By Gary Lim · Senior Division Director, ERA Realty Network · CEA Reg. No. R009877B · Published 22 September 2026 · Computed from 240,919 HDB resale records, plus four archive datasets back to January 1990

Twenty-one models, and ten of them are invisible

Everybody has an opinion about rare HDB flat types. Almost nobody has a count. So I went and got one.

HDB records a flat_model against every resale transaction it publishes. I pulled the count for every distinct model across all 240,919 transactions in the current registry, from January 2017 to September 2026. There are 21 models, and their counts sum to exactly 240,919 with a residual of zero.

That reconciliation matters more than it sounds. It proves three things at once: the model list is complete, every individual count is right, and the total is right. You cannot get a residual of zero by accident.

Then I went back through the four archive datasets to January 1990 — another 746,203 transactions — to see how far back each model goes. And for two of the rare models I derived, from HDB’s own block register, exactly how many units of them exist, which is a different and much harder question than how many have sold.

Here is what nobody writes down: the ten rarest models in Singapore account for 1,908 transactions out of 240,919 — 0.79% of the entire resale market. Four in every five hundred. And one of them just set a price this month that put it second on the all-time national list.

The rare models at a glance

The complete flat model inventory

All 21 models, ranked. This is the table I could not find anywhere else, so I built it.

Four models — Model A, Improved, New Generation and Premium Apartment — are 83.5% of the entire Singapore HDB resale market. Everything else is a rounding error, and the bottom ten are a rounding error on the rounding error.

And the depth behind that table: across the five HDB resale datasets published on data.gov.sg, coverage runs continuously from January 1990 to today — 287,196 records for the 1990s, 369,651 for 2000 to February 2012, 52,203 for March 2012 to 2014, 37,153 for 2015–2016, and 240,919 from 2017. 987,122 transactions in total. Nothing before January 1990 is published anywhere machine-readable.

What counts as one of the rare HDB flat types

I drew the line at 500 transactions since 2017, which puts ten models below it. That is not arbitrary — there is a natural gap in the data. Model A2 sits at 2,703 and the next model down, 2-room, sits at 507. Below that everything falls away fast.

Two of those ten I have already written about at length: executive maisonettes and jumbo flats. HDB terrace houses, the rarest housing in the country at 285 units, I covered separately. So this article concentrates on the five that nobody writes about properly: Multi Generation, Type S1, Type S2, Premium Apartment Loft and 3Gen.

One footnote before we start, because it surprised me. The two rarest models in the entire registry are Premium Maisonette (22 sales) and Improved-Maisonette (32 sales) — rarer than anything the property press ever covers, rarer than terrace houses, rarer than Multi-Generation flats. They are maisonette variants, so they belong with the maisonette piece rather than here, but if you own one, you own something genuinely scarce.

Multi-Generation: 367 units, and I counted them myself

In 1987 HDB built a flat designed for three generations under one roof: a four- or five-room flat with an adjoining studio apartment that had its own separate entrance. Parents in the studio, children in the flat, one front door each.

It built them in 1987 and 1988. Then it stopped, and never built another.

The count nobody publishes — derived, not repeated

HDB’s block register carries a field called multigen_sold: the number of Multi-Generation units in each block. Sorted descending, exactly eight blocks have a value above zero — the ninth and tenth rows are zeroes, which proves the list is complete rather than truncated.

By town: Yishun 174, Tampines 100, Bishan 93. And the eight blocks in the register are exactly the eight blocks that appear in nine and a half years of resale transactions — two completely independent datasets agreeing without being made to.

Then, after I had the number, I found that DollarsAndSense published 367 back in September 2020. I had no idea until afterwards. Deriving a figure independently and landing on someone else’s published one is about the best validation available, and I would rather tell you that than pretend I found something new.

The record, and a claim that has gone badly stale

The record works out to about $782 psf — which is remarkably cheap per foot for a million-dollar-plus flat, and tells you exactly what you are buying. You are buying floor area, not price per foot.

Note also what has happened to a widely-cited figure. In October 2022, 99.co reported a $1,063,000 sale as “the first-ever million-dollar multi-generation HDB resale flat”. That headline still circulates. The record is now 30.7% higher.

If 165 sqm for $1.39m sounds like a lot of flat for the money, that is because it is. It is also a 39-year-old lease, in three towns only, with a buyer pool measured in dozens. Run the numbers before you romanticise it — the affordability and stamp-duty calculators at listings.sg/tools will do that part in a minute.

Type S1 and Type S2: the Pinnacle models

Two of the 21 models in HDB’s registry exist at a single address. Type S1 and Type S2 are the Pinnacle@Duxton, and nothing else.

I checked this rather than assuming it: all 389 Type S1 transactions are in the Central Area, and all 389 are on Cantonment Road. Same for all 198 Type S2 sales. Every single Type S1 or S2 flat ever sold in Singapore is in those seven towers.

The unit counts come out of the block register cleanly. Blocks 1A through 1G, seven towers, each 50 storeys, each with 264 dwelling units split 176 four-room and 88 five-room. Seven times 176 is 1,232. Seven times 88 is 616. Total 1,848, which is the Pinnacle’s published unit count. Block 1 itself is recorded as non-residential with zero dwelling units — the commercial podium.

What is striking about the Pinnacle models is how normal the psf is relative to their reputation. Median around $990 psf for both, with records around $1,477 to $1,500. Those are Central Area numbers, not fantasy numbers. The scarcity is in the address and the sky bridges, not in a price nobody else can reach — and for context on how the very top of the HDB market is actually built, see my running count of million-dollar HDB flats.

Premium Apartment Loft: two towns, 139 sales

The Premium Apartment Loft is a double-height, mezzanine-level HDB flat. It exists in exactly two places.

The record — $1,700,000 at Blk 92 Dawson Road in February 2026, 122 sqm on the 19th to 21st floor, about $1,295 psf — makes the Dawson lofts one of the most expensive HDB products in the country.

And here is the detail I like best about them. In June 2026, a loft at Blk 93 Dawson Road on the fourth to sixth floor sold for $1,650,000. Same size, same model, adjacent block, four months later, fifteen floors lower — and only $50,000 behind. That June sale is the seventh-highest HDB price ever recorded, and it is on the fourth floor. For a rare model, layout is doing far more work than height.

How many exist? I don’t know, and I am not going to estimate. HDB’s block register has no loft field — lofts are folded into the ordinary four-room and five-room counts. So unlike Multi-Generation and the Pinnacle models, this one cannot be derived from public data. Anyone who quotes you a number for how many lofts exist is guessing.

3Gen: 84 sales, and a resale trap

The 3Gen flat is HDB’s modern answer to the same question the 1987 Multi-Generation flat asked: how do you house three generations? It was introduced in 2013, and it is a genuinely different product from its 1987 ancestor — which, as we will see, is a distinction three major publishers have failed to make.

The record is $1,278,888 at Blk 228A Ang Mo Kio St 23 in July 2026, from the 25th to 27th floor, about $990 psf. Treat that one carefully: it is $240,000 clear of the next-highest 3Gen sale ever, on a single transaction. That is an outlier, not a trend, and I would not price anyone’s flat off it.

The 115 sqm question

You will see 3Gen flats described as “about 115 sqm”. Every one of the 84 resales in the registry is recorded at 119 to 123 sqm.

I was ready to call that a competitor error. It isn’t. 115 sqm is the Government’s own published figure, on factually.gov.sg. The registry consistently records a larger measured area. The honest reading is that the two are measuring on different bases — HDB quoting an internal floor area, the registry recording a larger measured one — not that anybody is wrong. If you are comparing a 3Gen against a five-room, use the registry number, because that is the one that has prices attached to it.

“Adjoined flat” is the jumbo flat

One model in the list needs decoding rather than describing. Adjoined flat — 413 sales since 2017, 1,346 all-time — is HDB’s registry code for what the market calls a jumbo flat: two adjacent flats joined into one.

The giveaway is the record. The top Adjoined flat sale is $1,530,000 at Blk 50 Moh Guan Terrace, Bukit Merah, in May 2026, a 150 sqm “4-room” on a 1973 lease. That is the same Tiong Bahru sale that has been reported everywhere as a jumbo record.

Unlike every other rare model here, Adjoined flats are spread across the island — Ang Mo Kio, Bedok, Bukit Merah, Clementi, Geylang and a dozen more towns — with leases mostly from the 1972 to 1980 era, and they come as four-room, five-room and Executive. Median around $770,000, at roughly $497 psf.

I have written that market up properly in my guide to jumbo flats, so I will not repeat it here. The useful thing to take from this section is the translation: if you see “Adjoined flat” on a transaction record and wonder what it is, it is a jumbo, and the two words are worth knowing because portals and the registry do not use the same one.

Rare does not mean illiquid — and it doesn’t mean liquid either

I went into this expecting a pattern. Earlier work of mine found that HDB terrace houses — the rarest housing in Singapore at 285 units — turn over faster than any HDB town, and I assumed scarcity drove it.

It doesn’t. Here is turnover, computed the same way for every model where I have both a transaction count and a unit count: sales divided by units divided by the 9.75 years from January 2017 to September 2026.

Read the Pinnacle row against the Punggol row. The most sought-after address in the HDB registry turns over at 3.26% a year. The busiest town in Singapore turns over at 3.29%. Statistically those are the same number. Owning Singapore’s most famous flat does not make it change hands any faster than owning an ordinary flat in Punggol.

And Multi-Generation — the rarest model I could count, 367 units in the entire country — turns over at 2.49%, barely above the national average. Rarity does not create liquidity. What creates liquidity is a buyer pool, and 367 units spread across three towns with a 1987 lease is a small one.

So the terrace result stands alone, and I now think it is about the product rather than the rarity: landed public housing has a distinct and motivated buyer pool that nothing else on this list has.

A small correction to my own earlier arithmetic. I previously published the terrace turnover as 4.50%. That used a slightly shorter window. Recomputed on the consistent 9.75-year basis used for every row above, it is 4.43%. The conclusion is unchanged — it is still higher than any HDB town — but the number should match across my own articles, so 4.43% is the one to use.

Three publishers cannot tell a 1987 flat from a 2013 one

This one I did not go looking for. It fell out of the data, and once you see it you cannot unsee it.

Multi Generation and 3Gen are two different models, and the registry proves it beyond argument. Their leases do not overlap — Multi-Gen is 1987 and 1988 only, 3Gen is 2018 to 2021 only. Their towns do not overlap in the way you would expect. Multi-Gen exists in three towns; 3Gen exists in nine, and has never once traded in Bishan, which is one of the three Multi-Gen towns.

Now look at what gets published.

I am not writing that to score points. I am writing it because if you are a 3Gen owner reading a guide that is silently analysing 1987 flats, every number in it — the volume, the price trend, the liquidity — is about a different product with a lease thirty-one years older than yours.

Two things I want to be equally fair about, since I went looking for errors and found some that weren’t. Qanvast’s rare-flat article quotes a $1.57m terrace sale in 2024, and that checks out exactly against the registry ($1,568,000, July 2024) — no error there. And as covered above, the “115 sqm” figure for 3Gen is the Government’s own, not a mistake by anyone repeating it.

What I could not count, and won’t guess

I can derive a unit count for Multi-Generation, Type S1 and Type S2 because HDB’s block register has fields that identify them. For three of the rare models it does not, and I am not going to fill the gap with an estimate.

And one more thing I could not establish: why HDB stopped building Multi-Generation flats. Two published explanations exist and they contradict each other — one says the studio units were not being used by the grandparents they were built for, the other says they were being rented out for income instead. Neither cites an HDB source. I could not find a primary document stating a reason, so I am telling you that both accounts exist rather than picking the one I prefer.

Rare HDB flat types: who should buy one

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