Balcony leaks: the stack, the scupper, and the door track

Last updated 31 October 2026.

Balcony water in Singapore has three honest exits: the floor waste or stack, the scupper through the kerb, and, on some sliding doors, a weep that lets water out of the track. Tile laid over a scupper, a planter sitting on the outlet, or a bead of silicone across the track turns the balcony into a tray. The bedroom ceiling at the door head then stains, and the quotation that arrives is for a full membrane. Sometimes that quotation is right. Often the outlet was simply buried.

Read HDB’s building-works line before you copy a bathroom specification onto an open balcony. For a kitchen and an open balcony, pre-packed waterproofing screed is required before new floor finishes. The membrane, with an upturn of at least 150mm, is required only around the sanitary stacks, for an area of 400mm radius. That is a local detail at the pipe, not a continuous shower membrane across the whole slab. A contractor who prices “same as toilet” is selling a different system from the one the guideline names. If the leak is at the stack, that 400mm detail is the conversation. If the leak is at the scupper or the door, a full membrane will not be what fixes it, and we will not invent a square-metre price for one.

A useful rain test needs a dry start and a shut door. Photograph the scupper from the balcony side and, if you can do it safely without leaning past the railing, note whether water stands against the kerb after the rain eases. Puddles that remain an hour later are a fall problem or a blocked outlet. Water that appears inside only at the door track, while the field of the balcony stays dry, is the track and the weep, which is closer to the window sealant page than to a slab membrane. Water that stains the ceiling of the room below in a patch under the stack, with the scupper running free, is the penetration. Do not hose the glass and call it a balcony test. Glass and frame leaks are the window page. Interior reseal of a window is S$180 to S$380. That band is not a balcony membrane.

Decking is the other confusion. The balcony decking and drain-cleaning page is a clean of an existing deck and its outlets. It is not a hack of the slab and not a new membrane. If the timber or composite is holding water against the original falls, the deck comes up before anyone can see the scupper. Quote the clean on its own page. Quote the membrane, if the slab itself is the failure, on inspection. Mixing them into one “balcony package” is how a blocked outlet gets a torch-on price.

Condo balconies add the managing agent. The tile you stand on may be yours. The railing, the external face and sometimes the waterproofing of a ledge that is drawn as common property are not a private afternoon job. Write to the MCST before a contractor cuts the edge or drills the kerb. An HDB balcony still has the railing rules: do not drill the railing, and do not enclose the balcony with a screen and call it waterproofing. Awnings that project are a separate approval, including SCDF where the guideline says so, and the polycarbonate awning page is the leak at a sheet roof over a yard, not this slab.

A careful balcony repair starts with the outlet in the open. The scupper is cleared back to daylight, the fall is checked with water, and only then is a membrane discussed. At the stack, the 400mm zone is cleaned to a sound surface, the screed is the pre-packed waterproofing type HDB names, and the upturn goes onto the pipe, not onto the tile beside it. A sloppy job tiles over the scupper “to look neat”, seals the door weep because it dripped once, and paints a coating up to the railing base where the railing fixing has already punctured it. The puncture at a railing bolt is a metal detail. Silicone on the face of the tile will not reach it.

Homey Furnishing Pte. Ltd. (ACRA UEN 202018148K), 27 Mandai Estate, #06-10 Innovation Place, Singapore 729931, invoices permit-exempt leak checks, regrouting, silicone, and making-good after the water has stopped. V On Construction Pte. Ltd. (ACRA UEN 201611708H), on the HDB Directory of Renovation Contractors, invoices an HDB renovation permit when bathroom finishes are hacked or a new membrane is laid under new tiles. A concealed or new water-supply pipe is a PUB licensed plumber. Homey Furnishing is not that plumber and does not publish a waterproofing warranty term.

Curtains, blinds and roller shades are not part of this booking. Fabric window treatments are a different product, and these pages do not quote them.

Separate rain from a hose, and the outlet from the slab, before you accept a membrane price.

1. On a dry day, pour a bucket at the far side of the balcony and watch where it goes. If it ponds at the kerb, the fall or the scupper is first.
2. Lift whatever is sitting on the outlet. A pot, a deck board and a mat are the usual covers.
3. During the next rain, keep the sliding door shut and the track dry at the start. Photograph where the first indoor drop appears.
4. If the drop is on the glass or the mitre of the frame, stop. That is the window sealant page, and weep holes stay open.
5. If the ceiling below the stack is the only stain, ask for the 400mm detail in the quote, not a whole-floor slogan.

The 400mm line is an HDB finishing rule for open balconies when finishes are replaced. Condos follow their drawings. Landed balconies are often roofs of the room below, which is a different structure.

Sliding doors are designed to leak a little into the track and then out. A bead that closes the weep holds that water until it finds the interior screed. The window pages on this site already refuse that bead. A balcony contractor who “stops the drip” by sealing the only exit is making the bedroom leak he was hired to end. If the track is full of grit, the published window clean is S$60 to S$100. That is a clean, not a membrane, and it is the right first spend when the photo shows sludge rather than a failed slab.

Interior silicone on the room side of the frame, S$180 to S$380 a window on the window-repair page, is a seal from inside. It does not replace a stay, a rivet or the balcony membrane. Keep the invoices apart so a frame drip is not billed as a 400mm stack detail.

The balcony does not get a published membrane price. The small bands below are other pages, listed so they are not stretched to cover a slab.

If the quote does not name the outlet, it is not a balcony quote.

1. Is the price for the 400mm stack zone, the scupper, or the whole slab?
2. Will the scupper still see daylight when the tile goes back?
3. What happens to the door-track weep?
4. Is any of this the published decking clean, or is it all quote on inspection?
5. For a condo, has the MCST agreed the edge is yours?
6. Will you pond or rain-test after the outlet is clear, before you sell a membrane?

Water running down the outside of the block, staining the flat below on the facade, is often common property. HDB’s ceiling-leak page sends common-property leaks to the town council. A condo sends them to the MCST. Do not abseil and do not ask us to.

If the balcony is over a bedroom and the ceiling is dripping onto a fan or a light, stop using that circuit. The stain repaint, S$150 to S$400, waits until the balcony stops delivering water. Enclosing the balcony, or adding an awning that the guideline sends to a professional engineer and SCDF, is not a waterproofing coat. Read the building-works page before you cover the opening.

How you're charged

A leak or waterproofing job that already has a sentence on HomeySG uses that sentence. Nothing in this table is a fuel surcharge, and the handyman hour is not added on top of a band unless the written scope says so. A membrane, a balcony, a planter, a roof, an epoxy-grout system, or a listening survey with no matching row is quote on inspection.

Who is allowed to do the work

HDB’s renovation pages split a coat of silicone from a hacked bathroom. Replacing toilet wall and floor finishes is not allowed for 3 years from the completion date of the block, because a membrane sits on the screed. After that, a replacement uses pre-packed waterproofing screed, a membrane upturned at least 150mm at walls, kerbs and pipes, a UPVC floor-trap grating with a long collar, and a water test. Fines for unauthorised work are already written on the permit guide as up to S$5,000. Homey Furnishing does not sign the permit invoice.

• Regrout, a silicone zone, hollow-tile injection and a stain repaint after the water has stopped stay on the published rows. They do not replace a membrane.
• Opening the bathroom floor or wall finishes is V On Construction when the flat is HDB and the work needs a permit.
• PUB’s leak leaflet says it is an offence under the Public Utilities Act to engage an unlicensed worker for plumbing work. A concealed or new supply pipe is a licensed plumber. An exposed trap is a different visit.
• External walls of an HDB block are common property. The town council on the S&CC bill is the first report, not a private injector.
• SCDF does not allow hacking of household-shelter walls, floor slabs or ceiling slabs to chase a pipe. The leak is found another way.
• A window-frame leak is the window sealant page. Exterior rivets and stays stay with a BCA approved window contractor.
• Curtains, blinds and roller shades are not quoted here.

Ways to keep the bill smaller

• Photograph the stain, the wet room, and the water meter before anyone hacks. A hack that destroys the evidence is a second problem.
• Run one test at a time. Shower, flush, aircon and rain on the same afternoon make a useless log.
• If the joint is only mouldy silicone, the published zone is S$80 to S$150. That is not a membrane.
• If the ceiling is already dry and the source is fixed, the hairline repaint is S$150 to S$400. Paint on a live leak is how the stain returns.
• Clear the scupper and photograph the next rain before you approve a membrane. A free outlet ends a lot of “waterproofing” jobs.

WhatsApp the photos to +65 8561 0630.

There is no published balcony-membrane band. Do not borrow the bathroom hack price of S$4,000 to S$7,000 for an open balcony. That sentence is a bathroom.

Anything not in that table is quote on inspection.

WhatsApp the photos to +65 8561 0630. The reply uses a band already printed on HomeySG, or it says quote on inspection.

Official pages, not a legal opinion

The 400mm radius and the 150mm upturn are copied from HDB’s building-works guideline for open balconies and kitchens. They are not a condo by-law and not a landed-roof specification.

• HDB building works. Open balcony: pre-packed waterproofing screed, membrane only around the stack for 400mm, upturn 150mm.
• HDB ceiling leaks. Common-property water is the town council.
• HDB renovation information. Bathroom finish rules are not the balcony paragraph. Do not mix them.
• SCDF shelter works. A balcony repair is not a licence to hack a household shelter wall behind it.

• Decking and drain cleaning
• If it is the frame
• Awning and gutter leaks
• Bathroom membranes
• Handyman price list