How did GFA harmonisation play out in a real district like One-North?

One-North gives a concrete before-and-after. Bloomsbury Residences, launched in April 2025, was the area's first harmonised project, at an average of $2,474 psf. Earlier launches nearby, Blossoms by the Park, The Hill @ One-North and LyndenWoods, included air-con ledges and bay windows in their strata area despite similar headline psf (EdgeProp; 99.co).

Once that non-liveable space is stripped out, the saving at One-North's psf range works out to roughly $107,000 to $172,000 per unit depending on size. It shows up in yield too: a harmonised 2-bedroom renting for the same as a comparable older-rules unit earns about 3.32% gross versus 2.70%, because the purchase price was not inflated by space you cannot rent out.

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Buyer's Guide · GFA Harmonisation · April 2026

Before June 2023, Singapore developers could charge you for AC ledges, oversized bay windows and empty ceiling voids: space you could never use. One URA rule change closed that loophole for good. This is what changed, which projects are now harmonised, and how much it actually saves you.

1 Jun 2023Harmonisation takes effect
4 to 5%Of unit area was previously AC ledge
~$45KAvg buyer saving on 1,000 sqft unit
Mar 2024First harmonised project: Lentor Mansion
What Is GFA Harmonisation? The Simple Version
Why it matters more than most buyers realise

Before June 2023, when a developer told you a condo unit was 1,000 sq ft, that 1,000 sq ft included spaces you could not actually live in. Air-con ledges, ceiling voids, bay window ledges, and wall thicknesses measured in ways that inflated the number. You paid PSF price for every square foot, including the parts that were pure concrete or open air. GFA harmonisation ended that.

+ Why Four Agencies Once Measured Floor Area Four Different Ways →− Collapse

Gross Floor Area (GFA) is the number that governs how big a building can be on a given plot of land. Before harmonisation, four government agencies, URA, SLA, BCA, and SCDF. Each measured floor area differently. URA's GFA included the full wall thickness. SLA measured only to the middle of the wall. BCA used its own definition. SCDF used yet another. This patchwork created grey zones that developers exploited. Legally, but at the buyer's expense.

In September 2022, URA announced a unified standard effective 1 June 2023: all four agencies would adopt a single, consistent measurement framework. The result: the space you pay for is now the space you can actually use.

The History: How We Got Here
A series of loophole closures, each triggered by developer excess
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2007 to 2008
The bay window era. Developers worked out that bay windows, planter boxes and private enclosed spaces didn't count as GFA but could still be sold as strata area at full psf. A 1,200 sq ft unit might include 120 sq ft of bay windows and planter ledges the buyer paid for and could barely use.
2009
URA closes the first loophole. Bay windows and planter boxes are brought into GFA. Developers move on to other tactics: oversized balconies, private roof terraces and, eventually, AC ledges.
2013
URA closes the second loophole. Private enclosed spaces and private roof terraces are treated as bonus GFA. Developers adapt again, and the AC ledge (up to 1m wide and not counted as GFA) becomes the new way to squeeze out value.
Sep 2022
URA announces the final loophole closure. GFA definitions are harmonised across all four agencies from 1 June 2023, and GLS sites tendered from 1 September 2022 fall under the new rules. AC ledges sold as strata area now count as GFA, which gives developers a financial reason to make them common property instead and stop charging buyers for them.
1 Jun 2023
Harmonisation takes effect. All development applications submitted from this date follow the new unified GFA definition. Strata area = GFA. Voids excluded from strata area. AC ledges excluded from strata area if designated common property.
Mar 2024
Lentor Mansion launches as Singapore's first harmonised condo. The floor plans are immediately different: no strata AC ledges, no oversized bay windows, no void spaces charged to buyers. Every square foot on the floor plan is a square foot you can walk on.
The Three Changes That Actually Matter to Buyers
What harmonisation specifically eliminated from your purchase
Feature ❌ Before Harmonisation ✅ After Harmonisation Buyer Impact
Air-Con Ledges Included in strata area: you paid PSF price for it Designated common property: excluded from your strata area and GFA Saves 4 to 5% of unit area (~40 to 50 sq ft on a 1,000 sq ft unit)
Ceiling Voids / Loft Spaces Included in strata area: a 600 sq ft floor sold as 800 sq ft by adding 200 sq ft of air above Excluded from strata area: you pay only for the floor plate you can walk on Ends "selling air": especially important for loft and penthouse units
Wall Thickness Measurement URA measured to outer wall edge: inflating the number versus what you actually own All agencies now measure to middle of wall: consistent, accurate Reduces strata area by ~1 to 2%: every PSF comparison is now apples-to-apples
Curtain Wall Systems Full-glass curtain walls were "free" area: sold to buyers but not counted as GFA cost for developers Curtain walls now count as GFA: developers bear the cost; most switch to standard window walls Mass-market projects move to conventional windows: ultra-luxury retains curtain walls at true cost
Side-by-Side: What You Actually Get
A 1,000 sq ft unit before and after harmonisation. Same quoted size. Very different value.
❌ Pre-Harmonisation Unit (e.g. 2019 to 2023 launch)
Living / Dining ~420 sqft Bedroom ~220 sqft Bathroom ~45 sqft Kitchen ~80 sqft Balcony ~70 sqft (counts as GFA) Bay Window ~35 sqft YOU PAID FOR THIS AC Ledge ~45 sqft YOU PAID FOR THIS Ceiling Void ~25 sqft: AIR = Space you paid for but cannot use
Quoted: 1,000 sqft
Liveable: ~835 sqft
Wasted: ~165 sqft (AC ledge + bay window + void)
You paid for 1,000 sqft. You got 835 sqft you can use.
✅ Post-Harmonisation Unit (e.g. Lentor Mansion 2024+)
Living / Dining ~455 sqft (larger: no wasted space) Bedroom ~240 sqft (larger: better layout) Bathroom ~50 sqft Kitchen ~90 sqft Balcony ~65 sqft Appropriately sized AC Ledge COMMON PROPERTY ✓ Not charged to buyer No Void No Bay Window
Quoted: ~875 sqft (floor plate)
Liveable: ~875 sqft: what you see is what you get
Wasted: 0 sqft
Every square foot on the floor plan is a square foot you can use.
The comparison trap to avoid: A pre-harmonisation unit at 1,000 sq ft is not the same as a post-harmonisation unit at 1,000 sq ft. The post-harmonisation unit has ~165 sq ft more liveable area. When comparing PSF across old and new launches, always adjust for this difference before concluding which is better value.
How Much Does Harmonisation Actually Save You?
Real numbers on a real Singapore purchase
Buyer Savings Illustration: 1,000 sq ft Unit at $2,200 PSF
~45 sqft Typical AC ledge area (4.5% of unit)
~25 sqft Typical bay window / void area saved
~70 sqft Total non-liveable area you no longer pay for
$2,200 PSF paid for all area including non-liveable
70 × $2,200 Cost of space previously wasted
+ BSD saved Lower price = lower stamp duty
≈ S$154,000
The direct saving on price alone (70 sqft × $2,200 psf), before stamp duty savings and before the benefit of bigger rooms for the same quoted size. At OCR prices of $2,200 psf that's a meaningful saving on every purchase. At CCR prices of $3,500 psf, the same 70 sqft is worth $245,000.
BSD compound saving: A $154,000 reduction in purchase price also reduces your Buyer's Stamp Duty. At the 4% BSD tier (on amounts above $1M), that saves an additional ~$6,160 in stamp duty alone. Every dollar of non-liveable space removed from the price has a stamp duty multiplier.
Which Projects Are Harmonised?
The cut-off is simple: GLS launched for sale from 1 September 2022 onwards, development applications from 1 June 2023

The rule applies to all GLS sites tendered from 1 September 2022 and all private development applications submitted from 1 June 2023. Every new launch from early-to-mid 2024 onwards is harmonised. Existing resale condos are not affected. They retain their original strata definitions.

Project District Launch Year Harmonised?
JadeScapeD202018❌ Pre-harmonisation
Lentor ModernD262022❌ Pre-harmonisation
Hillock GreenD262023❌ Pre-harmonisation
LentoriaD262024 (Mar)✅ Harmonised
Lentor Mansion ★ First harmonised condoD262024 (Mar)✅ Harmonised
Chuan ParkD192024❌ Pre-harmonisation
Emerald of KatongD152024✅ Harmonised
Norwood GrandD252024✅ Harmonised
Nava GroveD212024✅ Harmonised
Parktown ResidenceD222025✅ Harmonised
Lentor Central ResidencesD262025✅ Harmonised
Thomson View ResidencesD202026 (Q3 est.)✅ Harmonised
Upper Thomson Road Parcel AD262027 (est.)✅ Harmonised
Chencharu CloseD272026 (est.)✅ Harmonised
All resale condos launched before Sep 2022All❌ Pre-harmonisation rules apply
Why Chuan Park is pre-harmonisation despite a 2024 launch: The Chuan Park is an en bloc redevelopment, not a GLS site. Its site sale and development application came before the harmonisation cut-off, so it follows the old rules, and AC ledges and voids sit inside its strata area at full psf. See the full breakdown in Chuan Park vs Chuan Grove.
The comparison trap: A 1,100 sq ft pre-harmonisation resale unit can look bigger than a 970 sq ft harmonised new launch. Take out the 130 sq ft of AC ledge, bay windows and void from the resale unit, though, and the living space is about the same, or the new launch may even have bigger rooms. Always compare liveable sq ft, not quoted strata sq ft.
Six Reasons Why Harmonised Projects Are Better for Buyers
Beyond the headline saving: the structural advantages
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1. Every square foot you pay for is a square foot you can use. The quoted size on the floor plan is the actual liveable area. No deductions required. No mental arithmetic about what is unusable.

2. PSF comparisons are finally accurate. Comparing a harmonised launch at $2,400 PSF against a pre-harmonisation resale at $2,000 PSF requires adjustment. The $2,400 PSF buys 100% liveable space. The $2,000 PSF buys ~93% liveable space plus AC ledges and voids. The true PSF gap is narrower than it looks.

3. Room layouts are more efficient. Without oversized AC ledge protrusions and awkward bay window bumps, developers design square, functional rooms. Furniture fits better. Space flows better. Living quality improves for the same quoted size.

4. Lower purchase price means lower BSD. Removing 70+ sq ft of non-liveable space from the quoted strata area reduces the purchase price and therefore the stamp duty payable. The saving compounds.

5. Resale comparison is cleaner. When you eventually sell, your buyer is comparing against other harmonised units. The PSF benchmark is consistent. There is no valuation confusion about whether your unit's strata area includes or excludes AC ledges.

6. Land cost efficiency benefits buyers. Developers bid lower for GLS sites post-harmonisation because they have less saleable area to recover against. Lower land cost is a structural support for launch prices. It does not automatically mean lower prices, but it removes upward pressure on PSF pricing that the previous system created.

James's Note: The Managing Agent's View on What You Actually Live In

In over a decade managing residential estates, the AC ledge complaint came up again and again, especially in condos built between 2010 and 2020. Owners who paid $2,000 psf for a 1,100 sq ft unit were surprised to discover that 50 sq ft of that was concrete ledge outside their window, inaccessible except to the aircon technician...

Read James's full note →

In over a decade managing residential estates, the AC ledge complaint came up again and again, especially in condos built between 2010 and 2020. Owners who paid $2,000 psf for a 1,100 sq ft unit were surprised to discover that 50 sq ft of that was concrete ledge outside their window, inaccessible except to the aircon technician. At $2,000 psf, that is $100,000 they paid for outdoor concrete. The frustration was real. Harmonisation closes that permanently for every new launch from 2024 onwards. But the comparison trap, where buyers pass over a 920 sq ft harmonised unit for a 1,050 sq ft older resale because "it's bigger", still happens. It is almost always a false comparison. When I analyse any unit for a client, I now always calculate the liveable floor plate separately, stripping out any non-walkable area before comparing PSF. That is the number that actually matters for how you experience the home every day.

What to Ask Before You Buy: Harmonised Checklist
Four questions every buyer should ask about floor area
Question to AskWhat a Good Answer Looks Like
Is the AC ledge included in the strata area? For harmonised projects: "No. The AC ledge is common property and isn't included in your strata area or purchase price."
Are there any void spaces included in the strata area? For harmonised projects: "No void spaces are included in the strata area. What you see on the floor plan is the liveable floor plate."
What is the liveable area excluding all non-usable spaces? For harmonised projects, the answer should be the same as the quoted strata area. For pre-harmonisation resales, ask for the internal floor plate minus AC ledge and any bay windows.
Was this project submitted under GFA harmonisation rules? Any project with GLS tender from Sep 2022 onwards or development application from Jun 2023 onwards should say yes. Ask for confirmation if uncertain.

Sources: URA Circular, Harmonisation of Floor Area Definitions, September 2022 | ERA Research and Market Intelligence, GFA Harmonisation analysis, May 2025 | Launches.sg, GFA Harmonisation Policy Overview, January 2026 |, GFA Harmonisation Explained, 2024 | PropertyNet.sg, Understanding GFA Harmonization, October 2024 | OTW Homes, GFA Harmonisation Buyer Guide, 2025 | URA, GFA exemption framework; 99.co, floor area rule change analysis

James Ong  |  CEA Reg No. R008385F  |  PropNex Realty Pte Ltd  |  mychoicehomez.com
This article is for informational and educational purposes only. GFA harmonisation rules apply to development applications submitted to URA on or after 1 June 2023 and to GLS sites tendered from 1 September 2022. Project classification (harmonised vs pre-harmonisation) is based on publicly available information and may be subject to individual project-specific variations. The savings illustration uses indicative figures for illustration purposes only. BSD calculations are per IRAS 2024 schedule. Consult a licensed conveyancer and property agent before any transaction decision.