Bathrooms in Hong Kong are often compact, and the city’s humid climate makes careful renovation planning especially important. Focusing only on tiles, fittings and visual style—while overlooking drainage, waterproofing and the boundary of the shower area—can lead to standing water, mould, blackened silicone seals and, in more serious cases, leaks affecting the flat below. A practical bathroom should first ensure water flows reliably towards the drain, then address waterproofing, shower screens and storage. Here are five frequently asked questions to guide the process.
1. Does a small bathroom need wet–dry separation?
Not every bathroom requires a fully enclosed shower cubicle, but the shower area should be clearly separated from the toilet and basin zone wherever possible. In a compact bathroom, this may be achieved with a fixed glass panel, a short shower screen, a shower curtain with a water stop, or a subtle change in floor level combined with a clear drainage direction.
The success of wet–dry separation is not determined by the number of glass panels, but by whether water can be directed efficiently towards the floor drain. If the drain sits in the dry zone, or the shower area has no defined fall, water may still escape through gaps even with a shower screen in place. Confirm the shower position, drain location and relationship to the toilet and basin before choosing a solution that suits the available footprint and daily routine. A glass screen, low water stop or floor-level transition can all form part of an effective wet–dry separation strategy.
2. How much drainage fall should a bathroom floor have?
The bathroom floor should slope gently from higher points towards the drain. A practical reference is a fall of around 1 to 2 per cent, or approximately 10 to 20 mm per metre. Too little fall allows water to remain around tile joints, screen edges and corners; too much can make the floor uncomfortable to stand on and complicate tile laying and finishing details.
Place the drain within the shower zone and as close as practical to the primary water source, reducing the distance that water must travel. Before tiling begins, ask the contractor to carry out a water-flow test once the levelling screed is complete. This confirms that water moves naturally to the drain and does not flow back beyond the shower screen. Hong Kong’s Buildings Department also advises locating floor drains appropriately to minimise fall distance and support future inspection and maintenance.
3. How far should waterproofing extend?
Waterproofing is one of the hidden parts of a bathroom renovation where cost-cutting should be avoided. A typical approach is to waterproof the entire floor, return the waterproofing up dry-zone walls by at least around 300 mm, and extend it to at least 1,800 mm high around shower walls. Where the budget and site conditions allow, carrying the waterproofing up to the ceiling offers added protection. Floor-to-wall junctions, internal corners, drain openings and pipe penetrations should receive additional attention, as these are common leakage-risk points.
Before tiles are installed, a flood test should be carried out: the drain is sealed, water is retained on the floor, and the area is monitored for at least 48 hours. Check both for unexplained changes in water level and for signs of moisture on the ceiling below or neighbouring walls. Waterproofing products, coating thicknesses and curing periods should always follow the selected system’s installation requirements; applying an extra coat cannot replace proper substrate preparation, repairs and testing.
4. Should you choose a fixed, sliding or hinged shower screen?
The right shower screen depends on the bathroom’s dimensions, fixture layout and available door-swing space. A fixed inline glass panel is the most space-efficient and relatively easy to clean, making it suitable for shorter shower areas or bathrooms that do not require full enclosure. Its water-containment performance, however, depends on the panel length and shower-head direction. A fully enclosed shower area contains water more effectively but needs enough room for a hinged or sliding door.
With a hinged screen, ensure the door cannot strike the toilet, basin or vanity. In tighter spaces, sliding or inward-opening doors may work better, although their tracks, hardware and seals should remain accessible for cleaning and maintenance. Choose safety toughened glass, include appropriate water stops along the bottom, wall edge and door gap, and test the joints with a shower once the silicone has fully cured.
5. How should you inspect drainage and waterproofing?
After completion, do not assess the bathroom solely by whether the tiles look level and neatly finished. Turn on the shower, basin and toilet one by one, observing drainage speed, areas of standing water and whether water stays within the wet zone. Pour a bucket of water across the shower area to confirm it collects at the floor drain rather than pooling at the screen threshold, doorway or corners.
Also inspect whether the shower-screen silicone is continuous, whether there are cracks along wall-to-floor junctions, and whether plumbing connections beneath the vanity show any signs of leaking. Run the exhaust fan to ensure moist air is being extracted. Keep records of flood tests, photographs of concealed works, drainage-pipe locations and material specifications. These will provide a useful reference if repairs are needed or if discussions arise with building management or the contractor.
The key to a successful bathroom renovation is to prioritise what cannot be seen before the finishes that can. When drainage falls, waterproofing and shower-screen placement are coordinated before construction begins, even a compact bathroom can be drier, easier to clean and more durable over time.
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