Thermographic Survey in Farnham

The town has a broad housing mix, and that matters for thermal performance. Local ward data shows detached homes at 35.8%, semi-detached at 28.1%, terraced at 20.1% and flats or maisonettes at 15.6%, while the built-up area recorded 40,096 residents and 16,339 households in 2021. Age profile data is just as telling, with 18.2% pre-1919, 14.5% from 1919-1945, 32.1% from 1945-1980 and 35.2% post-1980. That spread creates very different heat-loss patterns from one street to the next.

Pre-1919 homes around Castle Street and West Street usually have solid 9-inch or 13-inch brick or Bargate stone walls, timber floors and pitched roofs finished with clay tiles or slate. Those buildings were never designed for modern insulation depths, so retrofits can leave cold bridges at reveals, joist ends and roof junctions. Homes from 1945-1980 more often have cavity walls with brick outer leaves and block inner leaves, yet older steel wall ties, thin loft insulation and patchy retrofits can still leak heat. Post-1980 homes in GU9 and GU10 usually perform better, but render cracks, unsealed service penetrations and timber cladding details can still show up on thermal scans.

Farnham sits on Folkestone sandstone and Gault clay, so the ground can move differently from one street to the next. Moderate to high shrink-swell risk in clay pockets can open gaps at junctions, while river-side and surface water flooding near the Wey can drive damp into floors and walls. In conservation areas around Castle Street, Downing Street and West Street, original fabric often stays in place for longer, which makes infrared work useful because many defects sit behind finishes that cannot be disturbed lightly. The survey is a good fit for listed buildings too, because it shows where heat is escaping without altering the building.

Blue and purple usually show cooler surfaces, while red and white mark warmer areas. A narrow cold streak along a skirting board can mean air leakage, while a broad cool patch may signal insulation voids. The image only becomes useful when the temperature pattern is read alongside the building type and the weather on the day. That matters on a GU9 terrace just as much as on a GU10 detached home.

External scans need care. Sun on a south-facing elevation can warm brickwork unevenly, and a reflective surface such as glazing can throw false readings back into the camera. Wet render, a freshly heated room or strong wind across the River Wey side can also distort the pattern, so our surveyors interpret the image rather than rely on colour alone. That is why a thermal image is evidence, not a diagnosis on its own.

Each report labels the problem area, records the temperature difference and explains the likely cause in plain language. If a ceiling patch cools after heating, we may flag missing loft insulation or disturbed quilt, while a localised damp zone near a bathroom stack could suggest a leak that needs further investigation. That level of explanation helps when the next step is an EPC upgrade, a builder quote or a conversation with a conveyancer during a purchase. It also makes the findings easier to compare with a standard survey or a retrofit plan.

Our thermographic surveys start from £300. That usually covers external and internal infrared scans, an annotated report and practical recommendations, with the survey itself taking 1-2 hours depending on property size. Against Farnham's overall average house price of £677,951 according to homedata.co.uk, the cost is small compared with catching missing insulation, draughts or damp before they become bigger repairs. It is a sensible check before purchase, sale or retrofit work.

Best results come from a cool, dry day between October and March, with at least a 10C difference inside and outside. We ask for the heating to be on for 2 hours before the appointment, because steady indoor warmth makes the thermal patterns easier to read. Larger detached homes near the town centre conservation area or plots with extensions may need more scanning time because there are more junctions, roofs and elevations to inspect. Once the images are reviewed, the report follows with the annotated findings and action points.