Can Tiles Be Saved if Foam Is Stuck to Them?

When foam is sprayed up under a roof, it does not always stop at the felt. Where the felt is missing, torn or has gaps at the laps, the foam expands through to the underside of the tiles, and where it reaches the tile it sets onto the rough back surface. Some roofs have no felt at all, which is common on older buildings, and there the foam goes straight onto the tile. Our answer on foam on old roof felt covers the felted case.

Why does the bond matter?

Because removal is a tug of war between the foam and the tile, and the tile can lose. A strong bond to a thin or tired tile may pull a layer off its surface. Clay tiles can be more brittle than concrete ones, and old clay that has taken in moisture for decades is brittler still.

The first look is from the loft, with a torch. We see how thick the foam is where it meets the tiles, whether it has run over the tile nibs, the small lugs that hook a tile on a batten, and whether any tiles are already cracked behind it. That picture shapes the plan before a single tile is touched.

Where the foam can be cut back from inside, we cut it carefully close to the tile and then scrape and shave the last layer by hand. A tile that is sound and flat afterwards stays where it is, or is lifted, cleaned and refitted.

Can a tile be reused after foam has been taken off?

Yes, if it is still whole, flat and clean at the nibs and edges. A reused tile needs a clear lap with the tile below and a firm seat on its batten. A tile with a lump of foam left on its back will not sit properly, and water can then be driven under it.

Reusing tiles is often the better answer for older roofs, because a weathered tile has a colour and texture that new tiles do not match. Our answer on reusing roof tiles covers how sound tiles are judged. On a roof in a conservation area, keeping the original tiles can also be part of what the planning team expects, so ask Somerset Council's planning team where the house sits in one.

Lifted tiles are stacked by slope in the order they came off, so each goes back where it came from.

Some tiles will not come through. Those that crack when the foam is pulled, shear along the nib or flake on the underside are scrapped. A tile with a fine hairline crack may look fine from the loft and still let in water, so cracked tiles are not put back.

Will replacement tiles match?

For concrete tiles from a known range, usually close. For old clay, less so, because weathering changes the shade. The usual remedy is to put the replacements on the least visible slope and move the best-matching old tiles to the front. Our answer on roof tile profiles shows how to identify yours, since the profile has to match as well as the colour.

Clay and concrete are also not interchangeable for minimum pitch. Marley's published figures show different minimum pitches for different profiles, so a replacement must suit the slope. We check the data sheet for the tile before ordering.

We count as we go, photograph the broken tiles and tell you how many need replacing before the roof is closed up, so the final tally holds no surprises.

A few broken tiles on a sound slope are a small repair. Large numbers of failures tell a different story. Heavy bonding across a whole slope, old brittle tiles and rusted battens together make a case for re-tiling that slope rather than saving it piece by piece, and the photos show which position your roof is in.

Is it cheaper to save the tiles?

Not always. Careful lifting, cleaning and refitting takes time, and when many tiles are failing, that time adds up. Against that, new tiles cost money and may not match. The right choice comes from the survey, and we put both routes to you with photos before the price is written. Our guide on re-tiling one side of a roof covers the option of renewing a single slope.

Send photos of your tiles from outside, and of the underside from the loft if you can. We survey, show you pictures of your own roof, and the written price follows. The main spray foam removal page describes the whole job.