The best ways to insulate your floor

19 November 2019

Paying too much for your energy bills? Is your house cold and draughty?

Have you already installed some form of insulation, but it just hasn’t made your cold home warmer?

Insulating your floor may be the logical next step. Suspended timber floors let in cold air, dust and mould from the void below, creating cold draughts and uneven temperatures.

By warming cold surfaces, floor insulation is the cosiest and best way to stay warm in winter, and comfortable all year round.

So leave the hot water bottles and onesies behind and make the long-term investment in warming your home!

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Heat loss through floor boards

 

What kinds of flooring are there and what type of floor can you insulate?

The most common type of flooring in the UK is a suspended timber floor, usually found in older homes. A suspended timber floor leaves a crawl space, or void, underneath your floor boards for draughts to pass through. An air vent on the outer wall of the void keeps the crawl space ventilated to reduce the risk of low-level damp, but also often causes draughts and cold air to come through the floorboards, and affect the comfort in the home.

Solid concrete floors are found in most modern properties. Solid floors are generally warmer than suspended floors and cannot be insulated from underneath. Any insulation, if needed, will have to go on top of the concrete slab.

 

Why do so few property owners insulate their floor?

In the UK, only 3% of suspended floors have been insulated, even though uninsulated timber floors contribute to as much as a quarter of the total heat loss for a typical home! 

Generally, traditional methods of floor insulation are disruptive and extremely costly, meaning that people tend to prefer other methods of insulating their home,  over floor insulation.

However, there are some ways around this cost and disruption. 

Have a read to find out what your options for insulating the floor in your home are, and how to make your cold home warmer.

 

Cover your floorboards for improved comfort

One common method of reducing draughts from the floor is to cover it up. You can do this by installing carpet with underlay, a thin layer of cushioning that provides some reduction in sound, moisture and draughts entering the home. Another option is to install vinyl flooring, a plastic material in the form of vinyl floor tiles, vinyl planks or vinyl sheets. It’s easy to install, durable and can be combined with carpet and underlay. However, covering your floorboards can be disruptive and costly, as it involves removing furniture, fittings, and requires redecoration. For example, skirting boards, fitted cupboards and radiators may have to be moved, and the bottom of your doors may have to be cut back. On top of that, it is shown to have limited impact on draughts and thermal losses.

 

Replace your floor with concrete for a long-term warmth

Another method is to retrofit your home by replacing the floor altogether, installing a solid aggregate and concrete floor like those in modern houses. This is usually the most sensible long-term solution for homes that have very low voids of less than 150mm deep, or if you’re doing a major or whole house retrofit. A damp proof membrane (DPM), typically a polyethylene sheet, is laid under the concrete and prevents the risk of moisture rising through the floor. This option can save you a lot of money on your energy bills in the long-run, but is expensive and disruptive to install.

 

Fill the void or crawl space under your floor with insulation

Instead of replacing the floor, can’t you just fill the void with insulation, for instance polystyrene beads? This option is not recommended as it blocks the vents, preventing the flow of ventilation under the floor, causing moisture to build up, and potentially causing more serious, long-term problems with damp and mould. In extreme cases, this can result in deterioration of the joists and any covering above, giving you much bigger problems to deal with! Not only is it difficult to access the void to install the insulation, but this method also requires a lot of material, which increases the cost and time of installation.

 

Fit insulation panels under your floor by hand 

Fitting insulation panels by hand can take between one to two weeks. It requires the floorboards to be lifted, insulation panels and an airtight membrane to be cut to shape and installed, and then everything to be put back together and redecorated. This option is very labour intensive, expensive and disruptive. Poor installation can also lead to gaps between panels creating potential thermal bridges, and areas where draughts can still penetrate the floor. Poor installation can also overly-compress the insulation, reducing its performance, or allow it to sag, creating pockets of unwanted air between the insulation and the floor boards. Achieving good quality is key but is time consuming and takes skilled labour and oversight to ensure. 

 

Install underfloor heating to warm your floor

For a big improvement in comfort, you can install underfloor heating. Underfloor heating works by using electrical heating elements or hot water to distribute heat over the floor surface. However, underfloor heating also requires underfloor insulation.  Otherwise, the energy used in heating the floor ends up heating the void unnecessarily, resulting in poor performance and higher energy costs.

 

Use a robot to spray underfloor insulation

Q-Bot’s solution involves a robotic device that spray-applies insulation without you having to leave your home, and is one of the cheapest measures to increase your Energy Performance Certificate (EPC) rating for your property. The installation process takes only one to two days for an average UK property and is immediately effective, reducing draughts, improving thermal comfort, and even reducing sound when you walk across your floor. The insulation process is simple. First, the robot enters the void through an air vent or a small access hatch in the floorboards. The robot travels through the void, scanning and creating a 3D image of the underfloor to ensure the property is suitable. Next, the robot sprays insulation foam to the underside of the floorboards. The insulation expands and fits the shape of the floor, ensuring no gaps are left. It does not fill the entire void, allowing for a ventilation gap between the insulation and the ground beneath to protect from damp and mould. Finally, the installation is scanned and checked to verify that the work has been completed successfully. 

 

 

Latest environmental concerns, government legislation including the target to bring all UK greenhouse gas emissions to net-zero by 2050, together with homeowners' expectations of thermal comfort and energy savings are all significant drivers to insulate your floor. 

Speak to your local energy provider to find out more about what sort of funding is available to you for your insulation needs.

If you are renting a property, following recent legislation, your landlord also has obligations to take energy efficiency measures that can help you save energy and feel more comfortable.

If you don’t already have some form of insulation installed, and want to review all the insulation options for your home, have a read of our Best Ways to Insulate Your Home article.



 

Learn more about floor insulation and energy efficiency:

Floor insulation, by the Energy saving trust.

Funding for energy efficiency, by Simple energy advice. 

Energy Performance Certificates (EPC), by the Energy Saving Trust

What is thermal bridging? by the Greenage