Floor Insulation Guide

Floor Insulation Guide
Posted in: Guides, Insulation

Insulating your floorboards can help to reduce your energy bills and ensure that your home stays warm and draught free. Most people insulate the ground floor of their property because this is where you’ll feel the cold. You can also insulate an upper floor if it isn’t above a space that has no heating such as a garage or a porch. Read on for more information about whether to insulate your floor as well as the method, costs and advantages involved.

Floor Insulation

Do I Need to Insulate My Floor?

Your floors can lose around 15% of the heat in your home and so by insulating them you can save on average around £60 a year. The work will pay for itself within two or three years depending on whether you do the job yourself or get a professional insulation company to do it for you.


How Can I Tell What Type of Floor I’ve Got?

It’s likely that if your house was built before the 1930s you will have a suspended timber floor with joists and floorboards. One way you can tell is if you have air bricks on the outside of your house. Another way is by simply lifting the carpet to see if you have floorboards.

If you have flooring which you are unable to look underneath, there is still another alternative if you have a basement. Go down into the basement and look up to see if you have wooden joists with floorboards above them. If your house was built after the 1930s then it will probably have a solid floor and you’ll be able to see this by lifting a piece of carpet in the corner of a room.

Again, if you go down to the basement, the absence of joists will indicate you have a solid floor. If the ceiling has been covered with plasterboard a small section will need to be removed in order to confirm whether there are joists present or not.


What Are the Different Types of Floor Insulation?

There are different types of floor insulation for solid and suspended floors. Suspended floors tend to lose more heat than solid floors. However, a solid floor does still lose heat and it can be very beneficial to insulate it.

Suspended Wooden Floor Insulation

If you don’t have a basement then you will need to lift the floorboards to lay the insulation. You can use a soft material like mineral or sheep’s wool to insulate between the joists and then add wood fibre boards to keep everything in place.

If you have a basement, the insulation can be installed between the joists and then battens can then be put underneath the joists to add more insulation. This can be kept in place with netting. It is essential to make sure that any holes that have been caused by old or existing pipework or cables are sealed to prevent draughts getting through.

Solid Floor Insulation

If you are insulating an existing concrete floor, then insulation can be added over the top of the floor. If the solid floor is being removed or the project is a new build then it is possible to insulate beneath the solid floor.

Don’t forget that if you apply insulation over the top of your floor, it may be necessary to adjust the doors and any floor level electrical sockets. The best material to use for over floor insulation is foam boards because they are easier to lay, and you don’t need a great deal of thickness to achieve the right amount of insulation. Before you place the foam boards on the floor a damp proof membrane will need to be laid to protect the floor from moisture penetration.

Underfloor insulation should begin with the layer of sand insulation with a damp proof membrane installed on top. After this stage is completed, insulation boards can then be laid, and the new concrete poured on top.


Can I Install Floor Insulation Myself?

Insulating a wooden floor can be taken on by anyone with some DIY experience. All the materials you need are available at DIY stores and the sales staff should be able to help you if you have any questions.

The work is simpler than dealing with a solid floor because it doesn’t involve other work such as adjusting doors and re-positioning electrical sockets. If you are not confident enough to take on this job yourself, then get a professional who will know exactly what type of materials would be best suited for a satisfactory insulation.


How Much Does Installing Insulation Cost?

If you install the insulation yourself, the costs will obviously less because of the saving you make on professional labour charges. You can insulate a suspended timber floor in an average sized room for around £100. If the job is undertaken by a professional, it will probably cost at least double this amount. If you are having a solid floor installed by a professional, the cost will normally start at around £900 for an average sized room.


Types of Floor Insulation Material

The following materials are commonly used as underfloor insulation solutions:

  • Rock Mineral Wool


Blanket (batts and rolls) are the cheapest with foam boards being the most expensive. If you want an environmentally friendly option, then go for sheep’s wool which is 100% natural. It’s soft and light, it absorbs water and it won’t cause any irritation to your throat or your skin when you are installing it.


Is There a Guarantee if You Have the Work Carried Out Professionally?

Normally if you are dealing with a reputable company they will offer you a warranty of around ten years, but warranties do vary from company to company.


How Thick Should My Underfloor Insulation Be?

The thickness of the insulation will vary depending on the type of floor that you have and building regulations in your area. In England or Wales, the floor should have a U-value of 0.25W/m2K or less, meaning that you’ll probably need at least 70mm of foam insulation or around 150mm of mineral wool. This may change depending on the type and size of your floor. 


How Much Difference Does Floor Insulation Make?

Installing floor insulation into the key rooms in your home is crucial in keeping the house at an acceptable temperature all year around. On average, installing underfloor heating reduces heat loss through the floor by 79%, and can also reduce cold draughts throughout the entire house by 30%.

What Are The Benefits Of Floor Insulation?

1. Save Money On Your Heating Bill

Installing floor insulation can help you rely a lot less on heating your house up. According to The Energy Saving Trust, homeowners could save up to £75 per year on their heating bill, which will certainly add up over time. Letting less heat escape through the floor will give your boiler, and your wallet, a much-needed break.  

2. Make Your Home Warmer

Having floor insulation in your home can also mean that many draughts that can spread chills through the home are reduced, thus making your home warmer and more enjoyable to live in throughout the colder winter months. 

3. No Maintenance Once It’s Been Installed

Once you’ve installed floor insulation, there is no extra maintenance needed, you can just enjoy the benefits. 

4. Future Proof Your Home

While newer build houses tend to have floor insulation built-in, a lot of older style houses were not fitted with floor insulation at the time. By adding the insulation yourself, you can help add value to your home and bring it in line with more modern buildings. It can also improve the energy efficiency of your home, and improve your EPC rating.

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