How to install underfloor heating

Underfloor heating can be used to warm the floors in your property as a primary heat source, replacing your heaters and radiators. There are 2 main forms of underfloor heating, electric and water systems.

Electric unfloor heating

Electric floor heating rely on a network of wires or coils under the flooring that heat up. These are linked up to the thermostat and the mains electricity which allow the floor to be heated. Whilst these are cheap to install, it will cost more to run compared to a water underfloor system, meaning this type of system would be more suited to small rooms and areas of your property.

Water unfloor heating

Wet heating systems work through water being pumped through the pipes that are laid under the top surface of the flooring. This reduces the cost of water heating, compared to radiators and heating as these require water to be heated at a much lower temperature to work efficiently.

Water systems tend to be more suited to new build properties or extensions, as these can be easily installed by pulling up the floor and putting them back into place following installation. Due to this, water underfloor systems are more suitable for ground floor rooms. 

How to install unfloor heating

Underfloor heating is not a hard task to undertake, however it is recommended to have some basic DIY skills, as well as plenty of free time before undertaking the project. You should be able to do the majority of initial work yourself, but you will need an electrician and/or plumber depending on the type of underfloor heating you decide to go for, as they will need to connect the system to the main electricity.

Whichever type of underfloor heating system you decide to go for, you should make sure that the rooms that you have chosen to install these are properly insulated, so that the heat is not immediately negated. You should also ensure that the subfloor does not have any debris around it, as well as making sure the joins between the insulation material are taped correctly to prevent any losses of heat from them.

You should also make sure insulation materials are included below the system you are installing, so no heat can escape through the subfloor and foundations. If you are installing an electrical system, you will need an electrician present to connect the system to the main.

Wet heating systems tend to be more difficult to install, as well as having higher initial costs, whilst electrical heating systems are great for small areas or rooms. These will also be easier to install but can be more expensive to run compare to water underfloor systems.

1. Pull up the flooring and clean the subfloor

The first thing you should do in the process of installing underfloor heating is to pull up the floors, and ensure all subfloors are clean and clear. It is recommended to start with the floorboards closest to the wall.

The way you pull up the floor will all depend on the placement it currently utilities, and most will have the tongue and groove system, or a clicking system. If your flooring is installed with a tongue and groove system, you should pry the nails out from the floorboards to remove them, and it is also recommended to use the subfloor to lever your crowbar for the rest of the boards. This will save them from damage, and ensure you are able to use these again.

If you have a click system, you should be able to just pry up one of the ends of the floorboards, before being able to remove the entire floor in one piece.

2. Laying the installation

When laying down the underfloor heating insulation, you should ensure it does not contain any large gaps. It is recommended to place the insulation as neatly as possible and you should also tape the joints together.

If you are installing a wet system, the pipe fixing system should be fitted on top of the insulation at a 90 degrees angle, relative to the direction in which the pipes will be laid. The manifold would then be the next item to install, and this should be mounted on a wall that will be strong enough to support its weight once connected to the water pipes. This should be placed in a central location, and around 1 metre from the ground.

The water pipes can then be laid once the manifold has been mounted. You should also ensure the pipes are spread evenly across the entire area that you wish to heat. Around 200mm spacing should be left in between each section of piping, which should run from the manifold to the furthest point in the room. Once installed, a qualified plumber should then be able to complete the connection of the system to the main supply of water.

For electric underfloor systems, it should be fairly simple to lay the heating mats, and you should ensure they are spread evenly across the area of the room. You will also have to install a floor sensor, which will provide a temperature reading to your thermostat. Ideally, this should be placed close to a wall where the thermostat is installed. Once this system has been fitted in, a qualified electrician should be able to complete the connection from the system to the electrical mains.

Covering the heating system in screed

Electrical and water system will both include a layer of screed, which will help the keep the heat insulated as well as improving the system’s long-term performance. It is key to ensure the insulation is flat and the pipes or mats are securely fasted. 75mm of sand and cement screen should then be laid on top of the pipes or mats. You should ensure this is dried naturally before the heating system is turned on, otherwise this may cause future damage.

It is key you also test your underfloor systems before using at full power. You can do this by turning them on slowly at low temperatures. As long as the systems are connected correctly, and you have allowed the screed to dry naturally, there should be no issues. However, it is key to warm up the systems slowly before using at high heats, as this can cause damage.  

Pros and Cons of Unfloor heating

Underfloor heating pros

Comfort – It’s the middle of winter and the thought of getting out of bed is terrifying, but at least you can walk barefoot to the toilet without screaming. And stepping out of the shower onto warm ground is just lovely.

Safety – With underfloor heating you won’t have sleepless nights about your kids or young family members bashing into sharp edges or burning their hands on hot radiators.

Easy to run – Requires very little to no maintenance and often comes with a lifetime guarantee. No more pretending to know how to bleed the radiator…

Better heat efficiency – Heat is now evenly distributed around every room and works at a lower temperature than a traditional radiator, so your energy bills could actually come down. And your floors will stay warm even if the windows are open or a room is very draughty.

Increased home value – Because underfloor heating is a desirable feature for home buyers, your property will be worth more when it comes to selling. It’s not a lost investment if you end up moving sooner than planned.

More space and design freedom – With no radiators and a hidden heating system, you’ll have more space on the walls.

Installation – It’s possible to install it yourself and because underfloor heating systems work well with tiles and stone, it’s an ideal choice for kitchens and bathrooms, i.e. where it will be needed the most.

Underfloor heating cons

Cost – The initial cost can be considerable and the installation of the system can cause a lot of upheaval in your home. In older buildings, creating the right conditions under the floor may also be pricey.

Time – Underfloor heating takes longer to fire up than a radiator, so you have to use a timer to predict when you want heat in certain rooms.

Furniture – You can’t use it under some items of furniture or fittings, which restrict how you set up your home. Large, heavy items may have to go altogether.

Installation – If you go for a water-based system, you’ll need to pay a professional to install it. Meanwhile, smaller systems may not heat enough of the room and require radiators anyway.