Roof Insulation Board

Roof insulation boards are often fixed across flat roof systems, above rafters, or below ceilings. They help meet UK Building Regulations and enhance thermal performance when installed correctly.

What Is The Roof Insulation Board?

Roof insulation boards are rigid thermal panels that boost a roof’s energy performance and structural stability. They are commonly made from materials such as PIR (polyisocyanurate), XPS, or EPS foam and provide reliable thermal resistance. They are also known for their compressive strength and long-term weather resistance.

They can be installed beneath tiles as sarking boards, above roof decks as roofing boards, or internally as ceiling insulation boards.

What is Roof Insulation Board Used For?

Roof insulation boards can be installed across various roofing systems, depending on the project type and energy goals. They are widely used for:

• Pitched roofs: Installed as sarking board above rafters to minimise heat escape and condensation.
• Flat roofs: Used as flat roof insulation boards beneath waterproof membranes to enhance thermal performance.
• Loft, attic, and garage ceilings: These are installed between or under joists as ceiling insulation boards to improve indoor warmth.
• Over-rafter systems: Used externally as continuous roof insulation panels to eliminate thermal bridging.
• Refurbishment and conversions: Ideal for upgrading older roofs to meet current Part L energy efficiency standards.

Types of Roof Insulation Board

Insulation Wholesale offers insulation boards for roofs that are suitable for every project. Choose from:

• PIR Roof Insulation Boards: These are high-performance boards with superior thermal conductivity and compressive strength. All types can be used with vapour control layers and compatible waterproofing membranes where required.
• XPS Roof Insulation Boards: Moisture-resistant and durable. Ideal for inverted and flat roof installations.
• EPS Roof Insulation Boards: Light and cost-effective, with good thermal efficiency.

Benefits of Roof Insulation Board

A well-insulated roof helps increase long-term comfort and energy savings for buildings. This is why roof insulation panels are a must-have for modern builds and refurbishments:

• Reduce heat loss: They keep warmth inside during winter and deflect heat in summer.
• Enhance building efficiency: They improve U-values to help meet Part L Building Regulations.
• Perfect for flat and pitched roofs: They work equally well under tiles, membranes, and metal sheeting.
• Moisture and mould protection: XPS and PIR variants resist water absorption and condensation. They are particularly effective when combined with vapour control layers.
• Improve structural performance: They add rigidity to roof decks and help distribute loads evenly when used within approved assemblies.

Why Choose Our Roof Insulation Board?

Here’s what makes Insulation Wholesale the trusted choice for roof insulation boards in the UK:

• A comprehensive range of roof insulation sheets and flat roof insulation boards.
• Products from leading brands known for reliability and thermal performance.
• Solutions for new builds, refurbishments, and under-deck insulation systems.
• Expert advice to help you select the right roofing board for your project.
• Trade pricing, bulk savings, and fast nationwide delivery to the site or home.

Keep your building warm and compliant with our premium flat roof insulation panels. Shop now for fast UK delivery and proven thermal performance.

FAQ

What thickness insulation board for roof?

Roof insulation thickness depends on the type of roof and the target U-value. Typically, both pitched and flat roofs need 100–150 mm boards to achieve modern thermal performance standards.

How to install foam board insulation on roof?

For over-rafter installations:

1. Step: Fix the roof foam board insulation directly to the rafters using mechanical fasteners.
2. Step: Seal joints with foil tape.
3. Step: Install counter battens.
4. Step: Fit the roof covering.

Always check manufacturer guidance for fixing and vapour control requirements.

How to install insulation board on flat roof?

1. Step: Lay flat roof insulation boards on the roof deck, ensuring a clean and dry surface.
2. Step: Tightly butt, stagger, and secure the boards with appropriate fixings or adhesive.
3. Step: Apply a waterproof membrane over the insulation.

For inverted roofs, install above the membrane with protection layers as per design.

What is the minimum insulation for a flat roof?

To meet UK Building Regulations, a flat roof typically requires a U-value of 0.18 W/m²K. Depending on the insulant’s conductivity, this often equates to around 120 mm PIR board.