Buying a house with spray foam
Buying a house where the foam was already removed: eaves open and no work identified
Torbay · Recent inspection · Post-Removal Verification
The house
Semi-detached two-storey house with a gable-ended interlocking tile roof on trussed rafters, lined with felt. With the foam gone and about 250–280 mm of insulation on the loft floor, it is a ventilated cold roof again.
The foam
Sprayed onto the felt and later removed; too little remained to tell open from closed cell. Removed, where inspected, from both slopes, both ends, the apex and the eaves, leaving minor residue in the felt laps and loose crumbs at the eaves.
The paperwork
Removal order, invoice and a ten-year workmanship warranty from the removal contractor. Not supplied: the photos or video of the finished eaves listed on the order, and any document from the original installation.
Why they called
A buyer's solicitor asked about the removal, internal dampness, the timbers, and whether any work was needed.
What was measured
- Loft air 12.5 g/kg against 12.0 g/kg outside: a gap of 0.5 g/kg.
- 13 timber readings, none at or above 20%: highest 19.1%, lowest 11.5%; four upper readings of 18.6 to 19.1% spread across the roof.
- Dew point 17.7 °C, coldest surface 18.7 °C on the north gable blockwork: a 1.0-degree margin on a humid afternoon after rain.
- Eaves 4.3 m each side, where guidance expects a continuous 10 mm gap; daylight through the soffits at four points, other bays clear.
What it means
With the foam gone, this is a cold roof again, which the report treats as relying on ventilation. The test is the gap between the water in the loft air and the air outside: in a well-ventilated loft the two normally stay close. Here it was 0.5 g/kg. The moderate rating comes from the narrow margin at the north gable and four timber readings just under 20%, worth re-checking in winter rather than fixing now.
What happened next
No work to the roof, timbers or ventilation was identified as necessary; clearing the loose crumbs is optional. A winter set of timber readings would show whether the upper timbers stay below 20%.
For other homeowners
Buying where foam has been removed? Ask for the removal order, not just the invoice, and check you have everything it lists, especially photos of the eaves.
Read the guide: Buying a house with spray foam: step by step · Should you buy a house with spray foam insulation?
The honest limit
Only the loft above the main house was inspected; the subfloor and other timbers the solicitor asked about were outside scope. Tiles were seen from the ground, on one humid afternoon.