External wall insulation

Wood fibre external wall insulation

Wood fibre external wall insulation uses dense boards made from compressed wood fibres, finished with lime or mineral render. It is vapour-open and moisture-buffering, which makes it a good match for stone and older solid walls that need to stay breathable.

Vapour-open and hygroscopic — buffers moisture rather than trapping it
Compatible with lime renders used on traditional buildings
High density gives good protection from summer heat
Made from a renewable material with low embodied carbon
Thicker than foam for the same U-value
Often the most suitable EWI where planning allows on older properties

Get a guide price See prices

Brown wood fibre insulation boards fixed to an old stone cottage wall, with part of the wall already in lime render

Free survey for wood fibre EWI

Tell us about the property. We reply on working days.

Postcode *

Enter a valid UK postcode.

Service *

Choose a service.

Name *

Enter your name.

Phone *

Enter a phone number we can call.

Email (optional)

Check the email address.

About the job (optional)

We use your details only to respond to this enquiry. See our privacy notice.

Why do older walls need breathable insulation?

Stone and early brick walls were built with lime mortars and renders that let moisture in and out. Sealing them with impermeable materials can trap water in the wall, leading to damp and frost damage. Wood fibre keeps the build-up open to vapour, and its ability to absorb and release moisture helps the wall stay in balance.

Typical build-up

Board: Wood fibre, typically 160–240 kg/m³
Conductivity (λ): ≈0.040–0.048 W/mK
Typical thickness: 80–160mm
Finish: Lime or mineral render system
Vapour: Open and moisture-buffering

What finish goes over wood fibre?

A lime-based or mineral render designed for the system, applied over a reinforcing base coat. Lime finishes give the softer, slightly irregular texture that suits cottages and older terraces.

What about listed buildings and conservation areas?

EWI on a listed building needs listed building consent and is often refused where the outside appearance matters. In conservation areas, rendering or cladding a house normally needs planning permission. Wood fibre and lime are more likely to be acceptable than foam and acrylic, but the council decides. We check before quoting.

Wood fibre insulation for older homes prices

Wood fibre insulation for older homes guide prices
Item	Guide price	Notes
Wood fibre + lime render system	£150–£210 per m²0% VAT	Excluding scaffold
Cottage, about 90 m² of wall	£15,300–£22,1000% VAT	Including scaffold
Lime render only (no insulation)	£78–£132 per m²inc VAT	See lime render

Guide prices are confirmed by a fixed written quote after a free 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. Prices include VAT at 20%.

How it works

Tell us about the property
Use the quote tool or form, or call free on 0800 088 6248.
Free survey
We measure the walls, check condition and confirm planning and building control.
Fixed written quote
The system, details, access, exclusions and VAT, in writing. Anything hidden is priced and agreed before extra work.
Installation and handover
Work planned around the weather, then inspected and documented.

Wood fibre insulation for older homes: questions

Is wood fibre insulation fireproof?

No — it's a timber product. It chars rather than flaming readily, but it is combustible, so it's used on low-rise buildings within a tested system and never where non-combustible materials are required.

Is wood fibre worth the extra cost?

On older solid walls the main benefit is moisture safety rather than raw U-value. If the wall needs to breathe, the cheaper option can cost more later.

Can wood fibre go on a stone wall?

Yes, after levelling. Rubble stone is often uneven, so a levelling coat or adapted fixing method is used first.

Does wood fibre need a lime render?

It needs the render specified by the system manufacturer, which is usually lime or mineral based.

Reviewed 19 October 2026 by the Render and Insulation technical team.