What is a wall insulation board?
A wall insulation board is a solid panel designed to improve a building’s thermal efficiency by reducing heat loss through walls. These boards are made from various insulating materials, each with distinct properties, including thermal performance, fire resistance, and moisture control.
How it works
Wall insulation boards are designed to slow the movement of heat between the inside and outside of your home. By fitting these panels internally or externally, you can cut heat loss by up to 35%, reduce carbon emissions, improve EPC ratings, and enjoy more consistent, comfortable indoor temperatures, whether you’re a homeowner, landlord, or builder.
Common applications
Wall insulation boards are widely used to upgrade energy efficiency in homes, apartments, commercial buildings, and social housing. You can install them inside on stud walls, fix them externally with render or cladding, or use them in cavity walls for systems that allow it, making them suitable for eco retrofits, new builds, or large-scale property upgrades.
Types of wall insulation boards
There are several types of wall insulation boards available, each suited to different needs and applications.
PIR insulation boards
Polyisocyanurate (PIR) insulation boards are a top choice for both internal and external walls due to their high thermal efficiency and slim profile. They’re ideal when you want excellent insulation performance without losing much living space, making them perfect for upgrades, rental properties, and compliance with modern building regs.
EPS/polystyrene boards
Expanded polystyrene (EPS) boards are lightweight and affordable, often specified for external wall insulation as part of smooth or textured render systems. They’re easy to handle, moisture-resistant, and compatible with most UK wall types, making them popular for large developments or cost-sensitive builds.
Phenolic insulation boards
Phenolic boards deliver superior insulation in the thinnest possible layers, which is key when you’re aiming for the lowest U-values (how successfully a material insulates) and minimum wall build-up. They’re especially well-suited for properties where space or performance takes priority, such as social housing or high-performance new builds.
Mineral wool boards
Mineral wool boards combine fire resistance, breathability, and acoustic insulation. They’re especially sought after for external wall systems in high-rise flats, public buildings, or anywhere fire regulations demand top-tier safety materials.
Best options for internal vs. external walls
For internal walls, PIR or phenolic boards are typically the best choice due to their slim profile and high insulation performance. For external walls, choose EPS for cost-effective upgrades, or mineral wool for buildings requiring superior soundproofing and fire safety, especially for government or public housing projects.
Benefits of wall insulation boards
Wall insulation boards come with a range of advantages that make them a smart investment for homeowners, landlords, and developers.
Energy efficiency & heat retention
Wall insulation boards dramatically slow heat loss through the walls, making your property warmer, cutting bills, and boosting your EPC rating for improved resale or rental value.
Noise reduction
Boards such as mineral wool and composite panels can significantly reduce noise transfer between rooms and from outdoors, improving living conditions for tenants and homeowners.
Fire resistance & safety
If fire safety is a priority, mineral wool and phenolic boards provide non-combustible options, crucial for conversions, flats, or contractor-led renovations in line with regulatory standards.
Cost savings
The upfront investment pays back quickly through lower annual heating bills, better energy performance, and increased market appeal, ideal for long-term landlords, property investors, and eco-conscious consumers.
How to choose the right insulation board
To choose the best board for your project, start with your property type, planned wall upgrade (internal or external), and performance targets:
- Check the required U-value and board thickness for compliance.
- Look for moisture and damp resistance if your walls are prone to condensation.
- Compare costs: EPS offers the best value, PIR and phenolic deliver higher performance at a higher price.
- For sustainability, mineral wool and recycled EPS boards are strong eco choices, great for those focused on green credentials.
Installation of wall insulation boards
Tools & preparation
You’ll need a sharp saw or utility knife for cutting; mechanical fixings or adhesives; protective clothing (including gloves, mask, and eye protection); and finishing materials designed for insulation (plasterboard, render, or cladding).
Step-by-step guide
- Measure and cut the boards to size.
- Fix boards to the wall with adhesive or mechanical fixings.
- Seal joints to prevent thermal bridging.
- Apply the chosen finish (render, plaster, or cladding).
Professional vs. DIY installation
While small DIY projects are possible, professional installation guarantees compliance with building regulations, best energy savings, and correct damp-proofing. This is especially important for landlords and housing associations meeting modern standards.
Wall insulation board prices
Average cost per m²
The average cost of wall insulation boards ranges from £10–£40 per m², depending on the material.
Cost by material type
- EPS: £10–£15 per m².
- PIR: £20–£30 per m².
- Phenolic: £25–£35 per m².
- Mineral wool: £20–£40 per m².
Long-term savings
Properly installed boards are estimated to cut energy bills by up to 35% and can save hundreds of pounds each year, depending on property size, fuel type, and current insulation. This makes them a smart choice for anyone keen to lower costs and add value.
Where to buy wall insulation boards
The easiest way to buy wall insulation boards is online or via specialist insulation suppliers. For the best value, impartial advice, and certified installation, consider getting a quote from trusted professionals, helpful for homeowners and landlords looking to future-proof their property.
Visit EcoInsulation.co.uk to compare products, get tailored recommendations, and arrange professional installation.
FAQs about wall insulation boards
Which thickness is best for cavity walls?
Typically, 50–100mm boards are used, but the exact thickness depends on the required U-value and cavity size.
Can I install insulation boards on old walls?
You can install insulation boards on older walls, but bear in mind that older solid walls may require additional preparation to prevent damp and ensure boards adhere properly.
Are insulation boards eco-friendly?
Some boards, such as mineral wool or recycled EPS, are eco-friendly, while others, like PIR and phenolic, have higher embodied energy but offer long-term energy savings.
Final thoughts
Wall insulation boards offer years of comfort, savings, and enhanced property value. Whether you’re upgrading a family home, developing rental stock, or aiming for government efficiency targets, there’s a board to match your project.