Is there spray foam in my loft?
No spray foam found, but rafter after rafter carried marks consistent with condensation
East Hampshire · Recent inspection · Spray Foam Inspection
The house
Two-storey end-terrace with a single-storey rear extension. Concrete tiles on non-breathable bitumen felt, trussed rafters, 21.0° pitch. Mortar-bedded ridge, solid soffits, no gable vent.
The foam
None anywhere reachable in the main loft, and no sign any had been taken off. Floor insulation in two layers: 4 to 5 inches deep in one place, 9 to 10 in another, missing at the edges.
The paperwork
No installer paperwork, warranty or product approval was provided. Both energy performance records, seven years apart, show loft floor insulation only.
Why they called
The client needed to know, on evidence, whether there was spray foam in the roof.
What was measured
- Six timber readings from 5.6% to 11.6%; the lowest at the foot of a stained rafter, near the eaves.
- Loft air just 0.1 g/kg above outside, but ridge and mid-loft 1.3 g/kg apart, indicating air getting in but not moving across.
- Coldest surface 18.7 °C, 3.6 degrees above the loft dew point, in an empty house on a mild summer morning.
- Eaves open with daylight at seven points and packed with insulation at four.
- Clear rust on one plate at the eaves and two nail shanks; plates further into the roof clean.
What it means
The telling mark was on more than a dozen rafters: a white chalky deposit where the timber meets the felt, then dark staining down to the eaves. In the inspector's reading, water formed on the cold felt, evaporated at the timber leaving minerals, and the rest ran down; a leak would typically mark worst where it landed. The report finds this consistent with damp air from the house rising through bare patches, an unsealed hatch and gaps round a pipe.
What happened next
A roofer on the roof first: the felt is torn in three places and the covering was seen only from the ground. Then the bathroom extract duct and the two unidentified roof pipes. Ventilation and insulation after that.
For other homeowners
Here, no spray foam did not mean no problem. The edges of the loft insulation, the hatch and pipes through the ceiling are where a house's damp air can get into the loft.
Read the guide: How do I know if I have spray foam insulation? · Living with spray foam: should I worry?
The honest limit
Readings were taken in an empty house: a best case. The covering was seen from the ground only, so water coming in was not ruled out; one end of the loft and the extension roof void were not reached.