Shower and Bathtub Plumbing

Pan and liner leaks

This is the failure that does serious, expensive damage, and it is almost always slow.

A tiled shower floor is waterproofed by a pan or liner underneath, traditionally a sheet membrane in a mortar bed, now often a sheet or liquid membrane over a preformed base. The tile and grout are not the waterproofing. They never were. When the membrane fails, or was never installed correctly, water passes through the grout, through the bed, and into the framing and subfloor.

Signs: a musty smell in the bathroom, discoloured or springy flooring outside the shower door, a stain on a ceiling below, loose tiles at the base, efflorescence at the bottom row of grout, and a shower that seems to need more grout repair than makes sense.

The unwelcome truth is that a failed pan cannot be repaired from above. Regrouting, sealing and coatings applied over a failed membrane hide the symptom while the framing keeps getting wet. Anyone offering to fix a leaking shower pan with sealant is selling time, not a repair.

What we do is establish whether the pan is actually the source, a flood test on the plugged drain, held for 24 hours with monitoring below, is definitive, and then set out the real options: a full tear-out and rebuild with a properly detailed membrane and drain, or a conversion to a preformed base with a factory-integrated drain, which is often cheaper and more reliable than rebuilding a traditional mortar bed.

The drain connection itself is a frequent culprit and a happier finding: a clamping drain whose ring has loosened, or a membrane not properly clamped to it, leaks at exactly the point where all the water goes and is sometimes accessible from below.

Diagnosing a leak without demolition

Before anything comes apart, we isolate the source, because the repairs are wildly different in cost.

Run the shower with the drain blocked and watch below. Water then means pan or drain, not supply.

Fill the tub and let it stand, then drain it. A leak on standing means the overflow gasket or the pan; a leak only on draining means the trap or waste connection.

Pressurise with no water running. A leak with everything off is a supply pipe or a valve body, and that is behind the wall.

Wet the walls only, not the floor. Isolates a wall or surround failure from a floor failure.

Moisture meter and thermal imaging to map the wet area, which frequently shows the water is travelling from somewhere other than the obvious point.

We report what the tests show, including when the answer is that tile has to come off. Guessing wrong on a shower leak is how people pay twice.

Tub-to-shower conversions

A common request, particularly for ageing in place, and the plumbing side is more involved than the demolition suggests.

The drain has to move, a tub drain sits at one end, a shower drain sits centrally, which means opening the floor and reworking the trap and waste, and the fall available under the floor decides what is possible. On a slab, this is a significantly bigger job than on a crawl space or basement.

The valve usually gets replaced, because a tub-shower valve has a diverter that a shower does not need, and because it is the sensible moment to fit pressure-balancing or thermostatic protection.

Waterproofing gets done properly from the start, which is the whole point of doing it as a project rather than a swap.

For accessibility, a low-threshold or curbless entry needs the drain and the floor structure planned together, and it is worth deciding early because it constrains everything else. A linear drain at the wall is often the answer, and a bench, a hand shower on a slide bar and blocking in the wall for future grab bars are cheap to include now and expensive to add later.