Internal wall insulation · Wales
Internal wall insulation in Gwynedd
Planning internal wall insulation anywhere in Gwynedd? We cover towns including Bangor (Gwynedd) and Holyhead, and check planning and building control for each address. We plan internal insulation in Gwynedd homes room by room so you keep the rest of the house usable.
- Free survey and fixed written price
- Guide price from £75 per m² 0% VAT
- Planning and building control checked for Wales
Free survey in Gwynedd
Tell us the postcode and what you need.
Part of every quote
- Loses roughly 50–100mm per insulated wall
- Can be done one room at a time during a renovation
- Insulated plasterboard, stud wall or breathable systems
- Keeps the outside of the house exactly as it is
- Sockets, radiators, skirting and coving are moved and refitted
Before we quote in Gwynedd
North Wales has many solid stone and slate-built homes, Victorian seaside terraces and post-war council estates.
Parts of Gwynedd fall in the higher wind-driven rain exposure bands, especially coastal and upland sites, so render specification, movement joints and detailing at cills, verges and the base of the wall matter more than usual.
We plan internal insulation in Gwynedd homes room by room so you keep the rest of the house usable.
- Nation
- Wales
- Region
- North Wales
- Towns covered
- Bangor (Gwynedd), Holyhead, Caernarfon, Llangefni
- Guide price
- From £75 per m² 0% VAT
Wales: planning and regulations
Internal insulation rarely needs planning permission, but in England and Wales insulating or replastering more than half of a wall's area involves building control, and listed buildings need consent for internal changes that affect their character.
The Building Regulations as they apply in Wales treat insulating or re-rendering more than half of a wall's area, or more than a quarter of the building's whole envelope, as renovating a thermal element, with Approved Document L (Wales) setting the target. Building control is involved before work starts.
What are the options for internal insulation?
- Insulated plasterboard — PIR or phenolic foam bonded to plasterboard, fixed to the wall and skimmed. Thinnest option.
- Insulated stud wall — a timber or metal frame filled with insulation, with a vapour control layer and plasterboard. Takes more space but runs services easily.
- Wood fibre and lime — breathable boards finished in lime plaster, for older walls that need to manage moisture.
Internal wall insulation prices in Gwynedd
| Item | Guide price | Notes |
|---|---|---|
| Insulated plasterboard, supplied and skimmed | £75–£110 per m²0% VAT | |
| Insulated stud wall | £90–£130 per m²0% VAT | |
| Typical bedroom, one external wall | £1,795–£2,9950% VAT | Including making good |
Confirmed by a fixed written quote after survey. 0% VAT: installing insulation in a home is zero-rated until 31 March 2027, so these figures are the total; 5% applies from 1 April 2027.
How it works
Get a guide price
Try the online quote tool for a ballpark figure.
Book the survey
A visit at a time that suits you.
Agree the quote
Nothing starts until you've signed the written price.
We do the work
Planned around weather, with you kept informed.
Internal wall insulation in Gwynedd: questions
What happens to my radiators and sockets?
They're taken off and refitted on the new wall face. Electrical work is done by a qualified electrician.
Is internal insulation cheaper than external?
Per m² usually yes, but the cost of moving fittings and redecorating narrows the gap on whole-house jobs.
Can I stay in the house?
Yes, but each room is out of use while it's worked on, typically 3–5 days.
Do you cover all of Gwynedd?
Yes. We survey and quote internal wall insulation across Gwynedd, including Bangor (Gwynedd), Holyhead, Caernarfon, Llangefni.
Do I need planning permission in Wales?
Permitted development rules for houses in Wales are similar to England's: a similar-appearance finish on a house is often permitted, while conservation areas, National Parks, Areas of Outstanding Natural Beauty, flats, commercial buildings and listed buildings need permission or consent. We check your address before quoting.