Underfloor Heating Installation: How-to Lay Wet UFH Yourself

Underfloor heating installation is not an easy task but for a competent DIYer it is one that could save you money on your project – if you have the right skills. 

While a lot of the underfloor heating installation can be carried out yourself, there are some aspects that are notifiable. These elements will therefore need to be completed by a qualified professional. The key ones being installing a new underfloor heating manifold for a wet system or connecting up a power source for electric underfloor heating.

Whether you are planning to lay your underfloor heating as a DIY project, or you simply want to understand the process, our sustainable building expert Tim Pullen explains how in this step-by-step guide for wet underfloor heating. 

Of course, it's important to remember that you should only take on DIY projects that are within your capabilities. If you make a mistake, it can cost you more to rectify than the initial cost saving in the first place.

How do I install wet underfloor heating?

Before starting, it's worth having a plan about where your pipes are going to sit as well as having all the equipment and tool you need ready to use.

1. Connect the pipe to the manifold 

The first step is to connect the floor heating pipe to the underfloor heating manifolds. The manifold will have already been installed by a professional and you shouldn't undertake this on a DIY basis. 

2. Lay underfloor heating insulation

After laying your insulation, you will need to begin to lay the pipe. This is an important element, and shouldn't be overlooked — laying insulation under underfloor heating will improve the efficiency by resisting the heat from going downwards 

3. Begin to lay the pipe

After laying your insulation, you will need to begin to lay the pipe. Make sure to clear the subfloor before laying out the pipes to ensure there's nothing that will damaged the pipes. 

4. Fix the underfloor heating pipes 

Secure the pipe to the insulation as you go using pipe staples. Ensure you fix the pipe with the correct spacing to ensure optimal heat distribution.

5. Install across the whole floor 

Loop the pipe across the whole floor area, using multiple loops for large spaces.

6. Prepare the screed 

Mix the screed or opt for a ready-mixed version. The pipes must always be pressure tested before the floor screed is laid. Equally important is to ensure the pipes are full of water while the screed is being laid so that if there is any damage it will be immediately obvious and can fixed before the screed laying is finished.

7. Pour the screed

Carefully pour the self-levelling screed over the pipework, ensuring that the pipes are securely fastened and the insulation is sitting flat. 

The screed is stabilise with a chemical spray, before being finally tamped for a smooth finish. 

8. Leave to dry

Leave the screed for at least 7 days to dry before turning on the underfloor heating. At this point, turn the underfloor heating at the lowest temperature, gradually increasing it over a number of days.