Spray Foam Removal Explained

Spray foam is applied as a liquid that expands and sets against the underside of the roof. It comes in two forms. Open-cell is soft and spongy and is usually sprayed in a thicker layer. Closed-cell is rigid and dense and sets hard. Both bond to whatever they touch, which in most lofts means the roofing underlay and the sides of the rafters.

That bond is the root of the problem. A traditional UK roof is built to breathe. Air moves through the loft, usually in at the eaves and out at the ridge, and carries moisture away before it can sit on the timber. Foam fills that space and seals the underside of the covering, so moisture that would have dried out stays in contact with the felt and the rafters instead. How much damage that causes depends on the roof, how well it was ventilated to begin with, which foam was used and how thickly it was applied. Some roofs are still sound years later. Others show perished felt, damp timber or mould within a few seasons.

The second problem is that nobody can see the roof

Even where the timber is fine, the foam hides it. A surveyor cannot check the battens, the underlay or the condition of the rafters, and what cannot be inspected tends to be treated as an unknown. That is what turns a loft job into a mortgage or sale problem, and it is why a lot of removals happen on roofs that were not actually failing.

How removal works

Removal is mechanical. The foam is cut and scraped off the rafters and the felt by hand. It is dusty, slow work measured in days rather than hours, and closed-cell takes considerably longer than open-cell because it is rigid and more strongly bonded. Where the underlay has already perished, or the foam cannot be taken off without destroying what is left of it, the covering is lifted from outside instead and the roof is re-felted, re-battened and re-laid. That is the difference between a job that is purely a removal and one that becomes a re-roof, and it is the main reason nobody can give you a sensible price without looking first.

When you are choosing who does it, the things worth insisting on are simple: a survey before a price, a written scope that says what is being removed and what happens to the roof afterwards, photographs of the work, and a contractor who can carry out the roofing if the covering turns out to need it.