Bathrooms fail at ventilation and storage long before they fail at tiles

Treat the sections below as a sequence. With bathrooms, getting the early decisions right makes the later ones much easier.

The fan has to keep running

A shower releases most of its moisture into the air over the following twenty minutes, by which time the fan on a light switch has usually stopped. An overrun timer, a humidity-sensing fan, or simply leaving the fan switched on is what actually clears it. Fans also need somewhere for replacement air to come from, which is why a fan in a sealed room with a tight door moves far less air than its rating suggests.

Undercutting the door by around ten millimetres is the standard cheap solution and it makes a measurable difference.

Two kinds of storage, two kinds of space

Daily items need to be within arm's reach of where they are used, wet-handed, in about a second. Bulk — spare towels, cleaning products, packs of things — needs volume and can be anywhere, including outside the bathroom entirely. Confusing the two produces the common result of a beautiful mirrored cabinet stuffed with toilet rolls and a shelf of shampoo on the bath edge.

A niche in the shower wall, formed at construction, is the only storage that is genuinely in the right place and it costs almost nothing to include.

Waterproofing is a system, not a product

Tiles and grout are not waterproof; the tanking membrane or board behind them is, and water that gets past the grout is meant to be stopped there. This is why a shower leaking into the room below is usually a failure at a junction or a pipe penetration rather than across the field of tiles.

Junctions between different materials, around trays and at internal corners are the points that move and therefore the points that fail. Any suspicion of water reaching structure or wiring is a job for a qualified installer, not for more sealant over the top.

Layout is dictated by the soil pipe

The toilet has the least flexibility because waste needs a fall of roughly one in forty and a short run to the stack. Basins and showers can move much further because their pipes are smaller and pumps are available, though pumped waste adds noise and a failure point. This is why bathroom plans that look arbitrary are often the only arrangement the drainage allowed.

Establishing where the stack is before drawing anything saves redesigning a scheme that was never buildable.

Small decisions that age well

An access panel to the bath trap and to any concealed valve turns a future emergency into a twenty-minute job. Slip resistance matters most where water lands, and a rating is worth checking for a floor rather than assuming a matt finish is enough. Wall-hung sanitaryware makes floor cleaning genuinely easier and requires a supporting frame that has to be planned in advance.

The quieter point is that extraction, access and drainage are the three things that cannot be added later without demolition.

What photographs well and what lives well are frequently different rooms.

Heat and surfaces

A bathroom warms up quickly and loses heat quickly, which is why a heated towel rail alone is often not enough as the only heat source in winter. Warm surfaces attract less condensation than cold ones, so an insulated external wall does more for mould than a stronger fan in some rooms.

The quieter point is that mirrors fog because they are colder than the air; a demisting pad or simply a mirror on an internal wall reduces it. Persistent black mould after these measures suggests a fabric problem and is worth having assessed by a professional rather than repeatedly cleaned.

The takeaway

Get the extraction, the access panels and the reachable storage right. The tiles are the easy part.

A room that is used will always beat a room that is finished.