The short answer

You can install a bathtub in an HDB bathroom. The rules depend on how you install it:

  • Freestanding tub on the existing floor: the tub stands on the finished tiles and drains into the floor trap. You don't hack tiles or change the floor, so the bathroom renovation rules below mostly don't come into play.
  • Built-in tub: usually means hacking, new waterproofing and a permit, and it can't be done in the first 3 years of a new block.

HDB's rules for installing a bathtub

HDB's plumbing guidelines call a bathtub a "long bath". To install one:

  • You can't extend the toilet to fit the bathtub.
  • The void under the bathtub must be kept. Don't fill it with cement mortar or other materials.
  • Provide an inspection opening for future maintenance.
  • Provide weep holes.
  • Don't tamper with the floor slab.

The void, inspection opening and weep holes apply to tubs that are boxed in. A freestanding tub stands in the open, so you can already reach everything under and around it.

New flats: the 3-year rule

In a newly built flat, you have to wait 3 years from the completion of the block before you remove any wall or floor finishes in the bathrooms. The rule protects the waterproofing. Until then you can lay new tiles over the existing ones.

This is why many new flat owners choose a freestanding tub: it doesn't need any tiles removed.

After 3 years: permits for bathroom works

You need an HDB permit to:

  • Replace the bathroom floor finishes. The finishes and screed together can be at most 50 mm thick, you must use pre-packed waterproofing screed and a waterproofing membrane, and the membrane goes at least 150 mm up the walls, kerbs and pipes.
  • Replace the bathroom wall finishes (at most 25 mm thick, including plaster).
  • Enlarge the bathroom: by at most 600 mm and 0.6 m², and only as a dry area, for example for a wash basin or shelves. The bathtub itself still has to fit in the original bathroom.

What about weight?

HDB's guidelines don't give a separate weight limit for bathtubs. The closest figure is for spa pools: the total weight, including the water, motor and accessories, must not exceed 400 kg, and the spa pool can only go in the bathroom HDB built.

You will also see "150 kg" quoted online. In HDB's building works guidelines, 150 kg is the limit for installing equipment without a permit. It isn't a rule written for bathtubs.

Most of a full bathtub's weight is the water, at about 1 kg per litre. Acrylic tubs are light. Solid surface (stone resin) tubs are heavier, and cast iron and solid stone tubs are heavier still. Ask us for the empty weight of any tub before you order, and check with HDB if you are planning a very heavy tub.

Plumbing: use a licensed plumber

Water service and sanitary works must be done by a PUB Licensed Plumber. HDB notes that a handyman without a PUB licence can still do simple plumbing works.

Checklist before you buy

  • Measure the space for the tub, plus the narrowest door, corridor and lift on the way to the bathroom.
  • Find the floor trap: the tub's waste pipe needs to reach it.
  • Decide on the tap: floor-standing or wall-mounted.
  • Check that your water heater can fill the tub with hot water.
  • Plan where you will shower, or add a shower screen.

Not sure if a tub fits? Send us your measurements and a photo on WhatsApp and we'll check for you, or browse our small bathtubs for HDB bathrooms.