Worried about damp or condensation
Tenants saw winter damp marks: foam bonded to the tiles, and timber up to 19.6% in summer
Liverpool · Recent inspection · Spray Foam Inspection
The house
Rendered semi-detached house, let to tenants, with a half-hip plain-tile roof and a front bay. One part-boarded loft and a small void over the bay; no soffit vents, so no ventilation path.
The foam
Rigid closed-cell foam sprayed in 2017, bonded directly to the tiles, battens and mortar bedding, with no membrane at any point seen. It covers both slopes, the hip and the bay void, with the eaves filled solid.
The paperwork
Only the installer's 30-year warranty document survived: no contract, invoice, product data, product approval or condensation-risk assessment, and no insurance-backed warranty provided. The installer has since been dissolved, leaving no trading company behind the warranty.
Why they called
Tenants reported recurring damp marks on ceilings in winter. The owners wanted to know what sat above them, and the long-term options, including for a future sale or remortgage.
What was measured
- Timber 13.6% to 19.6% on a warm summer's day, several near the top of that range at the eaves, the hip and in the bay void.
- Foam about 2 in to 5–6 in thick, with voids of roughly 3 × 3 in and 4 × 2 in.
- About 45 m² sprayed, about 5.6 m² of it in the bay void, where one unfoamed rafter carried heavier water-marking than its neighbours, descending towards the reported winter marks.
What it means
The readings sit under the roughly 20% level where decay risk starts to climb, but summer is normally when a loft is at its least damp, leaving little headroom for winter. Foam bonded to the tiles with no membrane is the arrangement HSE guidance identifies as of principal concern for trapped moisture, and the marked rafter fits that picture.
What happened next
If a sale or remortgage lies ahead, the report sees removal as the realistic long-term fix, budgeting for cleaning and treating the roof timbers, replacing any the opening-up shows need it, some tile breakage, and a new breathable membrane.
For other homeowners
If foam bonded to your tiles does come out, have the bare roof recorded by someone independent of the removal firm, with photographs and fresh readings. It is the only time anyone will properly see those timbers.
Read the guide: Does spray foam cause condensation or rot roof timbers? What the evidence says · Living with spray foam: should I worry?
The honest limit
One summer visit, seeing behind the foam only through small openings. Most tiles, battens and rafter faces could not be inspected, and the marked rafter's link to the ceiling marks could not be established.