

When Are M&E Systems Installed During an A&A Project?

M&E installation is normally coordinated with structural and architectural works rather than treated as an entirely separate stage. Service routes need to correspond with walls, ceilings, structural elements and equipment locations.

Work may cover:

• electrical wiring and distribution;
• water supply and sanitary plumbing;
• air-conditioning and ventilation services; and
• associated equipment and controls.

Concealed services are generally installed before the relevant walls and ceilings are closed. Coordination helps prevent service routes from conflicting with structural or architectural elements.

After these installations and the associated finishes are completed, the project can move towards testing and completion.

What Happens During Testing, Inspections and Project Completion?

The final stage checks whether completed works and relevant systems meet project and regulatory requirements. Required inspections and completion procedures vary according to the type and extent of building work.

Testing and completion activities may include checking installed building services, rectifying identified defects and preparing required completion documentation. Where applicable, the relevant professionals also handle procedures associated with a Temporary Occupation Permit (TOP) or Certificate of Statutory Completion (CSC).

For conserved buildings, for example, URA states that TOP/CSC clearance is granted only when works are completed according to approved plans.

The responsibilities of the Qualified Persons, consultants and A&A contractor therefore continue through inspection, rectification and formal completion rather than ending when physical construction finishes.

Reach out to Colebuild to know more about how planning, structural works, M&E installation and inspections fit together to help property owners prepare for each stage of an A&A project.