Renovating a bathroom: waterproofing, the 3-year rule and the plumber

A bathroom that leaks costs more than the renovation: water finds its way into the flat below. Whatever the home, the bathroom is the room where the waterproofing, and the plumber, matter most.

New HDB flats: the 3-year rule

HDB lays a waterproofing membrane under the bathroom tiles. To protect it, the bathroom and toilet floor and wall finishes in a new flat can’t be replaced for 3 years from the date the block was completed. Not from your key collection: from the block’s completion date.

In those 3 years you can still lay new floor tiles over the old ones using adhesive. Bathrooms can only be enlarged after the 3 years, with a permit, by no more than 600mm and 0.6 square metres.

Replacing a bathroom floor (HDB flats)

Once replacement is allowed, HDB requires:

• an HDB permit, applied for by your HDB-registered contractor;
• a waterproofing screed and membrane, turned up at least 150mm against the walls, kerbs and pipes;
• UPVC floor trap gratings with a long collar;
• a water test by you and your contractor once the new floor is done.

The void under a long bath or shower tray must not be filled with cement mortar or anything else, and weep holes are needed. Spa baths must be ready-made, sit inside the original bathroom, and weigh no more than 400kg in total, water and all.

The plumbing

• Toilet bowls (installing, changing or moving them) and sanitary pipes need a PUB Licensed Plumber. HDB adds that vent pipes can’t be removed.
• Water pipes being laid, altered or replaced also need a Licensed Plumber.
• Anyone may replace taps, mixers, shower hoses and heads, and cistern flushing parts, according to PUB.

Power

In HDB flats, exhaust fans are allowed only in bathrooms, and all wiring must be done by an EMA-licensed electrical worker. Water heaters connected to the gas supply need a licensed gas service worker.

Condos and landed homes

There’s no HDB-style 3-year rule, but the waterproofing matters just as much, especially above someone else’s home. BCA lists replacing floor and wall finishes as an insignificant building work, so no plans go to BCA, but your condo by-laws may require MCST approval and set conditions. The licensed-plumber rule applies everywhere.

The order of work

1. Hack out old tiles and fittings (in HDB flats, weekdays 9am to 5pm only).
2. Plumbing and electrical rough-ins.
3. Screed and the waterproofing membrane.
4. Tiling, then sanitary ware, taps and accessories.
5. The water test (HDB requires one once a new bathroom floor is done), and check that water drains to the floor trap.

SpaceToReno is run by the team behind Junk to Clear, which also handles renovations. Where a guide links to Junk to Clear or a sister site, it’s because that step calls for the service, and the sentence says so. Enquiries sent through the form go to the same team. How SpaceToReno works