How to Insulate a Roof Using PIR Insulation Boards Gfi: Ultimate Thermal Efficiency Guide

Steven Aug 11, 2026

How to Insulate a Roof Using PIR Insulation Boards

Glass Tissue Faced Insulation
Glass Tissue Faced Insulation

Learn how to insulate a PIR roof step-by-step using durable PIR insulation boards to boost energy efficiency and comfort.

Polyiso Insulation Rigid Boards
Polyiso Insulation Rigid Boards

Many people under estimate the costs and work involved when insulating, in this video I demonstrate how we insulate using solid insulation boards otherwise known as PIR .

PIR Insulation Board Roof Installation Guide

Customized Rigid Polyisocyanurate Insulation Foam Board
Customized Rigid Polyisocyanurate Insulation Foam Board

Professional guide for PU/ PIR roof insulation systems. Learn how PU/ PIR insulation boards are installed on steel structure and lightweight roofs .

Transform your property's thermal performance with expert PIR insulation installation techniques using premium brands like Celotex, Recticel, and Ecotherm When it comes to achieving exceptional thermal performance in your building project, few materials deliver the combination of efficiency, versatility, and ease of installation that PIR (Polyisocyanurate) insulation boards provide. Whether ...

PIR Sandwich Panels Composite Sandwich Panels
PIR Sandwich Panels Composite Sandwich Panels

Insulating a pitched roof at the ceiling

Insulating a pitched roof at ceiling level is a cost-effective way of installing roof insulation where the attic space will not be used as a living area. Excellent thermal performance can be achieved by using Mannok's Therm Roof PIR insulation boards at ceiling level.

This rigid foam board insulation is engineered to deliver excellent thermal resistance while being easy to install and long-lasting. Whether you're insulating a roof , wall, or duct system, our PIR insulation board is designed to improve energy efficiency and maintain indoor comfort.

Kingspan Thermaroof TR27 Flat Roof PIR Insulation Board
Kingspan Thermaroof TR27 Flat Roof PIR Insulation Board

How to insulate over rafters. Over boarding insulation. Cut and fit PIR ...

In this video I show you a step by step guide of how to overboard (rafters with insulation ( PIR ) board . I show how to measure, cut, fix, foam and tape the boards and show you the tools and ...

Insulating a pitched roof between and below the rafters is a very common roof insulation choice, particularly for retrofit and refurbishment projects. For this method of pitched roof insulation , we recommend using Mannok's Therm Roof Insulation boards between the rafters and Mannok's Therm Laminate-Kraft Insulation boards below the rafters.

Floor Insulation Pir Boards
Floor Insulation Pir Boards

Installing PIR boards in Rafters

Why do you want to put PIR against the rafters? You've effectively trying to convert a cold (ventilated) roof into a warm roof and that's not trivial. To achieve beneficial insulation for the house it's going to be far more cost effective and safe (for the fabric of the roof ) to simply add insulation to the floor of the loft.

CNZ Insulation Board High Performance PIR Insulation Made in New
CNZ Insulation Board High Performance PIR Insulation Made in New
75mm Unilin FR ALU High Performance PIR Board pack of 4
75mm Unilin FR ALU High Performance PIR Board pack of 4
Comprehensive Guide to Foam PIR Insulation R Value GFI
Comprehensive Guide to Foam PIR Insulation R Value GFI
How to Insulate a Roof Using PIR Insulation Boards GFI
How to Insulate a Roof Using PIR Insulation Boards GFI
Extruded Polystyrene vs Expanded Polystyrene vs Polyisocyanurate
Extruded Polystyrene vs Expanded Polystyrene vs Polyisocyanurate
Cold Insulation Material PIR Pipe Polyisocyanurate Foam
Cold Insulation Material PIR Pipe Polyisocyanurate Foam
Insulation Materials Insulation Advice
Insulation Materials Insulation Advice
PIR insulation board panel sheet for wall insulation with excellent
PIR insulation board panel sheet for wall insulation with excellent
ASTM C591 PIR Foam Pipe Insulation for Cold Applications
ASTM C591 PIR Foam Pipe Insulation for Cold Applications

Download here our 'Everything about installing PIR insulation on a flat roof' guide A roof structure is a system whereby a correctly-fitted insulation layer plays a crucial role in achieving the required thermal and mechanical performance. Find out everything you need to know in our guide!