How to lay underfloor heating

Underfloor heating is becoming progressively more popular in the UK. Steady growth over the last few years has contributed to its increasing prominence in the heating market. As a cost-effective and economical solution to indoor heating needs, underfloor heating is being installed in more domestic properties than ever, both in new builds and as a retrofitted system. If you’re looking to install a system either for yourself or on behalf of a customer, then it’s important to know how to lay underfloor heating.

The different types of underfloor heating

How underfloor heating should be laid in a roomWhen looking at installing underfloor heating, you will generally be presented with two options: wet (hydronic) and dry (electric). Both can be used with different types of flooring, but each comes with different advantages and disadvantages. Wet systems provide heat by pumping warm water through pipes underneath your floor, while dry systems do so with the use of mats featuring electric coils. Don’t choose a wet system if you are not able to raise your flooring to accommodate it.

The main advantage of using a wet underfloor heating system is the cost of running compared to radiators, due to the lower temperature needed to work effectively. However, they are more difficult to install and therefore may come with higher initial costs. An electric underfloor heating system is great for a smaller area, as it will be easier to install but generally more expensive to run. It also rarely requires raising the flooring, so is often a better option for retrofitting existing properties.

If you are unsure as to what system will work best for you, please contact our sales team.

How to lay underfloor heating

1. Pull up the flooring and clean the subfloor

If you’re retrofitting, the first thing to do is pull up the floors and ensure that the subfloor is clear. If flooring is installed with a tongue-and-groove system, pry the nails out from the floorboards in order to remove them. Start with the boards closest to the wall. Use the subfloor to lever your crowbar for the rest of the boards in order to save them from damage. If you have a click system, you should be able to simply pry up an end board before removing the entire floor in one piece. You can then unclick the individual boards from below.

Next, ensure that the subfloor is clear of any debris which might pose a risk to your heating system. Simply file or cut away any sharp edges in the area so that there is no risk of damage to the pipes once they are installed. In many properties, a damp proof membrane will need to be added on top of the subfloor.

2. Lay the insulation and install the manifold

First, lay your underfloor heating insulation and ensure that it does not contain any large gaps. Place the insulation as neatly as possible and tape the joints to prevent screed from making its way underneath. If you are installing a wet system, the pipe fixing system should then be fitted on top of the insulation at a 90-degree angle relative to the direction in which the pipes will be laid.

Next in a wet system is to install the manifold, to which your pipes will be connected. The manifold should be mounted on a wall that will be strong enough to support its weight when connected to the water pipes. Place it in a central location, and around 1 metre from the ground.

3. Lay the water pipes or electric heating mats

An example of dry (electric) underfloor heatingIn a wet system, you should lay the water pipes once you have mounted the manifold. Follow the instructions and guidelines provided by the manufacturer of your heating system. Plus, make sure that the pipes are spread evenly across the entire area that you wish to heat. Leave around 200mm spacing between each section of piping, which should run from the manifold to the furthest point in the room. A qualified plumber should complete the connection of the system to the water mains.

For dry systems, you should find it fairly simple to lay the heating mats. Again, follow the manufacturer’s instructions for securing them in place, and ensure that they are spread evenly across the area of the room. You will also need to install a floor sensor to provide a temperature reading to your thermostat; this should ideally be placed close to the wall on which the thermostat is installed. A qualified electrician should complete the connection of the system to the electrical mains.

4. Cover the heating system in a layer of screed

Both wet and dry underfloor heating systems tend to include a layer of screed. This helps to keep the heat insulated, as well as improving the system’s performance. First, make sure that the insulation is flat and the pipes or mats are securely fastened. Next, lay sand and cement screed around 75mm thick on top of the pipes or mats. Allow the screed to dry naturally before the heating system is turned on, otherwise it may be damaged. This process should take no more than seven days.

5. Warm the system up slowly

Test your underfloor heating system before use by turning it on at low temperatures. As long as everything is connected correctly, and you allowed the screed to dry, there should be no problems. However, turning the system up to full heat straight away can cause damage, so it should be increased slowly the first time.

For more information, contact our insulation experts on 01752 692 206 or use the live chat facility.