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Ground to floor solutions and effective concrete floor insulation prevent unnecessary heat loss in buildings. They can help to maintain a comfortable temperature and improve energy efficiency. 

Without under slab insulation, the direct contact from the floor to the ground makes it an easy route for winter cold to get in. 

Insulation can be installed above or under concrete slabs to improve thermal efficiency, with around 30 percent of all heat in homes lost through the floor.  

Why do we need ground to floor insulation?

Concrete slab insulation between the ground and the floor is vital to create a comfortable living environment. Not only does it make a building more energy efficient, it also helps to create cosy, comfortable and habitable conditions for people living or working there. 


Some of the main benefits of under slab insulation include:

  • Energy efficiency – helps to trap heat in and reduce energy bills substantially.
  • Fire safety – ROCKWOOL stone wool insulation can withstand temperatures in excess of 1000 degrees1

  • Sustainability – solid floor insulation lasts for the lifetime of your building.

Calculator and savings

Costs and savings will vary depending on several different factors. But the initial cost of insulation will be outweighed by the savings made over time on energy bills. 

Installing concrete floor insulation can significantly reduce heating costs over a building’s lifetime. The slabs can also be used again in other projects if the building is demolished, making them an investment for future projects. 

Concrete insulation can be placed either beneath or above a ground bearing slab. Calculating the size of the surface area will directly provide the m2 needed. The m2 measurement of floor equals the m2 of insulation required.

Use the ROCKWOOL U-value calculator to help determine the ground floor insulation type and thickness required. 

Construction Site: Neat Clean Crawlspace, Floor Joists, and Pony Wall - crawl space design and installation process
A well-insulated floor contributes to the comfort in a building, keeping the floor temperature at a steady level.

Roger Peeters

ROCKWOOL Group Product Manager
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Renovation Case Studies

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Financial support

Check the Energy Savings Trust website to see whether there are any financial support schemes available for concrete floor insulation.

Energy Efficiency, Key, Keyboard, Button



How much ground to floor insulation will I need?

To calculate how much insulation you’ll need, use our U-value calculator.

It’s important to note that ROCKWOOL concrete floor insulation should not be used under groundwater level.

Does floor insulation make a difference?

Floor insulation can make a significant difference to the temperature in buildings – and contributes to savings on energy bills over time.

Can I use ROCKWOOL insulation under a concrete slab/floor?

ROCKWOOL insulation can be applied under a concrete slab/floor for different purposes. It can be used under the ground floor slab directly placed on the ground, it can be fixed underneath a basement or car park soffit  with visual requirements – or below an intermediate floor with a separate ceiling finish. Please contact your local ROCKWOOL office for more detailed information.