Room-in-roof insulation

What is room-in-roof insulation?

Most rooms-in-roof are reached by stripping the existing plasterboard on the slopes, fitting insulation between and over the rafters, and re-boarding. Where there is access behind the knee walls, we insulate the eaves voids and the floor behind them too. Dormer cheeks and roofs are included where they can be reached. The room will need redecorating.

Is it right for your loft?

An attic bedroom that is cold in winter and hot in summer
Older loft conversions with little insulation
An EPC that flags the room-in-roof
You are redecorating anyway

How we do it

We survey each part of the room: slopes, knee walls, flat ceiling, dormers and eaves voids.
We agree what gets stripped and what stays, and how you will use the room during the work.
Insulation goes in part by part, with ventilation kept where the roof needs it.
New boards are taped, skimmed or finished ready for decoration.

What is included

Insulation to slopes, knee walls and flat ceiling
Eaves voids insulated where accessible
Boarding and finishing as agreed on the quote

Worth knowing

This is a bigger job than loft insulation, usually several days, with dust and disruption. Building control may need to be notified where more than half the room's roof is renovated. We confirm the route on the quote.

How much does room-in-roof insulation cost?

£3,995 to £8,995One room-in-roof, depending on size and finish. Free survey and a fixed written quote before any work.

Part of this work can be zero-rated as energy-saving materials until 31 March 2027, and part is standard-rated. If VAT applies, your quote shows which is which.

Work out a guide price for your loft or see every price.

Do the rules differ across the UK?

Yes, a little. Building regulations and funding schemes are set separately in each nation. Here is the short version; each area page has the detail.

Nation	Building rules	Funding to check
England	Approved Document L; insulation alone is not usually notified	ECO4 to 31 Dec 2026; Warm Homes Plan and Warm Homes: Local Grant
Wales	Welsh Approved Document L; conversions need building control	Warm Homes Nest; ECO4 to 31 Dec 2026
Scotland	No building warrant normally needed; standards still apply	Home Energy Scotland grant and loan; Warmer Homes Scotland
Northern Ireland	NI Building Regulations (Technical Booklet F1); check with council building control	Affordable Warmth Scheme; NISEP

Questions about room-in-roof insulation

How long does room-in-roof insulation take?

Usually three to six working days for one room, depending on how much is stripped and how it is finished.

Can it be done without removing the plasterboard?

Sometimes the flat ceiling and eaves voids can be reached from behind. The slopes almost always need the boards off to insulate them properly.

Will the room get smaller?

Slightly. Insulated plasterboard over the rafters takes a few centimetres off each slope.

Where we provide room-in-roof insulation

Wales

Scotland

Northern Ireland

Often booked with it

Cold loft or warm loft: where should the insulation go?

Sources, checked October 2026: Energy Saving Trust: roof and loft insulation; Which?: loft insulation costs and savings; LABC: building regulation requirements for loft insulation; GOV.UK: extending the ECO4 end date, government response.