Flat roof insulation is crucial for improving energy efficiency, comfort and living standards in buildings. In an uninsulated home, up to 25% of heat is lost through the roof.1

We offer a versatile range of premium-quality stone wool roof products – providing excellent thermal, acoustic and fire-resistant solutions for both commercial and domestic projects.


Flat Roof Insulation Products

Why do we need flat roof insulation?

As heat normally rises, most energy loss is usually through the roofing area. Flat roof insulation is an essential measure that can enhance the energy efficiency of a building and reduce fuel costs. 

Creating more effective flat roof barriers also offers you protection from the unpredictable outdoor climate, including overheating in summer conditions, rain and snow. 

From high rise apartment blocks to residential designs, from industrial units and large commercial facilities to schools and hospitals, flat roofs are an integral part of a modern building design. 

Indeed, terraces, rooftop gardens, blue roofing, water retention and solar usage are becoming ever more popular, with the trend for functional roof spaces bringing more value to the users and owners of buildings.

Flat roofs are the umbrella generating spaces to live and work.

Kim Brandt

ROCKWOOL Group Product Manager

Calculator and savings

Flat roof insulation is very cost competitive when saving energy consumption overall – and provides a key, valuable investment for the future. 

In addition to this, it often has a relatively fast payback time in terms of money, energy and carbon footprint. 

There is no ‘one size fits all’ answer to how much you will require. Since there is usually no limitation to the installation height on a roof, and ‘the sky is the limit’ so to speak, insulation thickness can be adjusted to almost any possible customer specification.

The average installed density of stone wool flat roof insulation globally is around 90 – 160 Kg/m3.

Use our U-value calculator to work out the potential energy savings you could make. Also 

To simplify the specification of flat roof insulation, ROCKWOOL has launched a new Flat Roof Zoning Tool. This online Flat Roof Zoning Tool helps specifiers optimise insulation design by zoning flat roofs according to how each area will be used. 

Roof Zoning Tool
ROCKWOOL solutions for flat roofs are durable and proven by more than 40 years of use. ROCKWOOL flat roof insulation is also non-combustible and will protect you, your building and inventory if a fire occurs.

Kim Brandt

Kim Brandt, Global Product Manager, ROCKWOOL

Case Studies


The project

To achieve the very best performance demands commitment, skill, and passion. The team behind the recent reinvention of the Royal Academy of Music in Regent’s Park, London called on all three qualities in creating stunningly beautiful, acoustically brilliant and inspiring spaces for staff and students.


The problem

Creating impeccable acoustic environments and ensuring control not only of how sound travelled around the spaces as well as ensuring effective isolation from other spaces within the building proved a key challenge of the project.


The solution

In order to complement the structure of the building and ensure each space was acoustically isolated, All Metal Roofing specified insulation from ROCKWOOL for the Royal Academy of Music project.

Read more about The Royal Academy of Music here



Royal Academy of Music, Building, Leisure, HARDROCK Multi-fix (DD), RWA45
We knew we could trust the ROCKWOOL insulation for its performance and acoustics properties.

Richard Shanahan

All Metal Roofing
To be updated
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Flat Roof Acoustic Reference Guide

Download our guides

Financial support

The Energy Savings Trust is a great source of advice on financial support schemes available for roof insulation.

Energy Efficiency, Key, Keyboard, Button


How thick should flat roof insulation be?
Do you need to ventilate a warm flat roof?
What is a cold flat roof?