Waterproofing a home: how to do bathrooms, balconies and rooftops correctly

A summary from technical documents of a material supplier; not a state standard. Real specifications follow the instructions of the product you use. Updated 24 October 2026.

Leaks in bathrooms, balconies and rooftops are costly to fix because tiles must be broken up and relaid, and they often affect the unit below too. The main principle: waterproof before tiling, water-test before acceptance.

1. Common leak points

According to Enic's bathroom waterproofing guide, common leak points include:

Location	Why it leaks easily
Bathroom floor	where the most water collects; water seeps through tile gaps, mortar joints and the floor drain
Around drain pipes	the joint between the pipe and the floor or wall leaks easily
Wall base	water rises up the wall, causing paint to peel and damp and mould
Walls, ceiling	water from the floor above seeps down

Balconies, loggias and rooftops also face direct sun and rain and thermal expansion, so even small cracks become water paths.

2. Reference procedure

Enic's documents describe three common methods:

• Cement-based waterproof coating (e.g. Sika), 4 steps: surface preparation, mixing, applying layer by layer, curing and inspection. The coating is brushed up the wall base by about 20–40 cm.
• Torch-on membrane, 6 steps: surface preparation, measuring and cutting the membrane, primer, torching and bonding, sealing and reinforcing, protective inspection. The membrane is carried up the wall base by about 20–25 cm, with extra membrane reinforcing the pipe collars.
• Self-adhesive membrane, 4 steps: surface preparation, positioning and cutting the membrane, applying the membrane, protective inspection.

What they share: the surface must be clean, flat and dry, pipe collars and wall corners are treated first, enough layers are applied, and only then is the floor tiled. Which type suits your home is for the contractor and supplier to advise based on each situation.

3. Water test before tiling

Enic describes a test step: pond water directly on the waterproofed surface for at least 24 hours (for the Sika coating and torch-on membrane methods). A common way to do it:

1. Seal the floor drains.
2. Flood the floor with water, keeping the water level even.
3. Note the start time and mark the water level.
4. After 24 hours, check the water level, the wall base and the ceiling of the unit below.
5. Tile only when there is no leak.

This is the most important acceptance step for waterproofing; skip it and a small defect may show up after a few months. Some suppliers recommend a longer time; follow the instructions of the material you use.

4. Balconies and rooftops

• The floor must have a slope toward the drain, so water does not pond.
• Waterproof up the walls, around the base of the railing and around the balcony door.
• The protective screed and floor tiles need to be anti-slip and tolerate expansion from sun and rain.
• After tiling, check the drain and drain pipe; clean regularly to prevent blockage.

5. For apartments

• If the leak comes from pipes or common-owned parts, you must work with the management board and the developer; luatvietnam cites Circular 05/2024/TT-BXD on coordinating so the maintenance team can handle leaks involving common-owned parts.
• If work inside your unit damages common parts or affects another unit, you must restore and compensate (same source).
• If you want to break up the floor, replace pipes or move the bathroom: see renovating and repairing an apartment.

6. Checklist when taking over an apartment

1. Ask the developer whether the unit's bathroom and balcony floors have been waterproofed, with what, and for how long it is under warranty.
2. Ask for a water test if possible, or see the waterproofing acceptance record.
3. Check the ceilings and wall bases of rooms next to the bathroom and balcony: stains, peeling paint, mould.
4. Check the floor slope and drain: pour a little water and see whether it flows to the drain.
5. Record defects in the handover record (taking over the home).

7. Checklist when finishing the home yourself

1. Write waterproofing as a separate item in the construction contract, with the material type and number of layers.
2. Require a 24-hour water test with photos and a signed confirmation before tiling.
3. Tile only after the protective layer has dried.
4. Keep the record and photos as the basis for warranty claims.
5. Also choose flooring suited to each area (choosing floor materials).

Note: this article gives no waterproofing unit prices because no reliable source was accessible; ask for a quote with clear quantities and a written warranty.

• Enic — Bathroom waterproofing guide (3 methods, 24-hour water test, common leak points, wall base 20–40 cm / 20–25 cm; a material supplier, page shows no publication date), accessed 24 October 2026.
• LuatVietnam — Do you need permission to repair an apartment? (mentions Circular 05/2024/TT-BXD on floor and bathroom leaks involving common-owned parts; no publication date found), accessed 24 October 2026. Check against the original document.