Wet rooms in Glasgow tenement flats
Glasgow's tenement stock puts a timber floor, a shared soil stack and a neighbour's ceiling between your shower and a very expensive problem. Here is how a tenement wet room is done properly.
What is different about a tenement wet room?
A tenement wet room sits on suspended timber joists above another household, so the floor must be stiffened, the drain must fit a shallow build-up, the waste must reach the existing soil stack at a workable gradient, and the entire floor must be tanked and flood-tested — not just the shower zone.
What decides whether the job is straightforward
Every tenement survey answers the same four questions before we can price the work.
- 1
Joist depth and direction
Joist depth sets how much build-up is available for the former and drain. Direction sets where a linear drain can run without notching across the span.
- 2
Distance to the soil stack
The waste needs a continuous fall to the stack. The further the run, the more depth it consumes, which competes with the depth needed for the falls.
- 3
Access to the ceiling below
Some connections are far simpler with access from the flat underneath. Where that is not available, the design works within the floor void from above.
- 4
Condition of the existing floor
Pre-1919 decking is rarely suitable for tiling. We usually replace it with a rigid tile backer board fixed to the joists to eliminate flex.
How we build into a timber floor
The shower zone is formed with a purpose-made recessed former set between the joists, rather than by cutting a slope into the structure. The former arrives with the fall already built in, which removes the biggest source of error on site and keeps the notching within acceptable limits.
Around the former, the deck is replaced with a rigid board bedded and screwed at close centres so the floor cannot deflect. Deflection, not water pressure, is what cracks a tiled wet room floor. Once the deck is solid, the primer, reinforcing tape and bonded membrane are applied across the full floor and up the walls.
Flood testing
On tenement jobs we flood-test the tanked floor before tiling. The drain is temporarily blocked, water is held on the membrane, and the level is checked over time. Finding a pinhole at that stage costs an hour; finding it after the neighbour's ceiling stains costs a great deal more.
Protecting the flat below
We ask you to let the downstairs neighbour know the dates. It is a courtesy that has practical value — if anything appears on their ceiling during or after the work, we want to hear about it immediately rather than months later. See the tanking specification we work to.
Deeds, factors and building standards
- Check your title deeds before any work touching the soil stack or common drainage — these are usually shared elements.
- Where a factor manages the building, inform them of the work and the dates in writing.
- The Tenements (Scotland) Act 2004 governs shared maintenance and access where deeds are silent.
- Like-for-like replacement of sanitary fittings is generally exempt work under Scottish building standards.
- A building warrant is required for structural alterations, new drainage arrangements or forming a bathroom in a room not previously used as one.
- Confirm any warrant question with Glasgow City Council Building Standards before work begins — the responsibility sits with the property owner.