Told to remove it, or holding a removal quote
Quoted for a new roof: the wettest timber sat round a chimney the bathroom fan vents into
Chester · Recent inspection · Spray Foam Inspection
The house
Mid-terrace slate-roofed house from the 1920s, with a small bay roof whose void opens into the main loft, and a chimney stack through the middle.
The foam
Ordered in 2012 and bonded directly to the slates and lime torching. The leaflet describes open-cell foam; at a roofer's cut-out it looked rigid and closed-cell. Measured 25 to 83 mm thick, against 40/50 mm ordered.
The paperwork
Order, terms, leaflet and brochures only: no completion document, installation date, product approval or roof survey, and no sign the ringed insurance-backed warranty was issued. Ordered 60 m²; measured about 53 m².
Why they called
With a quote for a new roof, the homeowner wanted an independent second opinion.
What was measured
- 20 timber readings, 12 at or above 20%. Away from the chimney, 18% to 20.6%; the six highest sat round the stack, up to 32.6%.
- Loft air 2.9 g/kg wetter than outside, and 1.5 g/kg wetter than the landing below.
- Highest dew point 13.6 °C, coldest surface 19.0 °C: a 5.4-degree margin.
- Eaves filled with foam down to the wall top in every rafter bay seen, where guidance expects about 0.072 m² of opening per side.
What it means
Here the loft air was wetter than the landing, which the report says air rising through the ceiling cannot explain on its own: something is adding moisture inside the roof. The bathroom fan blows into the chimney where the six highest readings sat: in the inspector's opinion, the most likely explanation for them. Elsewhere, readings spread across both slopes rather than under one point: in the report's reading, trapped moisture, not a leak.
What happened next
First, a roofing or chimney contractor to trace the duct inside the stack, check the flue and advise whether the fan can vent outside. Then two more itemised quotes, each roofer asked in writing whether the whole roof needs replacing or a repair would do, and how the eaves will let air in again. Then the warranty requested, and the bay and chimney timbers checked again after a winter.
For other homeowners
Before anyone prices a new roof, find where each loft extract fan ends: here one blew into the chimney, beside the six wettest readings.
Read the guide: Do you need to remove spray foam? Removal, costs and what to check first · Spray foam cold calls and removal scams: how to check a caller
The honest limit
One warm afternoon, not a winter night. Timber and slates behind the foam were not seen, stored belongings blocked the lower slopes, and the foam type is by appearance only.