Condensation and mould ventilation fixes in Gwynedd and Anglesey

For tenants, landlords and homeowners in Gwynedd and Anglesey, the common question is why the mould keeps coming back.

We carry out condensation and mould ventilation fixes across Gwynedd and Anglesey, including Bangor and Holyhead. Prices use Wales rates. Surveys for new installations are free on the UK mainland, with a written quote afterwards.

Condensation & mould in Gwynedd and Anglesey at a glance

Area: Gwynedd and Anglesey, Wales
Towns listed: 2, largest Bangor
Postcode districts: LL58, LL65 and LL57
Price region: Wales
Survey: Free survey (UK mainland)

What the work involves

If extract fans are weak, ducted into the loft or switched off, and windows stay shut in winter, that moisture settles on the coldest surfaces: window reveals, external corners, behind wardrobes and on bathroom ceilings. Mould needs that damp surface to grow. Ventilation is usually the biggest part of the cure, but not the only part.

Survey and findings

Humidity and surface readings, existing fans flow-tested, and a written list of causes and fixes.

Fan upgrades

Weak or loft-vented fans replaced and ducted outside, with humidity control.

Whole-home ventilation

PIV, continuous extract or MVHR where moisture is spread through the house.

Guide prices in Gwynedd and Anglesey

Condensation and mould ventilation fixes guide prices in Gwynedd and Anglesey
Work	Guide price
New ducted fan to outside through the loft or ceiling (insulated duct, roof or soffit outlet) (per fan)	£425–£700 inc VAT
Positive input ventilation (PIV) loft unit, supplied and fitted (per home)	£750–£1,325 inc VAT
Continuous-running extract fan (dMEV) with humidity boost, flow tested (per fan)	£330–£575 inc VAT
Condensation and mould ventilation survey with written findings (per home)	£120–£215 inc VAT

These ranges use our Wales rates. Prices include VAT at 20%. You get a fixed written price before any work is booked.

When to get it looked at

Black mould on window reveals, ceilings or behind furniture
Water running down windows on cold mornings
Musty smell in bedrooms or wardrobes

Rules in Wales

Wales has its own Part F ventilation guidance, published by the Welsh Government, and work is checked by building control. Rented homes in Wales must be fit for human habitation under the Renting Homes (Wales) Act, and damp and mould is one of the matters considered.

How the job runs

Survey
Find the cause
Recommend
Fix
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Towns we cover in Gwynedd and Anglesey

Questions about condensation and mould ventilation fixes in Gwynedd and Anglesey

Is the survey free in Gwynedd and Anglesey?

For new installations on the UK mainland, yes. The survey is free and the quote that follows is fixed and in writing. Servicing, testing and repair visits are charged, and we confirm the cost before booking.

Is PIV or MVHR better for condensation?

For most existing homes with general condensation, PIV plus good extract fans is the most cost-effective fix. MVHR suits airtight, well-insulated homes and full renovations.

How much does a condensation survey cost?

A ventilation survey with written findings costs £125 to £225 including VAT. If we are surveying for an installation we quote for, the survey is free.

Which rules apply to ventilation in Gwynedd and Anglesey?

In Wales, the Welsh Government's own Approved Document F (2022 edition) applies to ventilation in homes, with a new edition taking effect on 4 March 2027. Rented homes must be fit for human habitation under the Renting Homes (Wales) Act 2016, and workplaces must be ventilated under the Workplace (Health, Safety and Welfare) Regulations 1992.

Which towns in Gwynedd and Anglesey do you cover?

All of Gwynedd and Anglesey, including Bangor and Holyhead. If your town is not listed, send the postcode and we will confirm.

Book a condensation survey in Gwynedd and Anglesey and get a written list of causes and fixes.