How to Lay a Concrete Floor with Insulation

At the start of a project or extension, it’s important to think about limiting heat loss in your home with properly insulated flooring. Here we give our 4 easy-to-follow steps on exactly how to insulate a concrete floor. But keep these things in mind before you start:

  • Laying a concrete floor is a labour-intensive task that requires a few people to help with
  • Check that your building regulations allow you to make these changes

1. Ensure Your Floor is Level

Having your floors on a slope means that the insulation boards, once installed, are likely to be uneven and move around. This will result in a loss of insulation. Use screed and building sand to level off the area to be as flat as possible. You can use a laser level to check the correct levelling is achieved.

How to Lay a Concrete Floor with Insulation

2. Lay Your Damp-Proof Membrane

Once the floors are levelled properly, you can lay the damn-proof membrane (DPM) over your sand layer to ensure the insulation isn’t punctured by the concrete stones. It might be easier to apply an entire sheet to your area, but if it isn’t possible, make sure the DPM edges overlap by about 150mm. This will make sure no moisture seeps into the concrete. 

3. Add Your Insulation

While it is possible to insulate after pouring your concrete (above the concrete) we recommend insulating below the concrete layer. This allows the concrete slabs to actually absorb the heat too, which makes overheating unlikely and is our preferred method of concrete insulation.

The most common insulation sheets are 4 metre sheets. If you can’t cover the whole area with one sheet, you can lay more but make sure you fill any gaps with foam and tape the sheets down to avoid moisture seeping into the concrete.

Add your insulation on top of the DPM and around the edges of the surface, and then it’s time to pour the concrete.

4. Concreting

There are several options for concreting your surface. Though it can be a lot of work, if you have a small surface area it is possible for you to barrow it in manually.

The most straightforward solution is getting ready-mixed concrete pumped directly into the flooring. 100-130mm is the recommended amount, and once it’s laid you should wait 3-4 days for the concrete to adjust to the temperature and moisture of the room.

For structures like a garage, you’ll need to reinforce your concrete. Rods, bars or mesh are recommended for this.

How to Lay a Concrete Floor with Insulation

Once your concrete has settled, it’s time to lay your flooring of choice (tiles, floorboards etc.) with the peace of mind that your room will be properly insulated!

Longley Concrete are experts in concrete floor insulation. If your job is bigger than just a “DIY” project, then get in touch and our experts will be on hand to help spec out and get the perfect fitted insulation for your project.