Floor Insulation

What is

Floor Insulation

Whilst new homes incorporate insulation within the floor it’s very likely that an older property will not. And, when you bear in mind that some 10-20% of heat loss from a building can occur through poorly or uninsulated floors, it’s something that can make a considerable difference to energy efficiency.

There’s usually only a need to insulate the ground floor of a building or any floor that’s above an unheated room such as a garage.

There are two main types of floor – both of which can be insulated but in different ways.

  1. Older (pre-1930’s) prpoerties are likely to have a suspended timber floor which can be insulated, usually, by lifting the floor boards and adding insulation to the void below.
  2. Newer (post 1930’s) homes are likely to have a solid concrete floor which can be insulated by adding a layer of rigid insulation over the top of it.

You can expect annual savings of between £50 and £150 depending on your property. This may not seem significant compared with the cost but, when you consider the fact that it is maintenance free and designed to last it can represent excellent value for money.

floor insulation

Floor Insulation Example

Do I need to insulate all floors of a building?

Usually there’s only a requirement to insulate the ground floor of a building so if you live in an upper-floor flat then floor insulation is unlikely to be relevent or required.

You will not need to insulate the floors of the upper storeys of a house unless there is a floor which is immediately above a room / space that’s not heated such as a garage.

Can any type of floor be insulated?

In a nutshell – yes!

If you live in a relatively new house it’s likely that floor insulation has already been built in as it’s a requirement these days. If your property is a little older then there’s a very good chance of there being none.

It’s likely that your property will have one of two types of floor:

  1. Solid concrete floors:  Solid floors can be insulated by adding a layer of rigid foam insulation directly over the top before covering (typically with chipboard) and your chosen floor covering. Typically this insulation is going to need to be between 70mm and 150mm thick so you need to be aware that this is going to raise the floor level substantially.
  2. Suspended (wooden) floors: Often to be found in ollder, pre 1930’s properties suspended timber floors incorporate a void under the floorboards which can be insulated by simply lifting and laying nsulation (often mineral fibre) supported by netting between the joists. Technology is advancing all the time and certain spray foams are now available which means that floor boards don’t need to be lifted at all.

What insulation shoudl I use?

The answer depends on type of floor and your preference but the main types of insulation are as follows:

  1. Mineral wool / glass fibre slabs: Delivering excellent thermnal perfoprmance and being non-combustible makes this a great choice for insulating suspended timber floors. It’s light, can be cut and shaped easily and can be made to work with in uneaven areas too.
  2. Blanket insulation: This comes in rolls similar to loft insulation and can be used to very easily pack between joists in suspended floors.
  3. Rigid foam insulation: Can be used to insulate both suspended and concrete floors. A popular choice (especially when it comes to solid floors where it’s very easy to lay) with a wide variety of different types available.
  4. Spray foam insulation: Should only be installed by professionals but represents a great way to insulate a suspended floor without the need to remove floor boards. There’s even robotics available to make the process even more efficent!
  5. Multifoil insulation: Whilst more expensive its excellent thermal properties and a life expectancy of over 50 years makes multifoil insulation another great option for thermally upgrading both types of flooring.

What about ventilation?

If you have an older property with a suspended timber floor you should check for air or ventilation bricks on tyour outside walls. If you have any that are below floor level then these are required toprovide ventilation to the void under your floor and to stop your floorboards rotting.

For that reason they should NOT be blocked up.

Are there any regulations?

If you’re replacing at least half of your existing floor you are required to work to building regulations which, in England and Wales, means that the floor needs to achieve a minimum U-value (measure of the speed heat will travel through the floor) of 0.25 W/m2K.

For regulations in Northern Ireland or Scotland you should contact your local Building Control Office or Building Standards Department prior to works commencing.