You want to push out the back, add a bedroom, lift the roofline. Whether the authorities treat that as a renovation or a from-scratch rebuild, two different approval routes, two different timelines, two very different bills, is decided before you draw a thing. Get the classification right and the rest of the project has a frame to hang on. Get it wrong and you redesign halfway through, after you've already paid for drawings. This guide walks the whole path: the planning test that sets your route, the money metric that sets your budget, the team you must hire, the certificates that close the job, and the things hiding in the ground that decide more than the design ever will.
The short version
- Your works are either an A&A or a reconstruction. A&A (Additions & Alterations) is the lighter approval route; reconstruction (a new build) is the heavier one. Which side you land on is set by a five-part URA test, not a single number.
- Budget on build-up, not GFA. Contractors quote per square foot of what they physically build (the construction floor area), so that is the number that drives your structural bill. Multiply it by the right cost band for your house type, never a flat "$400 psf."
- Landed homes have no plot ratio. Your massing is governed by a building envelope, a height cap plus setbacks, not a GFA multiplier.
- You must hire licensed professionals. A registered architect, structural and M&E engineers, and a roster of licensed trades. Their statutory signatures are what make your submissions valid.
- Two certificates close the build: TOP, which lets you occupy and releases your final loan tranche, and CSC, the permanent legal completion.
- The biggest surprises are underground. The soil report and the survey set decide your foundation, your basement economics, and what land you may have to surrender, long before finishes matter.
A&A or reconstruction, what the test actually is
URA splits landed building work into two plan-lodgment routes. Additions & Alterations (A&A) go in on one track. New Erection or Reconstruction, together the "rebuild" category, go in on the heavier one. Demolish the whole house and you are a New Erection by definition. Keep part of it but go too far, and you cross from A&A into Reconstruction.
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To stay an A&A, a proposal has to satisfy all five of the following conditions. These come from URA's Development Control Guidelines for Additions and Alterations to Landed Housing:
- Additional GFA must not exceed 50% of the approved GFA. Note what is measured: the floor area you are adding, against what was already approved for the house, not how much of the old structure you keep or demolish.
- External walls removed and replaced must not exceed 50% of the approved external walls. This counts all exterior walls, front, rear and both sides, measured together.
GFA versus build-up, and which one sets your budget
Two floor-area numbers do two different jobs, and homeowners routinely conflate them.
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GFA (Gross Floor Area) is URA's planning number, used to control density and to compute development charges. URA's definition is broad: GFA is all covered floor area of a development, regardless of whether the space is enclosed, accessible or usable, unless a specific exemption applies. A roof is enough to make it GFA; walls are not required. An open-sided covered area is GFA unless an exemption removes it.
Build-up, the construction trade's CFA (Construction Floor Area), is BCA's buildability measure of what you physically build. It is broader than GFA: CFA is GFA plus car-park areas, roof screens, covered sky terraces and balconies, pedestrian linkages, basement diaphragm walls, and low-headroom M&E spaces.
That distinction is the one that touches your wallet, because contractors quote per square foot of build-up:
> Construction cost ≈ build-up area (CFA) × cost psf.
What actually counts as GFA, the exemption traps
This is where homeowners lose plot ratio they did not know they had. URA's GFA Handbook is specific on several points that catch homeowners off guard:
- Open balconies are GFA. In non-landed homes a qualifying balcony is counted as bonus GFA above the Master Plan plot ratio (capped at 7% of residential GFA, per circular dc18-07). The "40% open perimeter / 1.5m minimum width" rule governs bonus-scheme eligibility, not whether the area is GFA. So enclosing a balcony is not a free GFA grab, for a bonus-scheme balcony it converts bonus GFA into regular GFA inside the base plot ratio, which can push you over your approved gross plot ratio. Any enclosure needs an A&A submission and URA approval.
- AC ledges are exempt only when non-strata and ≤2.0m wide (measured perpendicular from the wall); beyond 2.0m, the excess counts. Strata AC ledges are always GFA.
- Bay windows have been GFA since 1 January 2009 (circular dc08-17), they have counted as floor area for over fifteen years.
- Voids are excluded, but slabbing over an internal void adds GFA. This is a classic A&A surprise (URA's 2023 harmonisation cited it explicitly).
- Car porches and garages in non-strata (land-titled) landed housing are excluded from GFA. This exemption is specific to non-strata landed homes.
Source: URA GFA Handbook, Balconies, Ledges, Bay Windows, Introduction, Car Porch & Garages in (Non-Strata) Landed Housing; circulars dc08-17, dc18-07, dc22-09.
The envelope, not the plot ratio
Condo sites get a plot ratio, a GFA-per-land multiplier. Landed homes do not. URA's landed development controls have no Gross Plot Ratio column anywhere; the Prevailing Planning Controls table lists minimum plot size, site coverage, setbacks and boundary clearance. Your massing is governed instead by envelope control, a volumetric building envelope defined by a storey-height cap plus setbacks.
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The caps (URA Circular dc15-02, effective 11 May 2015):
- 2-storey landed area: maximum overall height 12.0m, a "2-storey height control." An attic is permitted as an incidental space within that envelope, not as a counted half-storey.
- 3-storey landed area: maximum overall height 15.5m, a "3-storey height control," with an attic permitted inside the envelope on the same basis.
Source: URA Envelope Control Guidelines for Landed Housing (Bungalows / Semi-Detached / Terrace); Circular dc15-02.
The accurate way to describe your allowance is
Your QP team, and the licensed trades behind them
A landed rebuild runs on Qualified Persons (QPs), licensed professionals who sign the statutory submissions. Their signatures are not a formality; they are what makes your submission legally valid.
- The architect, registered with the Board of Architects (BOA): a recognised 5-year architecture degree plus supervised practical experience. The fastest pathway (5-year degree + about 2 years' practical experience including 12 continuous months in Singapore + the Professional Practice Examination) takes about 7 years; a common alternative (degree + 5 years' experience + exam) totals about 10 years. Reckon on 7–10 years depending on pathway.
- The engineers, registered with the Professional Engineers Board (PEB): a Civil & Structural (C&S) engineer for the structure and a Mechanical & Electrical (M&E) engineer for services. These are two separate disciplines, usually two separate appointments. PEB registration takes an accredited ~4-year degree, at least 4 years' practical experience, the Fundamentals of Engineering and Practice of Professional Engineering examinations, and an interview, about 8 years in total.
Source: BOA Register requirements; PEB PE registration requirements.
Because you engage two engineering disciplines, a fees figure you may hear, that an A&A "costs about S$200k in fees", makes more sense once you break it open: architect (indicatively ~S$100k) plus two engineering disciplines (C&S + M&E) at roughly ~S$50k each. That is one architect and two engineers, not a single flat fee. All three numbers are indicative only; real fees scale with construction cost (the 8–12% rule of thumb above).
TOP, then CSC, and the agency path
Two certificates close out a build, and they are easy to mix up.
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TOP (Temporary Occupation Permit), issued by BCA, certifies that the development has met the necessary requirements and clearances to be suitable for occupation, even though some technical-agency items may still be open. It is the milestone the bank waits for: the final loan tranche releases at TOP. TOP is optional, and you remain obliged to obtain the CSC.
CSC (Certificate of Statutory Completion), also issued by BCA, is the permanent one: granted only once the development has complied with all statutory requirements and obtained all agency clearances. It is mandatory and final.
How they relate: you apply through the same BCA portal on the same form, and BCA grants TOP if some clearances are still pending, then CSC once everything is resolved. They are sequential by design, issued at different stages. CSC is typically processed within about 7 working days of a clean submission; the gap between TOP and CSC depends entirely on how fast the outstanding clearances close, it can be quick or it can stretch, and there is no fixed interval.
Before the first wall, soil, survey, and the underground trap
The numbers that move a landed budget the most are not in the renderings. They are in the ground, and the surveys happen early, in a fixed sequence, pre-construction survey, soil investigation, cable detection, asbestos survey (if applicable), and topographical survey, each tied to a project milestone.
A soil investigation comes first: boreholes, a geotechnical report, and the classic five-strata borehole log that shows what sits at each depth. BCA needs it to design the foundation. It decides whether simple strip or pad footings will do or whether you are piling, and switching to a bored-pile foundation can add roughly S$60–150k (indicative). Nothing else swings the structural bill as hard, and you cannot know it without the test, so order it before you commit a foundation budget.
A topographical survey by an LSB-registered land surveyor maps levels, slopes, existing structures, boundaries and trees, and feeds the setbacks and platform levels. It is compulsory for a rebuild, runs an indicative S$4–5k, and is anchored to a Temporary Bench Mark (TBM), a survey datum peg physically installed on site (you will see it tagged with a code such as "TBM 'B' ZF-01-170") that fixes every subsequent level measurement to one fixed point. While you are doing this site due diligence, check whether the plot sits in a flood-prone or low-lying area, PUB publishes a current list of flood-prone areas, because that feeds your platform levels and your drainage design. On trees: in a Tree Conservation Area, removing a tree with a girth above 1m (measured a metre above the ground) needs NParks' written approval, supported by a certified arborist's assessment, and NParks can require you to plant a replacement tree as a condition. Moving a mature tree is hard regardless, because a tree's root ball extends well beyond its canopy. The survey is usually paired with a
Reading the plans you'll be handed, symbols, levels, and the datum
When you buy the existing plans (more on that below), you will meet a grammar of abbreviations. The common ones:
- ST = Structural Plans · BP = Building Plans · MK = Mukim (the land-survey district) · FFL = Finished Floor Level.
- PL = Platform Level (the finished level of an external platform, such as a car porch) · EL = the level of the second storey and above.
- N/V = Naturally Ventilated (windows) · M/V = Mechanically Ventilated (fan or AC). URA requires habitable rooms to be ventilated, so plans mark which method each room uses.
- Stairs: "UP 3R" means step up, 3 risers. R = riser (the step height), T = tread (the step you stand on).
- BCA plan files from the portal follow a naming convention like `A-[MK##]-[Lot]-ST&MEP-01.pdf` (structural) and `…-BP&MEP-01.pdf` (building), handy when you are sorting a downloaded set.
Stair dimensions. BCA's Approved Document caps the riser at a maximum of 175mm (clause E.3.4.1). The minimum tread is 225mm for a stair within a residential unit, a private internal stair, and 275mm for common residential staircases (E.3.4.2). A 300mm tread is a comfort target many architects design to, but it is not the code minimum. And note that BCA E.2.4 exempts a house built for the owner's own use from these tread and riser dimensional rules entirely.
Sewers, drains, and the invert-level trap
PUB issues three site Services Plans, obtainable via SLA's INLIS portal, and their names matter when you order them: the Sewerage Information Plan (SIP) shows public sewers and pumping mains; the Drainage Interpretation Plan (DIP) shows drainage reserves and land reserved for future drainage; and the Water Service Plan (WSP) shows water mains.
A DIP also helps you read the physical infrastructure on a plot. Four types turn up, and which one sits where decides how your sewer runs and where protection is needed:
- Inspection manhole, a round cover, for sewer or deep-drain access.
- Inspection cover, rectangular and lighter, over a shallower line.
- Surface drain grate, a rectangular grid carrying surface water.
- Deep drain or pit, a deeper circular structure for stormwater.
The depth relationship. PUB's rule is a prohibition plus a clearance: do not lay sewer pipes on top of water mains, and keep a minimum 1m all-round separation, because sewage leaking above a water main could contaminate the supply. Actual relative depths depend on the site.
Invert level. The invert is the inside floor of the sewer pipe (not its crown). The depth you dig to reach it is platform level − invert level, so on a plan showing a platform of 110.018 and an invert of 108.368
Electrical, meter, and gate-widening works
A landed rebuild usually means an electrical upgrade. A modern home runs a three-phase 63A supply, enough for an EV charger (for example, a 32A three-phase unit charging in about four hours) plus a home lift, where an older house may have only a single-phase 40A service. The supply chain from the street runs substation → incoming distribution box → pedestal box → your meter compartment.
The connection and cabling costs are market-driven, not government-set: as an indicative guide, an SP service connection runs around S$9–11k, a meter compartment around S$8–9k, and internal cabling around S$50–70k. For the authoritative connection charge, SP Group publishes its rates in the Transmission Service Rate Schedule (priced by contracted kVA). A lightning protection system is mandatory, designed to SS555:2018, with LPS plans submitted before the Occupation Permit; the copper-strip installation is an indicative ~S$12k, again site-dependent.
Converting overhead cables to underground means digging the public road, and only LTA can authorise that, via a Permit to Work on Public Streets (LTA.PROMPT portal), with pre-consultation required well ahead for deep excavation. The works, and their cost, are borne by the applicant.
Widening the gate or shifting the meter. The maximum gate opening is controlled by URA and BCA and can usually be widened, but if the works touch the road edge you will need LTA approval for the culvert or vehicular crossing over the drain, and PUB for anything affecting the drain itself. Plan the lead time: with drawings and agency approvals counted in, a gate-widening or meter shift can run a few months end to end (indicative, it varies with which agencies are involved).
Asbestos, the pre-1991 gate
If your house was built before 1 January 1991, a renovation or demolition triggers a mandatory asbestos survey before work begins, and this applies equally to HDB, condo and landed. Two precision points: the legal trigger is the build date, not the TOP date (usually close, but the law says "built before 1 January 1991"); and for a renovation the survey covers only the areas being worked on, while a full demolition puts the whole building in scope. Even external-only works on a pre-1991 house warrant checking the affected fabric, asbestos hides in old roof sheets, soft-board partitions and lead flashing.
If asbestos is confirmed, MOM recognises two ways to deal with it: remove the asbestos-containing material, done only by an Approved Asbestos-Removal Contractor (AARC), or manage it in place under an asbestos management programme, sealing or enclosing it so it is not disturbed (for example, building a new false ceiling over an affected one). Keep a copy of the survey report either way; it forms part of your BCA submission. MOM approves AARCs (bizSAFE Level 3 or above, a competent person with two or more years' experience, and the WSQ "Remove Asbestos From Workplace" course). As indicative market ranges, expect roughly S$2,000+ for the survey and a five-figure sum for removal, neither is a government-published cost. One practical aside: the Chinese term for asbestos is 石棉 (shí mián, literally "stone cotton"), useful when briefing Chinese-speaking workers who may not recognise the English word.
Source: MOM FAQ, asbestos surveys (updated 14 March 2024); MOM, managing asbestos-containing materials; WSH (Asbestos) Regulations 2014; MOM Apply to be an AARC.
Road reserves, drainage reserves, and the land you may surrender
Your lot plan may carry a road reserve or a drainage reserve, strips of your land you cannot build on. A drainage reserve shows up as a notation like "3.8m D.R." running across an edge of the lot; you build clear of it. An A&A that doesn't physically touch the reserve is generally fine, but take care when setting out a boundary fence near one, building over or into a drainage reserve is a real risk, so keep the fence clear of the reserve line.
The "no compensation" idea needs splitting in two, because LTA describes two distinct scenarios:
- Owner-initiated: if you redevelop, the land in the road reserve must be surrendered to the State free of encumbrances, no payment, though you may count the surrendered area in your plot-ratio and density calculation. A Road Line Plan (RLP) specifies exactly how much land to surrender; it is a surrender requirement, not merely a line on a map.
- Government-initiated: if the government acquires land to build or widen a road, that is a compulsory acquisition under the Land Acquisition Act, and statutory compensation is assessed and paid.
So the "no compensation" outcome applies only to the owner-redevelops case. LTA may revise safeguarding lines when road plans change, but there is no published process by which a reserve is simply handed back to the owner, do not budget on getting reserved land returned.
Source: LTA Road Line Plan FAQ and Explanatory Notes (Jan 2023); Land Acquisition Act.
Cracks, when a hairline is a problem
A quick diagnostic you can use before paying for a survey: paint or plaster cracks around 1mm are cosmetic; cracks wider than about 4mm warrant a structural surveyor's opinion. Algae or rust staining usually signals water ingress, a leak, rather than a structural fault in itself. These are field rules of thumb, not a code test, but they tell you when to escalate from "repaint" to "engage a professional."
Before you start, the practical checklist
Run these before you fall for a floor plan or sign a build contract:
- Classify the works. Walk URA's five criteria (additional GFA, external walls, structural works, roof/storey, attic) plus the two absolute bars (no extra storey, no change of housing form). This fixes your approval route, A&A or reconstruction, and everything downstream.
- Pull the existing plans from BCA PPS (S$45 search + S$65 per set) to see the approved GFA, external walls and structural baseline you are measuring "50%" against, and the property's A&A history. Anything on the ground that isn't in the approved plans is unauthorised until regularised.
- Size the budget on build-up (CFA) × the right band for your house type and finish, not a flat S$400 psf. Add 8–12% QP fees and a separate interior line on top of the shell.
- Order the soil investigation early. It decides piling versus footings, the single biggest swing in the structural bill. Do not commit a foundation budget before the borehole log.
- Commission the topographical survey (compulsory for a rebuild) with the precomp / encroachment report, identify protected trees with an arborist, and check whether the plot is in a flood-prone area.
- Check the underground constraints: sewer alignment and invert (SIP), drainage and any reserve width (DIP), water main (WSP), and whether an RC trench or a road-reserve surrender applies to your lot.
- Confirm the electrical path: is a three-phase 63A upgrade needed, and does anything require LTA road-opening or overhead-to-underground conversion (applicant-borne)?
- If built before 1 January 1991, budget an asbestos survey and an AARC for removal, before demolition.
- Assemble the QP team, registered architect (BOA) plus C&S and M&E engineers (PEB), and the licensed trades behind them, and remember that TOP releases your final loan tranche while CSC