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Causes
27 August 2026

Mould in the attic or roof space: causes and risks

Quick answer

Attic mould is usually caused by poor roof-space ventilation, warm moist air rising from the home and condensing on cold roof timbers, or a roof leak. Improve ventilation and fix any leak — untreated, it can damage timber and insulation.

Why attics develop mould

Roof spaces are prone to mould when warm, moist air from the home below rises into the cold attic and condenses on the underside of the roof and on timbers. Poor attic ventilation traps that moisture, and mould follows. A roof leak makes it worse.

What to look for

Not sure how bad yours is?

Book a €75 inspection and know for certain — or call us now.

Dark staining on roof timbers and the underside of the roof, a musty smell when you open the hatch, damp or compressed insulation, and frost or water droplets on cold mornings. Because attics are rarely visited, problems can develop unseen for a long time.

Why it matters

Attic mould can rot roof timbers, ruin insulation and let spores drift down into the living space. Because it involves the structure, it's worth addressing rather than ignoring.

What to do

Improve roof-space ventilation, seal gaps that let warm moist air up from below, and fix any leak promptly. Where timber or large areas are affected, get it assessed — professional mould removal deals with contaminated material and an mould inspection identifies whether it's condensation or a leak.

Mould in your roof space? book a €75 inspection for an assessment, or call +357 96 738151.

Frequently asked questions

What causes mould in an attic?
Poor ventilation, warm moist air rising and condensing on cold roof timbers, and roof leaks are the main causes of attic mould.
Is attic mould dangerous?
It can rot roof timbers, damage insulation, and let spores drift into living areas. It's worth treating rather than leaving.
How do I stop mould in my roof space?
Improve attic ventilation, seal gaps letting warm air up from the home, fix leaks, and keep insulation dry.
How can I tell if my attic has a leak or condensation?
Localised staining and drips point to a leak; widespread damp and frost on timbers point to condensation. An inspection distinguishes them.

Not sure how bad yours is?

Book a €75 inspection and know for certain — or call us now.

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