Tanking a Maltese bathroom before you tile

Nobody is going to make you do this

If you have renovated a bathroom in the UK, you may be carrying an assumption that somebody, somewhere, checks the waterproofing. Drop that assumption. Among the published Maltese sources used for this article, there is no building-code line that forces a contractor to tank a bathroom before tiling, and none that stops them tiling straight onto screed. The consequence is procedural rather than dramatic: tanking is a line item you specify, or it is not in the job.

A tiling quote is a quote for tiling. Tiler.mt's calculator, like the turnkeymalta.com model behind it, prices per square metre of tiled surface — and in Malta that surface is usually large, because floor-to-ceiling tiling in bathrooms is the norm here rather than the half-height British compromise. But square metres of tile and square metres of membrane are two different purchases, applied by two different trades on two different days, and one of them has a 24–48 hour pause in the middle of it.

The sequence

Maltese contractors work a wet room in roughly this order. WP Ltd's stated process starts earlier still: a survey before the quote, which on a bathroom means someone looking at the existing substrate, the drain positions and the state of the walls before any number is written down.

1. Strip-out. Sanitaryware, old tiles, old screed where it is drummy or contaminated, back to the slab. Maltese floors are concrete slab and screed, not joists and deck, so there is no plywood decision to make — but there is a lot of weight to carry down, and in an apartment that route is the common parts.
2. Substrate and screed. The screed sets the falls towards the drain. This is the stage where a waterproofing additive can be batched into the mix; Kibitec prices additive at €5–10/bag.
3. The membrane. Either liquid-applied or sheet, over floor and up walls to the wetted height. Lazarus Turnkey specifies cementitious slurry for wet areas. WP Ltd deals in liquid membrane types with differing lifespans, which is a question worth asking of any applicator: not just which membrane, but how long the manufacturer stands behind it.
4. Corners, junctions and the drain. Reinforcement tape or preformed pieces at wall-to-floor and wall-to-wall corners, and a properly dressed collar where the membrane meets the gully. This is where leaks happen. It is also where a cheap price shows up later.
5. The flood test. Plug the drain, fill, hold for 24–48 hours, inspect the ceiling below. Lazarus Turnkey's rule is blunt and worth adopting verbatim: never tile over untested waterproofing.
6. Tile. Only now does the tiler's per-m² rate start earning.

If the job is in Gozo, add the obvious: every bag, bucket and roll crosses on the ferry, so the membrane needs to be on site before the screed is finished, not ordered when the screeder packs up.

What the layer costs

These are the rates published by Kibitec Ltd, reproduced as given:

Note the units. The membranes are per square metre of surface treated — and in a floor-to-ceiling Maltese bathroom the tanked area is considerably more than the floor plan. The additive is per bag, which is why it is not a substitute for the membrane and should not be presented as one in a quote. If a quote shows "waterproofing" against a bag price, you are buying a screed property, not a tanked wet area.

For the whole job, Turnkey.mt publishes whole-bathroom bands of €3,600–9,600 including waterproofing. Read that as the envelope a specified, tanked, tested bathroom lands in — strip-out, screed, membrane, tiling, sanitaryware — rather than a tiling-only figure.

The flat below, and Cap. 398

This is the part that changes how seriously you take step five. Malta's housing stock is overwhelmingly apartments, and a bathroom in an apartment sits above somebody's ceiling.

GTG Legal's account of condominium maintenance is that Article 12 apportions cost half and half between the parties concerned — unless negligence is shown. So a leak from your shower into the flat below does not arrive as a plumbing problem. It arrives as an apportionment argument, in which the other side has an obvious incentive to demonstrate negligence and you have an obvious incentive to demonstrate the opposite.

What demonstrates the opposite is documentation, created at the time and not afterwards:

• the specification naming the membrane system and the treated area;
• dated photographs of the membrane before tiling, including corners and the drain collar;
• a record of the flood test — when it was filled, how long it was held, who inspected the ceiling below and what they found.

That last item costs nothing and is the single most useful piece of paper in a dispute, because it is the evidence that the pause was taken rather than skipped to keep the tiler on programme.

Writing it into the quote

Four lines to insist on, in this order:

• Area. Square metres of membrane, stated separately from square metres of tile, with the wall height it goes up to.
• System. The named product or system type, and whether it is liquid or sheet — the rates differ, €15–25/m² against €20–35/m² installed.
• Detailing. Corners, wall-floor junctions and the drain collar treated as part of the system, not as an extra.
• Test. A flood test of 24–48 hours, with tiling starting after it, and the result recorded.

A tiler who is CheckYourTraders-verified is verified as a tiler. The membrane is a separate decision you are making on your own authority, before anyone opens a box of tiles — and, on the evidence of these sources, nobody in the Maltese regulatory chain is going to make it for you.