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Gwynedd · Wales

Damp investigation after cavity insulation in Gwynedd

For homes, landlords and businesses in Gwynedd, a damp investigation comes with a clear price and a plain-English record. A damp investigation finds out why an insulated wall is showing damp or mould: rain getting in through defects, bridged or wet fill, debris in the cavity, a breached damp-proof course, or condensation.

Moisture meter held against a damp, mould-spotted corner of an external wall indoors

Book a damp investigation in Gwynedd

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We use your details only to answer this enquiry and arrange your visit, sharing them only with the registered installer we appoint for your job and the providers named in our privacy notice. No marketing lists, no cold calls.

Damp investigation after cavity insulation across Gwynedd

We cover 4 towns in Gwynedd: Bangor, Caernarfon, Holyhead and Porthmadog.

Wind-driven rain is the first thing the surveyor weighs up. Parts of Gwynedd face some of the heaviest wind-driven rain in the UK, especially exposed coastal and upland sites. Here the survey is stricter: some walls suit only certain certified systems, and some should not be filled at all.

Where a Gwynedd wall does need work, bricks are lifted and rebuilt in matching mortar, and the cavity is checked with a camera before it is closed up. If your Gwynedd installation has a guarantee, we check it first; the guarantee route may cover the work.

Building Regulations in Wales

In Wales, filling an existing cavity is also notifiable building work under the Building Regulations as they apply in Wales. A registered installer normally self-certifies it through a competent person scheme; otherwise a building notice goes to your council's building control before work starts. Welsh rules can differ from England's, so the notification route is confirmed in writing on your quote.

Sources: Welsh Government: building work competent person schemes; CIGA: CWISC competent person scheme; Welsh Government: issues arising from cavity wall insulation installations.

Common causes we check

Defective pointing, cracked render and porous bricks letting rain in; leaking gutters and downpipes; fill bridging the cavity where mortar droppings or debris have collected; ground levels above the damp-proof course; and condensation from cooking, drying clothes and too little ventilation.

What is included

  • Moisture mapping inside
  • External defects check
  • Borescope at affected areas
  • Cause and options in writing

Damp investigation after cavity insulation prices in Gwynedd

Damp investigation after cavity insulation guide prices
Damp investigation after cavity insulation guide pricesGuide price
Damp investigation with borescope£295–£495

This work is not insulation, so it is normally standard-rated for VAT. Guide prices include VAT where it applies. Guide ranges only: the fixed price is confirmed in writing before any work starts, and anything that could not be seen at survey is agreed with you first.

From enquiry to finish in Gwynedd:

  1. Get in touch

    Online, by phone or WhatsApp.

  2. Your price

    Confirmed in writing before you book.

  3. The visit

    Carried out at an agreed time, with photos of what we find.

  4. Your report

    Plain English, with any follow-on work quoted separately.

Last reviewed 19 October 2026.

Damp investigation after cavity insulation in Gwynedd: questions

Do you cover all of Gwynedd?

Yes. We cover 4 towns across Gwynedd, including Bangor, Caernarfon, Holyhead and Porthmadog, and the villages around them. Island and remote addresses are surveyed by arrangement.

Will you tell me if I do not need any work?

Yes. If the findings show nothing needs doing, or a cheaper fix such as clearing a gutter will do, we say so.

Do you cold-call in Gwynedd?

No. We only come out when you have asked us to. If someone cold-calls offering free insulation, check before you agree to anything.

Do you work on rented homes in Gwynedd?

Yes. Landlords and agents in Gwynedd can book batch visits, and work is arranged around tenants.

Damp investigation after cavity insulation in nearby areas

Book a damp investigation in Gwynedd

Priced before you book. Findings in writing. No cold calls.