Wall Insulation
Here at SOPREMA, we offer a variety of thermal insulation products suitable for wall applications.
Wall insulation refers to materials installed within the wall build-up or applied to wall surfaces. The SOPREMA range of polyisocyanurate (PIR) insulation boards are designed for use in wall systems and act as a thermal barrier within the building envelope.
When installed properly, and in conjunction with roof and floor insulation to create a thermally efficient building envelope, wall insulation primarily helps prevent heat loss in winter, while also reducing the rate of heat gain during warmer periods.
Preventing heat transfer in a building could reduce energy demand and energy bills, while also keeping interiors at a more comfortable temperature for building occupants.
Insulating external walls also supports efforts to meet the thermal performance requirements of Approved Document L (Conservation of Fuel and Power) and aligns with the direction of the upcoming Future Homes and Buildings Standards.
When used as thermal wall insulation, SOPREMA PIR rigid boards can be installed in wall cavities (cavity wall insulation), timber frame walls or solid walls (solid wall insulation).
The different types of wall constructions and wall insulation methods:
In the UK, external walls are most commonly constructed from masonry. Depending on how the masonry wall is constructed, different insulation strategies will be required:
Cavity Walls
Most buildings constructed since the 1930s feature cavity walls, which consist of two layers of masonry separated by a gap. The insulation options for masonry cavity walls are partial-fill cavity wall insulation or full-fill cavity wall insulation.
Solid Walls
Buildings constructed before the 1930s usually have solid walls consisting of a single layer of masonry and no cavity. Insulation can be positioned internally or externally to existing solid walls. Specialist advice should be sought in relation to the correct solution for the solid wall for each individual property.
Not all walls are constructed from masonry; some use timber or metal framing. In these systems, insulation is typically installed between the frame elements and either internally or externally to the frame.
SOPREMA wall insulation products
SOPRATHERM wall insulation is manufactured from PIR, a rigid foam insulation material. PIR is created through a chemical reaction that produces a closed-cell structure that traps low-conductivity blowing agents. This structure gives PIR boards their low thermal conductivity, which helps to reduce heat loss through external walls while also providing moisture resistance and dimensional stability.
PIR insulation has a typical density of around 30 kg/m³, making it lightweight. This can make it easy to transport, handle and position on site, supporting more consistent installation practices. SOPREMA Wall products are BBA-certified, and their low thermal conductivity contributes to helping designers, specifiers and installers create wall build-ups capable of meeting the energy efficiency requirements of Approved Document L.
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A rigid PIR insulation designed for masonry full-fill or partial-fill cavity wall applications, provides a thermal conductivity of 0.021 W/m·K. |
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Tailored for partial-fill cavity walls, these boards come in various thicknesses (40mm to 100mm) and provides a thermal conductivity of 0.022 W/m·K. |
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Brings together both insulation and plasterboard creating a 2-in-1 solution to insulate and dry line walls at the same time, and they provide a thermal conductivity of 0.022 W/m·K. |
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PIR foam boards with a thermal conductivity of 0.022 W/m·K. They are multi-application boards be used alongside separate plasterboard layers which can be used for drylining and timber frame. |
Why Insulate Your Walls?
Current energy costs1 and regulatory requirements highlight the need for developing energy-efficient buildings. Wall insulation reduces heat loss, helping to minimise the amount of energy required to keep the building warm. This can help to reduce heating bills and enhance occupant comfort.
Thermal wall insulation also helps meet legal requirements for energy efficiency. Approved Document L sets thermal performance standards in England, expressed as U-values. The required U-value applies to the complete wall build-up. Insulation is specified to ensure that, in combination with other building materials, the complete wall achieves the necessary U-values.
Volume 1 of Approved Document L (2021) sets a notional U-value for walls in new-build dwellings or extensions of 0.18 W/m²·K. The limiting value is 0.26 W/m²·K. For refurbishment projects, the improved U-value is 0.55 W/m²·K for cavity wall insulation and .30 W/m²·K for internal or external insulation on other walls.
For buildings other than dwellings, Volume 2 sets a limiting value of 0.26 W/m²·K for walls in new builds. For refurbishment projects, the improved U-value is 0.55 W/m²·K for cavity wall insulation and 0.30 W/m²·K for internal or external insulation on solid walls.
For Wales, Scotland and Northern Ireland, similar requirements exist:
- Wales: Approved Document L (Wales) – Conservation of fuel and power
- Scotland: Section 6 of the Scottish Building Standards – Conservation of Fuel and Power.
- Northern Ireland: Technical Booklet F – Conservation of Fuel and Power.
SOPREMA provides a range of resources to support designers, specifiers and installers. Try our online U-value calculator to specify suitable roof insulation for your next project.
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1https://commonslibrary.parliament.uk/research-briefings/cbp-9491/
https://www.ons.gov.uk/economy/economicoutputandproductivity/output/articles/theimpactofhigherenergycostsonukbusinesses/2021to2024
https://www.ofgem.gov.uk/information-consumers/energy-advice-households/energy-price-cap-explained
External Walls
Insulation for External Walls
Building two skins of masonry (brick and/or blockwork) either side of an air cavity has been the most popular method for constructing external walls in the UK for about a century. From its development to address some of the flaws of traditional solid wall construction, it has gradually evolved in response to improving insulation technology and the development of building regulations relating to energy efficiency.
In a full-fill masonry cavity wall the residual cavity between the two leaves of masonry is entirely filled with insulation. Third-party accreditation in the form of BBA certification means that the insulation is guaranteed not to allow wind-driven rain to penetrate across the cavity, ensuring that the wall retains its original function of keeping the inner leaf of the structure dry.
Timber Frame Walls
Insulation for Timber Frame Walls
An increasingly popular way of constructing new-build dwellings is to use a timber framed construction rather than traditional masonry cavity wall construction. Building with timber framed construction can offer a number of advantages and benefits over building with a more traditional form of construction, such as lighter weight and a higher speed of construction.
In a timber-framed wall, insulation is typically installed between the studs. This insulation can be PIR, SOPRATHERM GA4000 Or XR4000 (Previously known as Celotex GA4000 and XR4000) can be considered.
Depending on U-value requirements, there may be additional insulation required. This can be placed outside the sheathing board (i.e. within the external wall cavity); products such as SOPRATHERM GA4000 and XR4000 (previously known as Celotex GA4000 and XR4000) can be considered.
Insulation could also be installed internally on the warm side of the studwork, such as a plasterboard laminate (SOPRATHERM (Celotex) PL4000 can be considered) or a PIR insulation board (SOPRATHERM (Celotex) TB4000 or GA4000 can be considered) alongside a separate layer of plasterboard.
Masonry Cavity Walls
Insulation for Full Fill Masonry Cavity Walls
Building two skins of masonry (brick and/or blockwork) either side of an air cavity has been the most popular method for constructing external walls in the UK for about a century. From its development to address some of the flaws of traditional solid wall construction, it has gradually evolved in response to improving insulation technology and the development of building regulations relating to energy efficiency.
In a full-fill masonry cavity wall, the residual cavity between the two leaves of masonry is entirely filled with insulation. Third-party accreditation in the form of BBA certification means that the insulation is guaranteed not to allow wind-driven rain to penetrate across the cavity, ensuring that the wall retains its original function of keeping the inner leaf of the structure dry, if installed, used and maintained as set out in the certificate.
Solid Walls
Insulation for Solid Walls
For homeowners looking to improve the performance of their solid masonry walled properties - perhaps to achieve compliance with modern building regulations, or perhaps to go beyond that and meet a retrofit standard such as EnerPhit - adding more insulation material to the outer face of the wall is sometimes not possible.
Using an insulated plasterboard product such as SOPRATHERM (Celotex) PL4000, either adhered to the masonry inner surface or mechanically fixed to timber battens that are themselves fixed to the masonry inner surface, represents a potential option for improving the thermal efficiency of the wall without affecting its external appearance. Another option is a PIR insulation board (SOPRATHERM (Celotex) TB4000 or GA4000 can be considered) alongside a separate layer of plasterboard. Lightweight polyisocyanurate (PIR) foam boards from Celotex are easy to handle, and their thermal efficiency means thicknesses can be kept to a minimum, reducing lost floor space.
As part of a holistic approach to upgrading, you will also want to consider building fabric, airtightness and controlled ventilation along with improvements in thermal performance. For SOPRATHERM (Celotex) PL4000, the composite facing on the insulation board, behind the plasterboard layer, can form part of the air and vapour control layer when the tapered edge plasterboards are taped and jointed.
In all cases, specialist advice should be sought in relation to the correct solution for the solid wall for each individual property, especially in relation to moisture movement and the potential of condensation. Breathable membranes and dynamic hygrothermal calculations may need to be considered.
When using SOPREMA products, you need to satisfy yourself that use of the product meets all relevant national Building Regulations and guidance as well as local, national and other applicable standards relevant for your construction or application, including requirements in relation to fire and applicable height restrictions. In addition to the product datasheet, please refer to the following product documents:
- BBA certificates - where applicable to the application
- Declarations of Performance
- Health & safety datasheets
- Calculating the P/A ratio leaflet
Any Questions?
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