Why flat type matters for renovation

The flat type determines more than just how many rooms you have. It shapes the structural wall layout (which walls you can and cannot touch), the location of the household shelter (bomb shelter), wet-area plumbing positions, and how much flexibility you have for an open-concept rework. A 3-room resale from the 1980s has very different walls and proportions from a 3-room BTO built in the 2020s — even if both carry the same label.

Before engaging any contractor or interior designer, get your actual floor plan. It is the single most important document for accurate renovation planning.

The six main flat types

HDB classifies flats by the number of rooms, where "rooms" includes bedrooms but not the living/dining area. The table below shows commonly cited size ranges — treat these as approximate guides, not guarantees. Your unit's exact internal floor area (net lettable area) is shown on your official HDB floor plan and title deed; confirm it there.

BTO vs resale: the floor-plan difference that matters

Built-to-Order (BTO) flats are newly constructed units you apply for from HDB before they are built. Resale flats are existing units bought on the open market — they may be anywhere from a few years to over 40 years old.

From a floor-plan and renovation standpoint, the differences are significant:

• Layout generation: Older resale flats (built in the 1970s–1990s) often have enclosed kitchens, smaller bathrooms, separate utility rooms, and sometimes larger individual bedrooms. Newer BTOs lean toward open-plan living/dining, smaller but better-proportioned rooms, and prefabricated bathroom components.
• Wall types: Older flats used more in-situ reinforced-concrete walls. Newer BTOs use a mix of RC structural walls and lightweight block/drywall partitions. This affects what can be hacked — always check with HDB and a licensed contractor before assuming a wall is non-structural. See our guide on hacking and partition walls for details.
• Wet-works rules: Flats less than about 3 years old (from TOP date) are subject to stricter restrictions on wet works such as retiling and hacking of floor screeds. This applies to new BTO flats you just received keys for. Confirm current rules with HDB and your licensed contractor.
• Size variation: A resale 4-room can range widely in actual floor area depending on when and where it was built. Do not assume the type name tells you the sqm — read your floor plan.

How to read an HDB floor plan

An HDB floor plan shows the unit boundary, room layout, and key structural elements. Here is what to look for:

• Walls: Thick solid lines (usually RC/concrete) are structural and cannot be hacked. Thinner lines or hatched fills may be non-structural lightweight walls — but verify; never assume.
• Household shelter (HS): The bomb shelter, typically near the entrance or service area, has reinforced concrete walls on all sides and must not be modified. Its location is always marked on the official plan.
• Wet areas: The kitchen, bathrooms, and utility/yard areas. Plumbing riser positions (shown as circles or squares on the plan) cannot be moved; your fixtures must connect to these fixed points.
• Door and window openings: Shown as arcs (doors) and thin parallel lines (windows). Opening positions in structural walls are fixed; non-structural partitions can sometimes have openings added or removed with the appropriate permit.
• Dimensions: Official plans show wall-to-wall internal dimensions. Use these — not the sqm total — when planning furniture and cabinetry. A sofa, bed, or kitchen island needs to fit the actual room width, not the nominal flat size.

Where to get your official HDB floor plan

There is one authoritative source: HDB's official e-Services portal. Here is how to access it:

• My HDB Page (MyHDBPage): Log in at the HDB website using your SingPass. Under "My Flat," look for the floor plan section — you can view and download your unit's official floor plan as a PDF. This is the most direct route for current owners.
• HDB e-Services portal: The HDB website (hdb.gov.sg/eservices/) provides a range of services including the ability to request or purchase a floor plan for your unit. Some floor plans are available for free download; others may carry a small administrative fee — confirm at the time of access.
• OneMap: Singapore's national map platform (onemap.gov.sg) is developed by the Singapore Land Authority and integrates HDB block data. You can search by block/street and view typical floor-plan layouts for many blocks — useful for research, though it shows typical plans for the block type, not necessarily your unit's as-built state.
• BTO brochures: If you are buying a new BTO flat, HDB publishes detailed floor plans in the sales launch brochure. These are downloadable from the HDB Flat Portal during the sales exercise.

Block, unit, and storey: understanding HDB addressing

An HDB address has three levels of specificity that affect your renovation planning:

• Block: The building number (e.g. Block 123). A single block may contain multiple flat types across different stacks. Not every unit in the same block has the same layout.
• Stack / unit number: Units in different stacks (e.g. #01-01, #01-45) face different directions and may have mirror-image layouts or different corner configurations. Corner units often have extra windows but also more external walls — relevant for thermal comfort, aircon placement, and window-facing sun.
• Storey: The floor level affects natural ventilation, noise (from ground-level amenities or overhead), structural loading, and sometimes lease value. For renovation, high-floor units may have slightly different ceiling heights in older blocks.

When you plan your renovation, always reference your specific stack and unit number — not just the flat type or block number — when reviewing floor plans or discussing layouts with contractors.

Planning your renovation from the floor plan

A scaled floor plan is the foundation of any renovation. With your actual room dimensions in hand, you can:

• Determine whether an open-concept kitchen is feasible (and which walls are structural).
• Plan furniture layout at true scale, avoiding costly mistakes like a bed that blocks a door swing.
• Mark out where aircon piping, electrical points, and data cabling need to run — before walls are closed up.
• Identify the household shelter position so you can design around it rather than into it.
• Share an accurate plan with your interior designer or contractor for quoting — vague sketches produce vague quotes.

If you want to move beyond a static PDF, you can upload your HDB floor plan to StoreySG and rebuild it at true millimetre scale in your browser — no installation required. You can then use natural-language commands to place furniture, swap finishes, and try different layouts before committing to any physical work. The tool also lets you export a CAD-ready DXF of your plan, which your contractor or interior designer can open in AutoCAD or a similar program. Read more in our guide on precise CAD floor plans.

Before any renovation begins, check whether your planned works require an HDB renovation permit. Our HDB renovation permit guide covers what needs approval, how to engage a licensed contractor, and the rules around permitted renovation hours.