How to waterproof a terrace without lifting the floor

If you have damp patches on the ceiling of the flat below, the first thing many people will tell you is that the whole terrace floor has to come up. That is not always true.

Waterproofing membranes such as ECODRY and DRY are laid directly over the existing floor. You save yourself the demolition, the rubble, the skip and the weeks of work. On top of the membrane you fix the new stoneware or porcelain tile and the terrace is back in use.

When can it go on top and when can it not?

It can be laid over the current floor if that floor is sound and well bonded. If there are loose or hollow tiles, those do have to be chipped out and filled. And the substrate has to be dry: maximum residual moisture is 3% for the 0.8 mm membranes and 5% for the 1.25 mm ones.

Which membrane to choose

• ECODRY80 / DRY80 (0.8 mm) — the usual choice for a domestic terrace. Light and easy to handle.
• ECODRY120 / DRY120 (1.25 mm) — when the surface is large, use is heavy or there are cracks in the substrate: it bridges cracks of up to 3.6 mm.

Both are sold by the full roll of 5, 10, 20 or 30 metres.

The four steps

1. Prepare the substrate. Clean it, check that it is sound and dry, and make good any loose pieces.
2. Lay the membrane. It is bonded with tile adhesive. The 0.8 mm membranes overlap by 10 cm; the 1.25 mm ones go butt joints and are sealed with tape.
3. Sort out the detail points. This is where jobs go wrong: corners, wall junctions, drains, scuppers and pipe penetrations. Each one has its own preformed piece.
4. Tile on top. With C2 tile adhesive and whatever movement joints are required.

See it on site

Installing DRY120 and ECODRY120 on a terrace:

Installing DRY80 and ECODRY80:

On large surfaces two people work together, which speeds up laying considerably:

And this is what a real finished job looks like, from a drone:

What people usually forget to order

The membrane on its own is not enough. You will need SEALPLUS adhesive, tape for the joints, preformed corners and the right piece for each drain. It is the part that ruins the most jobs and the cheapest one to get right.

Do I need to be a professional?

No. No certificate or special machinery is needed. If this is your first time, call us before ordering: in five minutes we work out the metres and tell you exactly which pieces you need.

See all membranes for terraces and roofs · Call us on 951 207 299