Underfloor Insulation

Underfloor insulation is built to fit beneath floorboards or concrete floors to prevent heat loss and reduce draughts.

What Is Underfloor Insulation?

Underfloor insulation is a specialised solution designed to trap heat inside the home. It is made using various materials, including reflective foil, mineral wool and rigid foam boards. The insulation material should be matched to the floor type to ensure maximum effectiveness.

What Is Underfloor Insulation Used For?

You can use underfloor insulation boards on different floor systems:

• In new concrete floor builds, position the insulation under the slab. Or lay it on top of the existing slab if installing new flooring.
• Fit the insulation boards between joists in timber floors.
• Position it under laminate and engineered wood flooring. Ensure the insulation is compatible with floating floors to maintain stability.
• Install it beneath tiled and stone floors. Normally installed beneath the screed layer when used with stone or tiled floors.
• Install it under suspended, cellar and basement floors.

Types of Insulation for Underfloor

Insulation for underfloor use comes in many forms. It includes:

Insulation Slabs

Usually made from mineral or glass wool, these slabs can be cut to fit between joists.

Reflective Foil Insulation

Foil reflective insulation models SF19+, SF40 and SFUF are typically used in suspended timber floors or underfloor heating systems to reflect radiant heat upward.

Insulation Boards

Rigid underfloor board insulation is ideal for solid floors, such as concrete or stone. It is available in different materials and performance levels. The most common boards for underfloor insulation are:

• PIR boards: These are lightweight, high-performance panels with remarkable insulation performance. They are perfect for tight spaces.
• EPS/XPS boards: These are durable polystyrene boards suitable for a wide variety of floor systems.
• Specialist boards: Ultra-thin boards like OPTIM-R deliver high insulation performance with minimal thickness. Best for areas with limited floor height.

Benefits of Underfloor Boards / Slabs

Here is why investing in underfloor insulation slabs is a good idea:

• They are an effective way to stop downward heat loss.
• Reduced heat loss means lower heating costs and more savings.
• They minimise underfloor draughts.
• They help reduce noise between floors.
• Most underfloor boards are designed to last, so you won’t need frequent replacements.

Why Choose Our Underfloor Insulation?

We only sell quality underfloor insulation boards. That means we are selective about the brands we carry and stock only trusted names with a proven performance record.

Our underfloor boards are engineered to meet or exceed UK Building Regulations for thermal performance.

Get the right underfloor insulation for a warmer, more efficient build. Shop trusted UK brands delivered straight to your site.

FAQ

Can underfloor insulation cause damp?

Only if installed incorrectly. Always pair underfloor insulation with proper damp-proofing and adequate ventilation to prevent moisture buildup. When fitted as recommended, underfloor insulation keeps your floors warm without causing damp issues.

How to install underfloor insulation

For timber floors, fix the panels tightly between joists. For concrete or solid floors, lay the boards over the surface or under a screed. The insulation should be flush, with no gaps. Include any required damp-proof membranes as specified by Building Regulations.

What is underfloor insulation?

This is an insulation material specially designed for installation under floors. It is effective in reducing draughts and minimising heat loss. The specific underfloor insulation slab to use depends on the type of floor.

Which underfloor insulation is best?

The best underfloor insulation depends on your floor structure and project goals because what works for one floor may not suit another. For example, mineral wool boards work best on timber floors, and rigid insulation boards work great on concrete floors. So always consider the floor type first.