How do you know if your loft has spray foam?

Climbing in is not necessary. Open the hatch, point a torch up at the roof slope and look at the slanting timbers, called rafters. In a traditional loft they are dusty bare timber with felt showing in the gaps between them. If instead you see a smooth or lumpy coating covering the wood and the felt together, the roof has been sprayed.

Colour varies a good deal, depending on the make and on how long the coating has been exposed to the dust of a loft. Foam can be cream, pale yellow or grey with age, and it may resemble bubbled plaster or crumbly sponge. It tends to be deepest where the roof meets the walls. If the coating follows the pitch of the roof rather than lying on the loft floor, that is another clear sign. A coating that you can see right up to the ridge is a stronger sign still. Look too at the gable end and around any chimney breast, where foam is often applied in thicker lumps because the surface is awkward.

Ordinary loft insulation is rolled out as a quilt between and over the ceiling joists, which are the flat timbers that carry the bedroom ceilings. It rests on the floor of the loft, and the roof above stays visible. Rigid boards can also be fitted between rafters, but they are flat panels with visible edges and joins.

Foam is laid directly against the roof slope from beneath, so the loft floor may be bare while the slopes are coated. A quick test is to ask whether you can see the felt and the rafters. If not, it is likely foam. Our answer on spray foam against mineral wool compares the two materials in more detail, and it is worth reading if you are weighing up what to put there next.

There are two types. The open-cell kind stays soft and spongy once set, and a thumbnail pressed into a spare patch leaves a dent. The closed-cell kind is dense and hard, like a shell, and grips whatever it touched. Knowing which you have helps with planning any clearance, because the two behave differently under a scraper.

Do not cut into the foam to find out, and do not poke at it with a screwdriver either. A cut disturbs the evidence a survey needs and may damage felt behind it. Press gently at an edge, or simply describe how it looks and feels beside your photographs. The Energy Saving Trust, in loft advice dated 8 May 2026, says a leaking roof is a much smaller worry beneath the softer, open-cell kind. See our guide to open-cell and closed-cell foam.

If you cannot reach the loft, other signs help. A survey report may mention foam or hint that parts of the roof were hidden from the surveyor. Paperwork from a previous owner, such as an installer's invoice, may point to a foam job. A musty smell in the loft, damp patches on bedroom ceilings or a house that feels stuffy can all hint at trouble under the roof, although they have other causes too.

Houses where foam was fitted often look the same from the street, with no mark on the tiles. If your lender or a buyer has raised the question, they may know more about the installation than you do. Ask them what they have seen, and write the answers down alongside the date of each conversation. A neighbour with a similar house may also know whether foam was offered on your street, though that is a hint, not proof.

Stay on the boards or joists, and never step between them. Photograph the foam from several angles, taking in the eaves, the end by the ridge, and any pipe or cable where the coating stops. Include a view of any staining or daylight you can see. Keep the files dated and in the order you took them. A short note of what you saw, written that evening, adds to the record, and a photograph of the hatch from the landing shows where you were standing.

Send them to us with any survey report. We can usually say from the pictures whether a visit is needed soon. If foam is confirmed, the next questions are whether it needs to come off and what that involves. See our answer on whether it needs removing, or go to the main spray foam removal page.