What UK Surveyors Look For With Spray Foam Insulation

Knowing what a RICS surveyor will look at — and write down — when they encounter spray foam is invaluable preparation, whether you are remortgaging, selling, or simply weighing up the case for removal. This guide walks through the realistic surveyor's checklist used across the UK in 2026.

First look at the loft hatch

The inspection begins the moment the hatch opens. A surveyor will note immediately whether foam is visible, what colour and apparent density it is, whether it is sprayed between rafters or onto the felt, and whether the eaves vents are still functional. These observations all go into the report.

Inspectability of the structure

RICS guidance is explicit that structural elements which cannot be visually inspected must be flagged as a limitation. Foam-coated rafters trigger this clause automatically. The wording typically reads 'inability to inspect roof structure due to applied insulation' and is the single most common cause of lender refusals.

Ventilation assessment

Surveyors check eaves vents, soffit vents, ridge vents and any installed mechanical ventilation. Where foam has bridged or blocked these, the report notes 'inadequate roof void ventilation' as a contributory defect. Even open-cell installations frequently fail this check.

Moisture and condensation indicators

Dark staining along rafters, salts crystallising on roof timbers, water marks on insulation surfaces, and visible condensation droplets all get recorded. The presence of any of these escalates the report from a simple 'inspectability' flag to a probable defect requiring further investigation.

Timber probing where access allows

Where any rafter end is exposed at the wall plate, surveyors will probe with a small tool to test for softness. A spongy response indicates active or recent decay. This is one of the few non-destructive tests possible without removal.

External roof condition

From outside, surveyors look for tile slippage, sagging between rafters, ridge displacement and any signs of water ingress. Spray foam can mask internal water tracking, so external evidence becomes more important than usual.

Documentation requested

Surveyors will ask for the original installation paperwork, any guarantee, and the installer's specification. In many UK cases the installation pre-dates the current owner and no paperwork exists. This is itself a flag.

What ends up in the lender's hands

The valuation report sent to the lender will typically state the roof is not inspectable, recommend full removal by a qualified specialist, and either down-value the property or attach a retention pending removal. The lender then makes the underwriting decision based on this wording.

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