100mm Celotex GA4100 PIR Insulation Board — High Performance Thermal Insulation

When it comes to achieving excellent thermal efficiency in your home or commercial property, the 100mm Celotex GA4100 PIR insulation board remains one of the most trusted and effective insulation products in the UK.

Lightweight, easy to install, and delivering outstanding thermal performance, this multi-purpose insulation board is a go-to solution for architects, contractors, and DIY homeowners looking to improve energy efficiency without sacrificing space.

What Is 100mm Celotex GA4100?

Celotex GA4100 is part of the Celotex GA4000 range of high-performance polyisocyanurate (PIR) insulation boards.

The “GA” stands for “General Application”, meaning this board can be used across a wide range of projects — including floors, walls, pitched roofs, and flat roofs.

Each board is 100mm thick, providing a strong balance between thermal performance, rigidity, and ease of handling.

The core is a rigid PIR foam, faced on both sides with a low-emissivity foil, designed to reflect radiant heat and enhance energy efficiency.

100mm Celotex GA4100 Specifications

This combination of low thermal conductivity and high compressive strength makes GA4100 ideal for both new builds and retrofit projects.

Where Can You Use Celotex GA4100 100mm?

Because of its multi-purpose design, 100mm Celotex GA4100 is suitable for almost any part of the building envelope:

1. Roof Insulation

• Can be installed between or under rafters in pitched roofs.

• Ideal for flat roof applications beneath waterproofing layers.

• Helps prevent heat loss through the roof — one of the main causes of wasted energy.

2. Wall Insulation

• Excellent for solid masonry or timber frame walls.

• When used internally, it helps achieve Building Regulation U-values with minimal thickness.

3. Floor Insulation

• Perfect for solid concrete or suspended timber floors.

• Provides a stable, moisture-resistant thermal layer under screeds or floor finishes.

Thermal Performance & Energy Efficiency

The 100mm Celotex GA4100 delivers a λ-value of 0.022 W/m·K, meaning it’s one of the most efficient insulation boards per millimetre of thickness on the market.

When used correctly, it can help achieve U-values as low as 0.18 W/m²K, significantly reducing heat loss and improving EPC ratings.

That translates directly into:

• Lower heating bills

• Reduced carbon emissions

• A warmer, more comfortable home all year round

Key Benefits of 100mm Celotex GA4100

✅ Outstanding Thermal Efficiency — Reduces energy loss and boosts building performance.
✅ Multi-Purpose Application — Suitable for floors, roofs, and walls.
✅ Lightweight & Easy to Cut — Easy handling reduces installation time and labour costs.
✅ Durable & Moisture Resistant — Rigid PIR core prevents water absorption.
✅ Eco-Friendly Manufacturing — Made with low GWP blowing agents, zero ODP.
✅ Fully Certified — Backed by BBA, CE, and UKCA marks for building compliance.

Installation Tips for Celotex GA4100 100mm

Getting the most out of your insulation depends on proper installation. Here are some expert tips:

1. Cut accurately using a fine-tooth saw or sharp knife.

2. Fix boards tightly together to avoid air gaps.

3. Seal all joints with foil tape to improve airtightness.

4. Ensure vapour control in moisture-prone areas.

5. Follow Celotex datasheet guidelines for fixings and spacing.

These steps ensure the insulation performs as intended — maintaining high energy efficiency over the life of your building.

Sustainability & Compliance

The Celotex GA4100 range is manufactured under an ISO 14001:2015 certified environmental management system, supporting sustainable construction practices.

• ✅ Zero Ozone Depletion Potential (ODP)

• ✅ Low Global Warming Potential (GWP)

• ✅ A+ rating in the BRE Green Guide

• ✅ BBA Certificate 95/3197

Celotex insulation is trusted across the UK for meeting Part L of Building Regulations and SAP requirements for energy efficiency.

Summary: Why Choose 100mm Celotex GA4100?

If you’re looking for a reliable, high-performance insulation board that meets modern energy standards while being lightweight, easy to handle, and environmentally responsible — 100mm Celotex GA4100 is the smart choice.

In short:

• High-performance PIR insulation (λ = 0.022 W/m·K)

• Versatile for walls, floors, and roofs

• BBA certified and fully compliant

• Reduces heating costs and improves comfort

• Manufactured to the highest environmental standards

PIR Insulation Boards

The Celotex range of PIR insulation boards provides thermal insulation solutions that fully meet the requirements of current legislation including Part L, BREEAM and the Code for Sustainable Homes, as well as the demands of building professionals, specifiers and users. These high performance insulation solutions are represented in our depth of product offering. Please note : Due to recent national shortages of PIR insulation, We now offer Celotex, Ecotherm, Recticel and Iko to help to offer a speedy delivery. You may be offered an alternative brand due to local stock availability.