01 / Roofs
Exposed roofs
Full sun, so the membrane must hold colour and elasticity under permanent UV — and stay continuous through every outlet, upstand and plinth.
Waterproofing Systems Singapore
Waterproofing systems for Singapore roofs, decks and wet areas.
Rayson makes the system, publishes its data and quotes the job. Applicators in Rayson's network assess the site and install it, under the workmanship warranty set out in Rayson's quotation; in an HDB flat, a contractor on HDB's Directory of Renovation Contractors quotes instead. From an HDB or condo toilet to a landed roof, a car porch or a car park deck, four things decide which system: the surface, the exposure, the detailing and the traffic, and the 2026 cost ranges are on this page.
Request a site assessment through a Rayson applicator Request material pricing and data sheets Find the page for my surface
HDB & condo toiletsRoofs & car porchesCar park decks2026 cost ranges3–5 year material warranty
Reviewed: October 2026
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- The surface, wide
- The leak or problem, close
- The approximate size
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Reply within one working day, Mon–Fri. Rayson quotes; an applicator from its network inspects and installs.
The short answer
A waterproofing specification is decided by four things — not by the product name.
Answer them in order and the shortlist writes itself. Skip one, and the system fails at the point you skipped.
- 01 The surface
Concrete, screed, tile, metal or an old membrane each need a different primer, and each has a soundness and moisture threshold below which nothing holds.
- 02 The exposure
Permanent sun demands a UV-stable chemistry. Standing water, a contained liquid, chemicals or wash-down heat each change the answer.
- 03 The detailing
Count the upstands, outlets, penetrations, terminations and joints. A surface dense with details rewards a seamless liquid system.
- 04 The traffic
Trolleys, forklifts and turning tyres mean a wearing layer above the membrane — waterproofing on its own is not a wearing surface.
Go to the depth
Four surfaces. Four different waterproofing decisions.
Each fails differently, so each has its own page. Pick the one you are standing on.
02 / Car parks & porches
Decks that carry traffic
Waterproofing is half the job: above the membrane a wearing surface has to survive turning tyres and keep its grip when wet. A landed-home car porch is the same job in miniature, sitting over living space.
03 / Wet areas
Toilets and bathrooms
The membrane vanishes under tile or screed and is never inspected again. The trap, the turn-ups and the penetrations decide it, and a 24-hour flood test proves it before a tile goes down.
04 / Tanks & containment
Liquid-tight linings
The contained liquid sets the chemistry, not the weather, and liquid-tight is the whole specification — usually a specialist sprayed lining.
Coating vs membrane
Liquid-applied and sheet fail in opposite places.
A liquid coating is built on site: seamless, but its thickness depends on workmanship. A sheet arrives at factory thickness, but every seam is a path. Neither is more waterproof — they are strong in different places.
| Liquid-applied coating | Sheet membrane | |
|---|---|---|
| How thickness happens | Built coat by coat on site — workmanship is the variable | Set in the factory — consistent whoever lays it |
| Joints | None in the field; the film is continuous | Every lap and termination is a joint, and a joint is a path |
| Complex detailing | Follows coves, outlets and changes of plane directly | Cut and taped around geometry — the slowest, riskiest part of the job |
| Strongest at | Exposed, detail-heavy, trafficked surfaces; simple local recoat | Buried tanking and podium decks under hydrostatic pressure |
| Inspection and repair | Visible; a wear zone is recoated locally | Hidden — water travels under it, far from the visible leak |
| Defeated by | Ponding from failed falls, live cracks, saturated substrates, negative-side pressure — correct these first, either way | |
Where it actually fails
Detailing decides the result. The open field rarely leaks.
Waterproofing rarely fails in the middle of a sound slab. It fails where the surface turns, drains, moves or meets another material.
- 01Upstands
The membrane turns up the wall and has to stay up; a cove removes the sharp angle that thins a liquid film and cracks a folded sheet.
- 02Outlets
Water concentrates at the drain, so the detail is reinforced and dressed into the outlet — never stopped short of it.
- 03Penetrations
Pipes, conduits, handrail feet and plinths each need their own collar. Count them before pricing: they are why equal areas are not equal jobs.
- 04Terminations
Every edge where the system stops must be mechanically secure and sealed above the water line, or water gets behind it and travels unseen.
- 05Movement joints
Joints keep moving after the membrane is down, so they need a detail designed to move — plain film only defers the tear.
Live cracks, saturated substrates, negative-side pressure and chronic ponding are corrections, not coatings. Rayson says so before specifying a system.
What it costs
Price depends on area, condition and detailing.
Compare quotations on the same area, preparation, system and detailing scope, and confirm whether they cover materials only or installation as well. TDS consumption supports a theoretical material estimate; surface condition, application losses and wastage affect the quantity required.
Waterproofing coatings Rayson supplies
Six liquid-applied waterproofing membranes, formulated in Singapore. Choose the role, then read the data.
A waterproofing coating — often searched for as waterproofing paint — is a liquid that cures into the membrane on the surface it is applied to, with no sheets and no laps. It is not a tin of damp-proof wall paint: a membrane is applied at a published consumption to a measured thickness over a primer (the difference, set out in full). Rayson supplies six: a one-part water-based membrane for the tiled toilets, bathrooms and balconies of homes, an aliphatic polyurea coating for exposed roofs, a one-part acrylic coating for pitched and tiled roofs and external walls, a roller-applied polyurea membrane for decks and heavier-duty wet areas, and two hot-spray polyureas for linings. Starting routes, not a specification — open the TDS before committing to preparation, film build or timing.
SealForce WB20
One-part, water-based, polyurethane-modified membrane rolled straight from the pail in two coats beneath the tiles of toilets, showers, bathrooms and balconies — no primer, no mixing, low odour in an occupied home.
SealForce RC40
Two-component, cold-applied aliphatic polyurea membrane for suitable exposed roofs — UV-stable, walkable, applied by roller, brush or airless spray.
SealForce AC10
One-part, water-based acrylic membrane rolled on from the pail over its SealForce AP05 primer and left exposed on roofs that drain freely, old roof tiles and external walls — UV-resistant, elastic and permeable to water vapour. Not for roofs that pond or are walked on.
SealForce RC30
Two-component, roller-applied polyurea-based liquid membrane for suitable deck build-ups, roofs and heavier-duty wet areas, including under-tile work where a two-component membrane is specified.
SealForce SP200
Hot spray-applied, 100% solids pure polyurea for suitable concrete and steel linings — heated plural-component equipment and specialist applicators only.
SealForce SP210
Hot spray-applied pure polyurea lining for suitable tank, reservoir and containment work; its drinking-water contact certification is set out in the product data.
Recent trial application
A hacked HDB toilet in Hougang, membrane to flood test, September 2026.
A pre-launch trial batch of SealForce WB20, photographed between the coats and during the flood test. Reference for the wet-area duty; the product is part of Rayson's upcoming release.
Still not sure which route?
Describe the surface. We will tell you which system it needs.
Send overview and close-up photos, the structure, approximate area, where water appears and your access window. You get an initial response within one working day — including when the honest answer is a repair or a drainage fix rather than a coating.
Rayson manufactures coating materials, quotes installation jobs and has them carried out by applicators in its network using Rayson products. Active-leak diagnosis and waterproofing repair need an appropriately experienced applicator. Tell us the problem so we can review material suitability and arrange an inspection. Confirm the scope and responsible parties before work begins.
Keep reading
The pages that answer the next question.
Wall cracks and seepageRead the crack: moving, seeping or structural, the repair for each, who repairs an HDB, condo or landed wall, and façade-inspection rectification Window leaks and resealingThe five places a window leaks in driving rain, how resealing is done, the published cost per metre, and who is responsible Industrial roof waterproofingFactory and warehouse roofs: laps and fasteners, box gutters, work phased around production, material per 1,000 m² Membrane types comparedTorch-on, liquid, cementitious, crystalline, sheet and polyurea — where each fits and fails Concrete roof waterproofingThe assessment that decides the outcome, then the build-up step by step Car park deck waterproofingRooftop, intermediate and covered decks need three different build-ups Why roof waterproofing failsEight causes, the signal for each, and the fix that is not a thicker coat How long waterproofing lastsWorking life by system and exposure, and when a bathroom is due for redoing Landed home waterproofingCar porch, roof terrace, balcony and planter — what fails and how each is done Bathroom and wet-area waterproofingUnder the tiles, at the trap, up the wall — and leaks from the unit above Who pays for a ceiling leakWater seepage from the unit above: HDB, condo and landed rules, and why the repair is done upstairs Choosing a waterproofing contractorSeven questions to ask and the twelve lines a quotation must show What waterproofing costs2026 Singapore ranges for toilets, roofs and leak injection, and how to compare quotes fairly
Plan your project
Product Selector
Answer four questions about your surface and conditions to shortlist suitable Rayson systems.
Find your systemCoverage Calculator
Estimate material quantities from your floor area, coats and coverage rate.
Estimate quantitiesTDS Library
Open technical data sheets for every Rayson product — no forms, no gating.
Open the libraryFrequently asked questions
What is a waterproofing coating?
A waterproofing coating goes on as a liquid and cures into a seamless film, so it follows upstands, drains and penetrations without laps. Thickness is built on site, so consumption per coat and the number of coats decide the result — which is why Rayson publishes coverage in every TDS.
Waterproofing coating or membrane — which should I use?
Neither is inherently more waterproof. A liquid coating suits exposed, detail-heavy, trafficked surfaces where seamless detailing and easy local recoat matter. A sheet membrane suits buried work under sustained hydrostatic pressure and gives factory-consistent thickness — but every lap is a potential path, and a failure under a hidden sheet travels far from the visible leak. Many Singapore buildings use both — a sheet in buried and podium zones, a liquid coating on exposed decks, parapets and complex details.
Which waterproofing system should I use for my surface?
Answer four questions in order: what the surface is, what exposure sits above it, how much detailing it has, and what traffic it carries. Exposed roofs point to a UV-stable liquid membrane such as SealForce RC40, or to the one-part acrylic SealForce AC10, over its SealForce AP05 primer, where the roof is pitched or tiled and drains freely; toilets, bathrooms and balconies beneath tiles to the one-part water-based SealForce WB20; deck build-ups and heavier-duty wet areas to a roller-applied polyurea membrane such as SealForce RC30; tanks and containment to a specialist spray polyurea such as SealForce SP200 or SP210. Confirm any route against the TDS.
Does Rayson have a membrane for HDB toilets and bathrooms?
Yes. SealForce WB20 is a one-part, water-based, polyurethane-modified membrane for the concealed layer beneath the tiles of toilets, showers, bathrooms and balconies: two coats at 0.4 mm wet film each, about 0.56 kg/m² per coat, touch dry in under an hour, flood-tested 24 hours after the final coat. It is applied to the prepared screed after hacking, not over existing tiles, and an applicator in the Rayson network carries out the work.
Can a waterproofing coating be applied over an existing coating or membrane?
Only where the existing layer is sound, dry enough, clean and compatible. Loose, waterlogged or debonded areas must be removed and repaired first; an adhesion check and a small trial area settle the preparation.
When is a waterproofing coating the wrong answer?
When it is used to cover a problem it cannot solve. Ponding from failed falls, live structural cracks, saturated substrates and negative-side pressure defeat liquid systems — and sheet membranes too. Correct the falls, the crack or the water source first.
What drives waterproofing cost in Singapore?
Singapore renovation and home-services platforms' guides checked in September 2026 put roof waterproofing at S$8 to S$50 per m² by system plus S$1,000 to S$3,000 of labour on a standard residential roof, a localised patch at S$200 to S$800, and the basic works of one HDB bathroom, hack, waterproof and tile, at about S$3,000 to S$9,000. PU injection for a slab crack runs about S$300 to S$1,200 per job in one waterproofing contractor's published 2026 guide; detail work and full re-membranes are quoted on inspection. Within those ranges, substrate condition, access and detailing decide the price: upstands, outlets, penetrations, terminations and joints add labour and material. Compare quotations on the same preparation, system and detailing scope; published TDS consumption supports a theoretical material estimate. The waterproofing cost guide carries the tables and their sources.
What warranty does Rayson give, and what does the applicator give?
Two separate warranties. Rayson warrants its SealForce membranes against manufacturing defects from the date of supply: three years for SealForce WB20 beneath tiles in wet areas, and five years for the SealForce polyurea roof and deck membranes, provided the material is stored and applied per the technical data sheet and flood-tested before it is covered; the remedy is replacement material. The workmanship warranty is set out separately in the quotation. Ask for both in writing.
Not sure which system fits your project?
Tell us your surface, area and timeline — our Singapore technical team will recommend a practical system and price it fast.