Warmshell Internal is ideal for hard to heat homes

You can use Warmshell Internal in almost any situation. However, it’s particularly well-suited to historic, hard to heat homes, irrespective of whether they are brick, masonry or timber frame.

In these situations, the breathability of Warmshell, and its ability to buffer and control moisture, is particularly helpful.

Warmshell Internal is a highly breathable IWI (Internal Wall Insulation) system that is fitted to the inside of walls and roofs.

It comprises of three key components:

  1. Warmshell Board Adhesive
  2. Warmshell Woodfibre Boards
  3. Lime Green Solo onecoat plaster

Warmshell Internal is a practical solution when fitting insulation to the outside of your property isn’t an option. That could be because you can’t get access, you don’t own the whole property, or you can’t change the look of the building, for example if you live in a conservation area or your home is part of a terrace.

Also, with Warmshell Internal, there is no need to hire scaffolding, negotiate access with neighbours or think about external finishes – because everything’s done inside your home.

Warmshell Internal is proven to manage and control moisture in your walls. Wood has evolved to store and transport moisture, and Warmshell Woodfibre can wick and buffer water through a wall in a way no other insulation can. Our lime plasters are developed to work specifically with the woodfibre, to keep your house warm and dry.

And unlike some insulations Warmshell Internal does not contain formaldehyde, biocides or VOCs. By sandwiching the insulation between two layers of lime - the Warmshell Board Adhesive on the back and the Lime Green Solo on the front - oxygen needed for mould and rot is excluded. Even better, lime is naturally anti-bacterial, killing and sterilising as it is applied without using persistant toxic additives.


Easy to install

Installing Warmshell Internal in the interior of your home is surprisingly straightforward.

It is well within the reach of a capable DIYer, and should be second nature to most builders. It is also much easier and more comfortable than using mineral wool alternatives.

All you need to do is follow a simple, five-step process:

  1. Move furniture and furnishings so that your exterior-facing walls can be accessed (internal walls aren’t affected)
  1. Scour the wall with a coat of Lime Green Duro lime plaster base coat to ensure a completely level surface
  1. Cut the Warmshell Woodfibre boards to size and aim to cover as much as the wall surface as possible (cables for sockets and light switches may need to be extended through the insulation, though this isn’t always necessary)
  1. Secure the Warmshell Woodfibre boards to the wall surface using Warmshell Board Adhesive
  1. Plaster over the Warmshell insulation boards with two-passes of our one coat lime plaster Lime Green Solo, to achieve an 8-to-10mm covering.


Watch how easy it is to install

Warmshell Internal Documents

We are here to support you throughout the installation process. Download our guides and certificates by clicking on the buttons below. And, if you ever want more advice and guidance, give us a call.

We are here to support you throughout the installation process.




Guideline specifications and drawings for Warmshell Internal with woodfibre and lime plaster.

 Specification Clauses



See the difference Warmshell Internal can make to the heat loss in a historic solid wall property. 

U values



Fitting our Warmshell Internal insulation system is a simple process to help insulate your building.

Installation Guide



Warmshell Internal is the only woodfibre insulation system independently tested & classified by a UKAS acredited laboratory.

 Fire Certificate


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To help you on your way, we also offer training, and can put you in touch with a wide network of system-trained installers.

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