Floor Insulation

What do you need to know about Floor Insulation?

Floor insulation refers to insulation placed beneath the floorboards. The primary purpose is to reduce heat loss, as up to 20% of heat can escape through the floor into the ground

In addition to the floor, you will also need to insulate the gaps between the floor and skirting boards as well. This is helpful in reducing draughts.

Obviously the best time to install floor insulation is while a new floor is put into place, even though floors can also be retrofitted with insulation. Not only will this reduce heat escaping but also save a large amount on your heating bill.

Should the floor be insulated?

Usually, people focus on insulating attics and exterior walls. Although it is important to insulate these areas, you can save a lot of money on your heating costs if you insulate your floors as well.

Basement floor insulation or underfloor insulation takes many different forms. And, if your house does not have basements and unheated cellars, then floor insulation will further reduce your overall energy bill.

The first reason is that it will help getting rid of drafts from your house. Not only will it prevent drafts from penetrating through the gaps between the floor and the ground but it will also reduce heat escaping from them. In this regard, we recommend installing rigid insulation panels, particularly between the floor joists.

If you have wooden floors, they can get deteriorated or damaged due to the accumulation of moisture. This can be avoided by putting a layer of insulation between the crawl space and the floor – in order to create a vapor barrier, which will prevent moisture from soaking your wooden floor.

Solid Floor insulation can also provide extra protection to the piping system beneath the floors during cold winters.

Because pipes are placed under the floor, an insulated floor can significantly lower the risks of pipe bursting during the winter season.

Benefits of Floor Insulation

Just by filling the gaps between the floor and skirting boards, you can save between £25 to £30 pounds per year.

In addition, with floor insulation you can reduce your carbon footprint up to 240kg per year and 100kg when you opt to fill the gaps between the skirting boards and floor.

By slowing down the movement of heat, your house will stay warmer for longer during winter and cooler in the summer months.

The underfloor insulation for wooden floors can save you about £60 pounds per year. This means recouping the cost within 2 years.

Keep in mind when installing your floor insulation

Whether you get a contractor or you plan to do the work yourself, the existing floorboards, carpets and furniture will have to be removed. This is a good time to check for signs of dampness or moisture and apply the necessary fixes.

So allow some budget to carry out the additional work if necessary.

Budget your Floor Insulation

Regardless of the size of your floors, the cost of hiring a professional shouldn’t vary too much. Unless your house screams “I’m rich, look at my big floors!” you shouldn't be in for a big surprise.

• Professional installation: roughly from £800 to £1000 to hire a contractor.
• Do it yourself: the cost of materials is around £150 for an average house including the material for skirting boards & gaps to fill.

Put a £100 aside in case your underfloor needs some TLC.

Type of insulation for your floors

You have many options to choose from, but we will just mention the most popular ones.

• Blanket insulation (rolls or batts)
• Mineral Wool
• Foam Board
• Rigid board

What is the minimum thickness for floor insulation?

According to UK building regulations, the thickness differs according to the type of floor, the shape, size, and construction. However, the minimum thickness is 150mm for mineral wool and about 90 mm for rigid foam insulation. Whatever you choose you need to achieve a U value of 0.25.

Most builders will opt for rigid foam insulation between the floor joist as you can fit them tightly and ensure no gaps are left.

What kind of insulation for suspended floors?

If you want to insulate the area between the crawl space and the floor joists, it is best to choose a breathable insulation such as fiberglass or mineral wool with a breather membrane on the cold side to reduce drafts and a vapour barrier on the warm side (above). Make sure you have good subfloor ventilation, the airflow between the ground and the timber joists is necessary to avoid dampness and rot. However this airflow can increase draughts if the floor is not properly insulated. Making sure your contractor gets the ventilation right will be key to the success of your insulation. So don’t hesitate to ask those questions, and contact previous customers as well, as plenty can go wrong with floor insulation.

Can I insulate on top of floorboards?

The simple answer to this question is “Yes,” you can insulate on top of floorboards. Usually a damp proof membrane is laid out before installing rigid foam boards.

However, you need to understand that the insulation can be done at the time of replacing the floorboards. This can likewise be done if you have rigid floor insulation on the top.

In the UK, in some old homes, you will find suspended timber floors – and the insulation of such floors is usually done when you lift the floorboards and lay the insulation material between the joists. The best insulation material for timber floors is mineral wool insulation.

Do I need insulation between floors?

In general, you don’t need to insulate between the floors. You only need the insulation of the ground floor. Also, you don’t need insulation of your floor space if you live on the upper floor.