Floor and underfloor insulation

If your home has a ground floor, or if you live above an unheated space, underfloor insulation will help reduce heat loss.

Keeping the heat in is good for your wallet too. Floor insulation can save you around £110 a year on your energy bills.   

Read on to find out which type of floor insulation is right for your home. You can also check out our draught proofing guide for some easy, cost-effective ways to save money and warmth without lifting a single floorboard.   

Floor types 

The type of floor you have will determine what type of underfloor insulation you can put in. The most common floor types are: 

• Suspended timber 
• Solid 

The following sections will help you work out what type of floor you have, as well as how to insulate it.

What is a suspended timber floor?  

With a suspended timber floor, floorboards are fitted over wooden joists. You can picture the joists like the slats on a wooden bedframe. The floorboards sit on top of the frame, just like your mattress sits on top of the slats. Like your mattress, the floorboards are suspended above an empty space. 

What is a solid floor?  

A solid floor is usually made up of several layers. You can think of it like a solid bedframe, with no slats and no legs. There’s no empty space between the bedframe and the ground. The mattress is like the top layer of flooring, whether that’s carpet, tiles or laminate.  

How do I insulate a suspended timber floor? 

For insulating wooden floors, the easiest method is to insulate from below. If this isn’t possible, you’ll need to insulate from above. If you’re handy at DIY, you can save money by doing the timber floor insulation work yourself. 

Both methods involve putting insulation between the joists (wooden beams). You can do this using mineral wool or floor insulation boards.  

If you’re insulating from below, you would gain access via a cellar, basement, or hatch.  

If you’re insulating from above, you would need to take up the floorboards to get under the floor. 

If you can’t insulate from below but don’t want to take up the floorboards, a less disruptive option is to use an insulation robot. Companies such as Q-bot send a remote-controlled robot under the floor to spray foam insulation between the joists. The robot only needs a small access hatch to be cut in the floorboards. This avoids pulling up multiple boards so that a human can fit down into the crawl space.  

Solid floor insulation 

Floor insulation boards can be added either above or below the concrete or screed layer. 

Fitting the insulation on top of the concrete would slightly raise the level of floor. This means you may need to refit skirting boards and carry out some electrical work as well. You would also need to trim the bottom of your doors.  

Fitting insulation under a concrete floor slab or screed would involve replacing the entire floor. Floor insulation boards would be fitted on top to a damp proof membrane. This would be quite a big project, so you might want to combine it with installing underfloor heating. 

It’s important to note that if you are replacing your floor, building regulations require that the new floor is insulated.  

Underfloor insulation grant 

Homeowners in Scotland can get grant funding of up to £1,500 for underfloor insulation through the Home Energy Scotland Grant. An extra £500 is available as an interest free loan.  

To apply for an underfloor insulation grant, simply call Home Energy Scotland for free on 0808 808 2282. Their advisors will be able to help you through the process. You can also contact Home Energy Scotland through their online form.