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County Londonderry · Northern Ireland

Damp investigation after cavity insulation in County Londonderry

For homes, landlords and businesses in County Londonderry, 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 County Londonderry

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Damp investigation after cavity insulation across County Londonderry

We cover 4 towns in County Londonderry: Derry, Coleraine, Limavady and Magherafelt.

Exposure matters for every cavity wall. Parts of County Londonderry 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.

Damp in an insulated County Londonderry home is not always the insulation's fault, so the diagnosis comes before any extraction. Defects such as failed pointing, leaking gutters and bridged damp-proof courses are listed and priced separately for County Londonderry properties, so you can choose who fixes them.

Building control in Northern Ireland

In Northern Ireland, inserting insulation into an existing cavity wall needs a building control application to your council before the work. We make sure the application route is agreed and confirmed in writing before any drilling starts.

Sources: Building Control NI: frequently asked questions; Belfast City Council: what are the building regulations.

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 County Londonderry

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 County Londonderry:

  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 County Londonderry: questions

Do you cover all of County Londonderry?

Yes. We cover 4 towns across County Londonderry, including Derry, Coleraine, Limavady and Magherafelt, 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.

How much does a damp investigation cost in County Londonderry?

Guide prices are shown on this page, and the price for your County Londonderry property is confirmed before you book.

Do you work on rented homes in County Londonderry?

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

Damp investigation after cavity insulation in nearby areas

Book a damp investigation in County Londonderry

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