Internal Wall Insulation (IWI)

Internal Wall Insulation (IWI) can help improve the thermal efficiency of your project. It is suitable for many types of construction including solid walls and cavity walls. STEICO’s internal wall insulation products offer a range of key features which can benefit your project.

What is internal wall insulation? And how does it work?

Internal wall insulation can be used on both solid walls and cavity walls. When specified and installed correctly, it can improve the thermal efficiency and fabric of your home. It can be used as an alternative to external wall insulation, or in addition to it if required.

There are several methods of installing internal wall insulation, including:

Fixing it directly to the wall using adhesive or screws. Requires the addition of a vapour barrier.
Battening the wall, then attaching insulation to the battens.
Creating a new stud wall with a small cavity to the existing wall.
In combination with insulating plaster, a method most commonly used on stone walls.

The insulation used will depend on the system you choose. However, most types of insulation are suitable including rigid boards, flexible infill insulation or air-injected insulation.

Before installing anything, ensure the wall is in good condition, consider how to deal with any voids or potential cold bridges and have a plan for retaining any plug sockets or light switches that are present on the existing wall.

The potential challenges of internal wall insulation

Internal wall insulation can be more cost-effective compared to external wall insulation, but it does come with some challenges that you need to be aware of, including:

Floor space – Installing internal wall insulation means that you will lose some floorspace in your home. Utilising a system which compliments your building fabric can help you to select an appropriate thickness.
Condensation and damp – Adding a layer of interior insulation raises the risk of condensation and damp if the system is not specified and installed incorrectly. You may need to create a continuous, unperforated vapour barrier to limit potential cold points and damaging condensation.
Disruption – Interior insulation requires you to move sockets, switches, cabinets, mirrors, pictures and anything else attached to the wall in the affected area. You will need to reinstall all of these elements.

The features and benefits of STEICO internal wall insulation

STEICO interior wall systems have been designed to limit the potential downsides of this type of insulation. Key features which could benefit your home include:

Thickness – STEICO interior wall insulation can improve thermal performance with a 40-60mm layer which helps to limit the impact on internal floor space.
Wood fibre structure – Diffusion-open wood fibre structure allows moisture to be absorbed, distributed and quickly dried through evaporation, reducing the risk of condensation, mould and potential structural and health risks associated with excess moisture.
Thermal and acoustic performance – STEICO internal wall insulation offers both thermal and acoustic insulation in a single layer.
Easy to modify and install – STEICO interior insulation can be modified using standard tools for ease of installation on site.
Sustainability – Our wood fibre interior wall installation products are manufactured from PEFC certified timber (PEFC/04-31-2550), bind carbon through Lifecycle Stage A1 as defined in EN 15804+A2 and can play a role in reducing operational carbon emissions in the finished building.

We offer two interior insulation systems to suit different needs. The first is a single-layer internal wall insulation system which is made up as follows: