Garage roof waterproofing in London

Why garage roofs are usually the first to leak

A garage roof leads a hard life with little maintenance. It is almost always flat or close to flat, so water drains slowly and tends to sit in low spots. The original covering is often a single layer of felt laid years ago, which goes brittle, blisters and splits as it ages. And because nothing inside the garage seems urgent, the roof is usually left until water is already coming through. By the time a garage roof is noticed, the covering has normally failed across the whole surface rather than in one spot, which is why patching it rarely holds for long.

Sealing a garage roof, or replacing it

A garage is a small, simple structure, which works in your favour. If the roof structure beneath the covering is sound and only the surface has worn out, the roof does not need rebuilding: it is cleaned, prepared and sealed over with a liquid-applied system, and the garage stays exactly as it is. A full tear-off and rebuild is only necessary where the structure itself, the deck or the joists, has rotted or failed. An Approved Contractor will look at the roof and tell you honestly which of the two situations you are in, rather than defaulting to the more expensive one. Where the structure is sound, sealing the roof is markedly cheaper and quicker than replacing it.

One check to make on an older garage

There is one thing worth knowing before any work. Many older garages, particularly detached ones built decades ago, have roofs made of corrugated cement sheet, and sheet of that age can contain asbestos. A roof like that needs to be assessed by an asbestos specialist before anything is done to it, and that is specialist work in its own right. The liquid-applied system here is for the common garage roof types that are safe to overlay: flat felt, concrete and metal. If you are not sure what your garage roof is made of, an Approved Contractor can tell you, and point you to the right specialist if a cement-sheet roof needs checking first.

What the work involves

Because a garage roof is small, the work is quick. The roof is cleaned and prepared, any local defects are made good, a primer suited to the surface is applied, and then the liquid waterproofing with mesh reinforcement, worked into the edges, upstands and any details. It cures into one continuous, seamless surface with no laps or joints to fail. The system is cold-applied, with no torches or hot works, and a single garage is usually a matter of a day or two rather than a major job.

The HYDRONYLON system

The system used on these roofs is HYDRONYLON, assessed under European Technical Assessment ETA-23/0735. HYDRONYLON LTD supplies it; the work is carried out by Approved Contractors, trained and certified on the system and working across London. A garage roof sealed by an Approved Contractor carries a 10-year product guarantee on the materials, issued to the contractor who does the work. You can see which roof types the system suits on the applications page and the method step by step on the system page.