See first HDB floor plans (100 most common layouts) if you did not saw arleady. I created this additional page to post less common layouts found by me or contributed by people visiting my website, without overloading main page.
Terrible proportioned HDB layouts
Bukit Batok West Avenue 5, blk 383-395 (Goodview Gardens, built 2005), probably identical with Farrer Park blk 11-15 (2004). 4-Room Model A, probably WORST HDB layout, space-wasting hallway to bedrooms which have a pointed shape. Very small living room, about 4×4 meters and I can’t imagine how to put a dining table, TV and sofa without having kids passing in front of sofa going to bedrooms.
Sengkang, blk 297-299 (Compassvale Green, built 2001), Premium Executive Apartment, having HUGE living room and tiny bedrooms, no hallways, contrasting with Bukit Batok ones.
1960s rare HDB floor plans
TO BE ADDED
1970s rare HDB floor plans
Staircase blocks with 5-room Standard flats contains 4-Room New Generation at lift level
Staircase blocks with 5-Room Improved contains 4-Room New Generation at lift level
1980s rare HDB floor plans
Unique 4-Room Model A (109 sqm) from blk 128 Geylang East Avenue 1 (there are more blocks with 45-degrees like this)
Unique 3-Room Model A (74 sqm) from blk 410, 414, 416 Eunos Road 5 (same block have 3-room flats measuring 80, 87 and 94 sqm, possibly including recess area at end of corridor)
Shophouse floor plan, similar with 3-Room Simplified
Rare Jumbo flat formed from two 4-Room New Generation flats, making a single unit per floor with 2 entrances. Found in Woodlands blocks 115, 119, 124.
5-Room Improved Maisonette (133 sqm), only 3 blocks of this type were built in 1983 (Hougang blk 111, 122, 312) before 5-Room Model A Maisonette was introduced in same year, and replaced in 1984 with Executive Maisonette.
In Bishan there are 13 point blocks different than point blocks in other towns, featuring 5-Room Improved (121 sqm) and two types of Executive Maisonette (150 and 163 sqm) sharing top 3 floors.
1990s rare HDB floor plans
UNIQUE, 1997 Premium contract Tampines blk 498 (atrium block) composed by 4-Room Model A (106 sqm), 5-Room Improved (124 sqm), Executive Apartment (143 sqm) and at top floor Executive Maisonette (147 sqm), they being the only HDB flats designated as 5-bedrooms (other HDB flats may have 4 bedrooms + family which can be turned in 5 bedrooms too)
UNIQUE Bedok blk 140 (1998) with 5-Room Improved (121 sqm), 3 balconies! 
UNIQUE premium apartments from Bukit Batok blk 288/289 (atrium block) composed by Executive Apartment (144 sqm) and Executive Maisonette (165 sqm), EA have 3 balconies!
UNIQUE Executive Apartments from Pasir Ris donut block and Bukit Panjang
UNIQUE, HDB Penthouse Maisonettes
They are located in topmost floor of some 1980s and 1990s precincts in Bishan (52 units, up to 199 sqm), Choa Chu Kang (12 units, 182 / 215 sqm), Queenstown-Strathmore (4 units, 192 sqm), (source), Hougang (unknown number of units, 176 sqm), Pasir Ris blk 252-257 (6 units, 189 sqm) and Tampines blocks 143-147). 
Premium: Sembawang Blue Riverview (2001) with 4-Room (102 sqm), 5-Room (115 / 118 sqm), and Executive (137 sqm)
Nice-shpaed 5-room apartment with central living room, allow 4 spacious bedrooms (unlike other 5-room from similar period having 3 bedrooms and larger living room). From Toa Payoh block 122.
2000s rare HDB floor plans
Anchorvale Gardens: premium 5-Room and Executive Apartment
Treelodge @ Punggol: premium BTO with 4-Room and unusual 5-Room Loft units
Fernvale Crest: unusual narrow 3-Room floor plan
Punggol Sapphire: 5-room loft floor plan
Segar Meadows: 3-room, 4-Room and 5-Room with study that can be used as extra bedroom
JTC floor plans
Jurong Town Corporation established in 1968 and built 5 estates in parallel with HDB:
Taman Jurong, built 1964/1969-1974, most demolished in 1990s and 2000s). Earliest blocks were built by Economic Development Board in cooperation with HDB starting from 1964, then JTC took over in 1969.
Boon Lay Gardens, built 1974-1978, mixed with HDB, most demolished in 1990s and 2000s.
Teban Gardens, built 1977-1978, mixed with HDB, some demolished in 2000s.
Pandan Gardens, built 1978-1979, all survived.
Sembawang, built early 1970s, 7 blocks, demolished in 2004.
The 5-Room flats built by JTC feature 2 entrance doors!
Anyone have a floor plan of the JTC 4-Room point blocks (zig-zag ones, las one demolished in 2013) and can give me?
TEMP
Two examples of (Jumbo) Executive Apartment created from one 3-rm with one 4-rm, and one example of converting three 3-Room Simplified flats into two 4-rm flats.
href=”http://www.h88.com.sg/images/content/guides/hdb/EA-with-4-rms.jpg” target=”_blank” rel=”noopener noreferrer”>img title=”HDB Jumbo flat comprised by 3-Room and 4-Room Simplified” src=http://www.h88.com.sg/images/content/guides/hdb/EA-with-4-rms.jpg” alt=”Jumbo flat comprised by 3S and 4S flats” height=”160″ border=”0″ />
img title=”HDB Jumbo flat comprised by 3-Room and 4-Room Model A, 5-6 bedrooms possible (189 sqm)” src=”http://imagizer.imageshack.us/v2/1000x0100q90/840/floorplan.jpg”
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BTO/SERS era mix: 2-Room Studio (45 sqm) from Commonwealth View SERS, 3-Room (66 sqm) from Straits Vista BTO, 4-Room (90 sqm) from Membina Court SERS, 4-Room (90 sqm) from Kallang Heights SERS with bad-shaped living room, 4-room with central living room from unknown area. Point mouse cursor on photos for details!
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title=”HDB 2-Room Studio floor plan (45 sqm) from Commonwealth View” src=”http://www.myhometown.sg/Portals/0/Member/pet24/mum%20floor%20plan.jpg”
title=”HDB 4-Room apartment floor plan (90 sqm) from Kallang Heights” src=”http://www.myhometown.sg/Portals/0/Member/4RM_KallangFloorPlan.jpg”
THIS is how does look a block full with unsold Executive Apartment (140 sqm?) split into 2-Room (52 sqm?) and 3-Room (83 sqm), 5 sqm lobby, resulting in a fucking crazy layout! Notice window position for living room and master toilet! I am curious if they built another bomb shelter for the 2-Room! This is from Sengkang, but converted blocks are also in Jurong West.
MORE TO BE ADDED
Hi…
Could i check with you if the following design (floor plan) can be found in clementi, dover, jurong east or queenstown areas?
HDB1993-1998EA Corner (toilets are not back to back) I wasnt able to cut and paste the image here.
Regards,
Sharon
I’m staying in Bukit Batok West avenue 5, BLK390, Goodview Gardens. To me, it is a lovely place. There are different deign of gardens around each of the block, 2 pavilions are designed and built in between of blk 39388 to 390 and Blk 391 to 395. The background of the block series is the Military camp. Thats the reason why HDB created this unique strcuture to block window view from the residences.
The spacious living room has unblocked greenary view for my 5 rooms units.
I agree with you that the living room space is a bit congested for 4 room units here.
However, I DISAGREE on such way you commond it as ” possible the WORST HDB layout”. Come on, I believe if you will only choose to buy a house when you like it. Same here, WE LOVE GOODVIEW GARDENS, it is our HOME SWEET HOME !
The floorplan looks awful on the paper, but it’s not that bad to live in the unit. Or perhaps, I’m used to it having lived there for years.
Hi Do you have Blk 268 4s floor plan with two bedrooms facing the corridor?
Hi Do you have Serangoon North 4 Room NG Floor plan? Built in Year 1985
Hi, Do you have B494C Tampines 5I corner unit floor plan built during 1990s?
Hi do you have floor plan of 4A (stairs) at 4XX Pasir Ris Dr 4/6? The one with huge open balcony.
Unusual narrow 3-Room from Sengkang, does anyone know BTO name? -> This is Fernvale Crest, in Sengkang West next to Jalan Kayu.
Add blk 259 ang mo kio floor plan aka round hdb block