Hollow and tenting tiles, fixed through the grout line

Hollow HDB and condo floor tiles can be re-bonded by injecting low-viscosity epoxy or PU through 2mm grout-line ports. Four to ten intact tiles are S$350 to S$750 and about three hours. Tented tiles that must be lifted are S$550 to S$1,200. The screed stays, so the HDB 3-year BTO bathroom restriction on hacking is not triggered.

A dull tap means the adhesive has let go and the tile is bridging a void. In an HDB the void is often in the screed-to-tile bond, not in the structural slab. A BTO bathroom is frequently a prefabricated bathroom unit, a PBU, with a thinner build-up than a 30-year resale screed. Thermal movement still pops the bond, but the repair logic is the same if the tile is flat and intact: fill the void from the grout line. A 2mm port goes through the grout, not the glaze. Low-viscosity epoxy or PU is fed until it shows at the next joint. The port is then grouted. Screed thickness does not change.

That is why the job is not hacking and why it stays available in the first three years of a BTO, when HDB does not allow bathroom tiles to be hacked. The one-year defects liability period is a separate clock. A hollow tile reported inside DLP should be raised with the developer first. After DLP, and during the three-year hacking restriction, injection is the method that does not remove the tile. Tenting is different. The field has expanded into a ridge. Those tiles are lifted, cleaned and re-bedded. Injection will not pull a tented tile flat.

Epoxy and PU are not interchangeable. Low-viscosity epoxy is the usual fill for a dry void under a flat tile. PU foam is used when a little movement or a damp edge needs a more flexible fill, and it is the wrong choice when you need a hard bond you can trust under a point load. Neither product is a waterproof membrane. If the ceiling below is stained, or the PUB meter spins with every tap closed, the void is a symptom and filling it hides the leak.

Homey Furnishing Pte. Ltd. (ACRA UEN 202018148K), 27 Mandai Estate, #06-10 Innovation Place, Singapore 729931, carries the permit-exempt portion of this work. V On Construction Pte. Ltd. (ACRA UEN 201611708H), listed on the HDB Directory of Renovation Contractors, carries any scope that needs an HDB renovation permit. Those two invoices are not interchangeable. Hacking bathroom tiles in a BTO under three years old is the restricted work. Injection leaves the tile and the screed. A failed membrane is waterproofing, which is permit territory when the build-up is opened.

Spend ten minutes with a torch, your phone camera, and a tape before you buy a product or book a hack. Write down what you see. The safe checks below do not ask you to open a live wire, cut a pressurised pipe, or lean out of a window. Tap with a coin or a screwdriver handle in a grid and mark hollow sounds with painter tape. Try to slide a card under the edge. Measure any ridge with a straightedge. Photograph the pattern.

Stop at the red-flag column. Stop if the tile is cracked through, if a card slides under it, if the ceiling below is wet, or if you are about to drill the glaze. The reason DIY fails is almost never a lack of effort. It is that the tool or chemical makes the next professional repair harder, or it hides a leak, a live conductor, or a deposit line until the damage is larger than S$350 to S$1,200.

This is the sequence a careful technician uses so you can tell a shortcut from a finished job. Tools stay in the van. Readings and photos go on the same worksheet as the price. The kit is a 2mm bit used only in the grout, a low-viscosity epoxy or PU injection gun, tape, and matching grout. The glaze is not the port.

1. Step 1. Make the area safe and confirm the symptom still matches the photos. For Hollow and tenting tiles, fixed through the grout line, that means Stop if the tile is cracked through, if a card slides under it, if the ceiling below is wet, or if you are about to drill the glaze.
2. Step 2. Measure before touching the finished surface. Tap with a coin or a screwdriver handle in a grid and mark hollow sounds with painter tape. Try to slide a card under the edge. Measure any ridge with a straightedge. Photograph the pattern.
3. Step 3. Set protection and lay out the tools that belong to this material. The kit is a 2mm bit used only in the grout, a low-viscosity epoxy or PU injection gun, tape, and matching grout. The glaze is not the port.
4. Step 4. Carry out the repair in the order the material allows. a void is filled while a leak is still feeding it, or a tented tile is pumped and left proud is the failure this order is written to avoid.
5. Step 5. Test in place. The field is tapped again. Ports are grouted. A straightedge does not show a new ridge. The household is told which tiles were injected and which were left because they were tented.
6. Step 6. Clean, label the photographs against the invoice lines, and leave the statutory openings, weep holes, access panels and labels visible.

The order matters because a void is filled while a leak is still feeding it, or a tented tile is pumped and left proud is what happens when a step is rushed. Handover is a measurement, not a handshake. The field is tapped again. Ports are grouted. A straightedge does not show a new ridge. The household is told which tiles were injected and which were left because they were tented. If the reading or the water test fails, the visit is not closed and a second line is priced before anyone leaves. Permit work, if the diagnosis has moved into hacking, waterproofing, or a new layout, stops here and is repriced through V On Construction Pte. Ltd. UEN 201611708H.

Injection is the three-hour repair. Re-bedding is the half-day repair. A full bathroom hack is a permit project and a different contractor line. Prices below are 2026 Singapore bands for the described scope. They are not a coupon and they are not a guess after an unopened door. A second trade, such as a PUB licensed plumber or an EMA licensed electrician, is named when the law requires it rather than buried inside the labour line. Compare rows by what they include. The planning-life column belongs to that row only.

2026 SGD scope bands

Brand, material and lifespan

A matching spare tile matters only when the tile is cracked. Hollow but intact tiles stay. Do not buy a box of new tiles for an injection.

Three worked jobs show how the same symptom is priced differently in a new BTO, an older resale flat, and a private condo or landed house. The totals are the lines a household actually paid, not a national average. Permit-exempt invoices are issued by Homey Furnishing Pte. Ltd. UEN 202018148K.

Case 1: 4-room BTO in Tengah, year two

The living-room field sounded hollow in eight tiles. All were flat. Epoxy injection through the grout was S$640 and three hours. The bathroom was not touched, so the three-year hacking restriction never came up. The developer DLP had already ended.

Case 2: 28-year resale in Toa Payoh

A corridor had twelve hollow tiles and three that had tented. Injection of the flat ones was S$580. Lifting and re-bedding the three tented tiles was S$420 on the same visit. Total S$1,000. The screed was sound. No membrane was opened.

Case 3: Condo in Katong

The bedroom sounded hollow and the ceiling of the unit below was stained. Injection was refused. The leak was traced to a failed bathroom membrane next door to the bedroom slab edge, and the owner was pointed at waterproofing rather than a S$500 fill that would have hidden it. The visit fee for the diagnosis was S$120.

Book injection or re-bedding on the tile repair page. If the ceiling below is wet, start with the leak, not the grout. Send the photos and the measurements from the ten-minute check. The reply prices the band on this page against what the photos actually show.

• Book tile injection or re-bedding
• Waterproofing
• When HDB needs a permit
• Permit versus no-permit matrix