Bathroom Waterproofing When Renovating in Malaysia: Membranes, Ponding Tests and Leaks Below (2026)

中文 · Bahasa Melayu · Bahasa Indonesia

By Jason Lim, REN 84424 · IQI Realty · Checked on 15 November 2026

This guide is for owners renovating a bathroom in Johor Bahru or elsewhere in Malaysia, and for buyers from Singapore, Indonesia, India and China who want to know what they are taking on. The short answer: tiles and grout are not waterproof. What keeps water out of the slab is a membrane under the tiles, laid on a floor that falls to the drain, turned up the walls and tested by flooding the floor before any tile goes down. In a condo, a failed membrane usually shows up as a stain on your neighbour’s ceiling, and the law presumes the leak is yours to fix.

Why bathroom waterproofing matters so much

When bathroom waterproofing fails, water moves through the screed into the slab and appears somewhere else: a ceiling stain below, a damp skirting next door, or peeling paint outside the bathroom. The tiles above may still look perfect.

Leaks between floors are a common strata complaint. The Star reported in February 2023 that Kuala Lumpur City Hall received 1,265 leak reports in 2022, up from 489 in 2018, and that inter-floor leaks were the second most common complaint at the Strata Management Tribunal after unpaid maintenance fees.

The same article gave a rough guide: a fast drip suggests a supply pipe, a steady drip with a foul smell a waste pipe, and a steady odourless drip with white mineral deposits (efflorescence) failed waterproofing. My guide to damp, mould and wall seepage covers the other causes.

How a wet-area waterproofing system works

A waterproofed bathroom floor is a set of layers. If one is missing or done badly, the others cannot make up for it.

Layer	What it does	What to ask or check
Screed laid to falls	Shapes the floor so water runs to the floor trap	The fall is built into the screed, not just the tile bed
Sealant or bond breaker at corners and joints	Lets the membrane flex where the floor meets the wall	A continuous bead along the wall-floor junction
Primer and membrane	The actual water barrier	On a clean, sound base; number of coats; turned up walls and kerb; sealed to the trap and pipes
Ponding (flood) test	Proves the membrane holds water before it is covered	Done after the membrane cures and before any screed or tile
Protection screed or tile bed	Protects the membrane from tile work	No nails, drilling or sharp tools through it
Tiles, grout and silicone	Finish and first line of defence	Grout is not waterproof; joints at corners and around fittings need sealant

Membrane types in plain terms

You need not pick a product, but know which family your contractor uses, because curing time and flexibility differ.

Type	How it goes on	Points to know
Cementitious (often polymer-modified, two-part)	Brushed or trowelled in coats, sometimes with a mesh	Common in Malaysian bathrooms; bonds well to concrete; needs proper curing between coats
Liquid polyurethane or acrylic	Rolled or brushed in coats to a set thickness	Flexible, good at corners; thickness depends on the number of coats
Sheet membranes	Pre-made sheets bonded down with lapped and welded seams	Even thickness and no curing wait, but seams and outlets must be sealed carefully
Fibreglass-reinforced resins	Built up in layers with glass fibre	Strong but less flexible; need a rigid base and attention at changes of direction

BRANZ says each coat of a liquid membrane should cure fully before the next and before the flood test, “generally at least 24 hours at 20°C”. Johor’s humidity can slow curing, so follow the maker’s data sheet.

Falls, upturns and the weak spots

Most leaks start at edges and openings. Ask how each of these will be handled before you agree a price.

• Floor falls. Water must run to the floor trap and not sit in corners. BRANZ, a New Zealand building research body, gives a minimum fall of 1:60 for enclosed showers and 1:50 for level-access showers. I found no published Malaysian figure for home renovations, so agree the fall in writing and check it with water before tiling.
• Upturns at walls and kerbs. The membrane should continue up the walls so water cannot get round its edge. Singapore’s HDB requires at least 150 mm against walls, kerbs and pipes when flat owners redo bathroom floors.
• The floor trap. The membrane must bond to the drain flange so water in the tile bed still reaches the drain.
• Pipe penetrations. Seal around pipes, with the membrane carried over the seal.
• The doorway. A kerb, step-down or water stop keeps water from tracking under the next room’s floor.
• Overlaying old tiles. New tiles over old ones do not repair a failed membrane underneath. HDB, for example, limits overlays to one existing layer and 13 mm including adhesive, with no tampering with the floor trap.

Western Australia’s building regulator found the same weak spots, falls, drain flanges, sealant and membrane protection, in its wet-area inspections (Industry Bulletin 134, January 2020).

The ponding test: the step you should never skip

A ponding test (also called a flood test) is the simplest safeguard in a bathroom renovation. BRANZ advises doing it after the membrane cures and before tiling, while a leak can still be fixed.

1. Block the floor trap, with a temporary dam at the doorway if there is no kerb.
2. Flood the floor to cover the highest point and mark the water line.
3. Wait. Leak investigators in The Star’s report monitored a flooded wet area for 24 hours; ask for at least that, unless the membrane maker sets a longer period.
4. Check below and beside. In a condo, ask the owner below to let someone see the ceiling; in a house, check the ground-floor ceiling and adjoining walls.
5. Record it. Take dated photos at the start and end.
6. Fix and retest if the level drops or damp appears.

Condo bathrooms: approvals, the unit below and who pays

• Approval first. Standard by-law 27 in the Third Schedule of the Strata Management (Maintenance and Management) Regulations 2015 bars renovation without the management’s prior written approval, and allows it to ask for a deposit. By-law 28 adds that moving plumbing or sewerage pipes needs both the management and the authority. Many renovation forms I see in JB ask for the waterproofing method for wet areas. See my guide to condo renovation rules and deposits.
• The legal presumption. Section 142 of the Strata Management Act 2013 (Act 757) presumes that dampness on a ceiling comes from the unit or common property above, unless proven otherwise.
• Your bathroom, your repair. Under Part XV of the 2015 Regulations, a leak traced to waterproofing, a floor trap or pipes that serve only the unit above is that unit’s defect. The management must inspect within 7 days of a written complaint and issue a Form 28 finding within 5 days after that; the owner named must start repairs within 7 days of receiving it.
• If it stalls. Disputed findings go to the Commissioner of Buildings at your council (MBJB, MBIP, MBPG or MPKu), and claims can go to the Strata Management Tribunal, which hears claims up to RM250,000 for a RM100 residential filing fee (KPKT, July 2025).

A bad membrane can mean paying for the ceiling below as well. My guide to a condo water leak from the unit above walks through the process from the other side.

Landed homes: upstairs bathrooms and shared walls

In a double-storey house the room below is your own, but first-floor bathrooms still need the full system and a ponding test, and a bathroom against a shared wall can push damp next door. My guide to party walls in terrace homes covers that.

Moving a toilet, floor trap or shower point usually means new pipe routes, and changes to sewerage or structural parts can need council approval. Check my guide to renovation permits in Johor Bahru and when you need an architect or engineer before you sign off on a new layout. If the pipes themselves are old, see plumbing problems in older homes.

New homes: defects first, renovation second

If you have just collected the keys to a new home, the developer is responsible for defects during the defect liability period, which has been 24 months from vacant possession under the statutory sale agreements since late 2007 (Schedule G for landed homes, Schedule H for strata). A leaking bathroom found in that time is the developer’s to fix under the agreement.

• Test before you renovate. Ask the developer to flood-test the bathrooms at handover, or check below and beside during heavy use in the first weeks. My vacant possession defect checklist lists what else to check.
• Report in writing, then wait for the repair. Hacking the floor first can let the developer argue that your contractor caused the problem.
• Keep the evidence. If the developer does not act, the Tribunal for Homebuyer Claims is the usual route. Leaks found after the period ends are covered in my guide to latent defects after the DLP.

For the order of work after handover, see renovating a new house step by step.

Hiring a contractor and getting a warranty

• Check CIDB registration. Section 25 of the Construction Industry Development Board Act 1994 requires contractors to register, and CIDB said in March 2024 that unregistered contractors face fines of RM10,000 to RM100,000.
• Write the specification into the quotation. Membrane type, number of coats, upturn height on walls, kerb and shower, how the floor trap is sealed, the fall, and a ponding test before tiling, with you or your representative present.
• Ask for photos at each stage, from the hacked slab to each coat and the test.
• Pay by stages, and keep a payment due after the test and the final tiling.
• Get a written warranty on the waterproofing. No law sets a length for home renovations, so the contract decides. Note who pays for retiling if it is used.

If the work fails and the contractor will not return, the Tribunal for Consumer Claims hears home-renovation claims up to RM50,000 for a RM5 filing fee, and the Consumer Protection Act 1999 implies that services are done with reasonable care and skill (KPDN, August 2024). See renovation contractor disputes and hiring an interior designer or contractor in JB. Many home insurance policies treat gradual leaks differently from sudden pipe bursts, so read your wording; my home insurance guide explains the basics.

Buying a subsale: signs of failed waterproofing

When I view older units with buyers, the bathroom is one of the first rooms I check. Signs worth asking about:

• Stains, bubbling paint or a patched false ceiling under the bathroom, in the unit below or on the floor below in a house.
• Damp or mouldy skirting and peeling paint on the wall outside the bathroom.
• Grout that stays dark long after a shower, hollow or loose tiles, and water ponding away from the trap.
• White powdery deposits on exposed concrete or a musty smell that does not clear.
• New tiles in an old bathroom: ask what was done and whether a warranty passes to you.

Ask the seller and the management office whether there have been leak complaints or Form 28 findings for the unit, and see my subsale house inspection guide and questions to ask at a viewing. Budget for a redo with my renovation costs guide.

Where to buy if this matters to you

If you want to avoid a bathroom redo, focus on newer homes where the defect period may still be running, or older homes where you can see recent, documented work. Area guides:

• Iskandar Puteri: many newer condos and landed estates, some handed over recently.
• Mount Austin: a mix of newer condos and established landed homes.
• Tebrau, Setia Indah and Molek: established neighbourhoods where renovation history varies house by house.
• Skudai, Tampoi and Kempas: older terrace stock alongside newer projects.
• Permas Jaya and Senibong: east-side condos and waterfront projects.
• Bukit Indah and Gelang Patah: landed estates near the Second Link.

Compare them on my JB property map.

More Johor living guides: Condo leak from the unit above · Damp, mould and wall seepage · Hiring a contractor in JB · Water heaters and safety · Who pays repairs: landlord or tenant

Frequently asked questions

Do I need to waterproof a bathroom when I change the tiles?

If you hack the floor tiles down to the screed or slab, yes. Removing tiles usually damages the old membrane, so a new one should go down, be turned up the walls and be ponding-tested before the new tiles are laid.

What is a ponding test for bathroom waterproofing?

The floor trap is blocked and the bathroom floor is flooded after the membrane cures, before tiling. The water level is marked and the ceiling below is checked. Leak investigators described in The Star monitor a flooded wet area for 24 hours.

Who pays if my bathroom leaks into the condo unit below?

Under the Strata Management Act 2013 a ceiling leak is presumed to come from the unit above. If the management’s Form 28 finding traces it to your waterproofing, floor trap or pipes serving only your unit, you must repair it, starting within 7 days.

Can I tile over old bathroom tiles instead of hacking them?

It is sometimes done, but it does not fix a failed membrane underneath and can raise the floor above the trap. Singapore’s HDB, for example, allows only one existing layer and 13 mm including adhesive. Check your condo rules first.

Does my new house’s defect period cover bathroom leaks?

Generally yes. Under the statutory Schedule G and Schedule H agreements, the developer fixes defects reported within 24 months of vacant possession. Report the leak in writing before renovating so the developer cannot blame your contractor.

Do I need approval to renovate a condo bathroom in Johor?

Yes. The standard strata by-laws require the management’s prior written approval, and moving plumbing or sewerage pipes also needs the local authority. Expect a renovation deposit and to state the waterproofing method.

Renovating or buying in JB?

Tell me the project or area you are looking at. I can check a unit’s leak and renovation history with the seller and management before you offer, and point out bathroom issues at viewings. You can also book an appointment for viewings, or a Zoom consultation if you are abroad.

Sources: The Star, “In a fix over leaks” (leak reports, causes, 24-hour flood test), 17 February 2023; BRANZ, “Waterproofing tiled showers” (membrane types, falls, curing, flood test), updated 19 May 2026; Government of Western Australia, Building and Energy, Industry Bulletin 134: Improving compliance of wet areas, 27 January 2020; Housing & Development Board (Singapore), renovation guidelines for building works (150 mm membrane upturn, overlay limits), checked November 2026; Building and Construction Authority (Singapore), Good Industry Practices: Waterproofing for Internal Wet Areas, second edition, contents page checked November 2026; Strata Management (Maintenance and Management) Regulations 2015, P.U.(A) 107/2015, Part XV and Third Schedule by-laws 27 and 28 (copy published by DBKL), checked November 2026; Strata Management Act 2013 (Act 757), section 142 (copy published by DBKL), checked November 2026; Attorney General’s Chambers, Laws of Malaysia Online: Act 757; Construction Industry Development Board Act 1994 (Act 520); Consumer Protection Act 1999 (Act 599), checked November 2026; KPKT, Soalan Lazim Tribunal Pengurusan Strata, updated 9 July 2025; The Sunday Star, on the 24-month defect liability period (reproduced by the National House Buyers Association), 16 December 2007; CIDB, reminder to register and renew contractor registration (Act 520, section 25), 20 March 2024; KPDN, Tribunal for Consumer Claims Malaysia, Frequently Asked Questions, updated 30 August 2024; Consumer Protection Act 1999 (Act 599), sections 53 to 56, reprint as at 1 November 2021 (KPDN copy)

Jason Lim, REN 84424, IQI Realty Sdn. Bhd. E (1) 1584/6. General information checked on 15 November 2026, not engineering, legal or insurance advice. Every bathroom is different; get a CIDB-registered contractor or a licensed professional to inspect, and confirm rules with your management office, the council, your lawyer or your insurer before you act.