How to Install Underfloor Heating in Your Bathroom

Getting out of the bath or shower is always something we try to put off a little. That cold chill from the air or that icy touch from the floor as we step onto it is never something we welcome. That’s perhaps why more and more of us are considering the option of underfloor heating in our bathrooms. 

It may seem a drastic jump to go to installing a whole heating system, but underfloor heating systems don’t just warm up your feet once you leave the bath or shower. They help save space compared to other heating options, improve air quality by reducing dust circulation and are more energy efficient than other heating methods. Those aren’t the only benefits though and to go into them all would be a whole new article altogether.

So, if the small number of benefits we have covered already has got you wondering if it could be a good investment, let’s look at how you can install an underfloor heating system in your bathroom.

Can you install underfloor heating yourself?

So can you install underfloor heating yourself? The simple answer is yes however with any DIY project there should always be the caveat that professional guidance is always advised. It would be a shame for you to spend cash on trying to do it yourself only to find you’ve made several mistakes along the way and now your bathroom flooring is compromised. 

If you do choose to do it yourself, be prepared for it to take a little time, it’s certainly not a five-minute job or one you may finish in an afternoon. Much depends on your level of competency with DIY projects. You should definitely set aside a good few hours. In many cases, you won’t just be laying the underfloor heating system but also the bathroom flooring on top of it too.

Different floor types take varying amounts of time to lay so it would also be worth factoring that into your task list. Furthermore, some floor types are a little more complicated than others so it may be that you can set the heating system yourself but require the help of a flooring expert for the floor surface.

The steps to follow to install underfloor heating in your bathroom

Before you do anything, you should ensure you have all the correct tools and accessories to make sure you can get the job done. This would include:

  • A multi-meter
  • Scissors
  • Duct tape
  • Tape measure
  • Waterproof tape
  • Hammer
  • Chisel
  • Insulation boards
  • Underfloor heating thermostat

And of course, the underfloor heating system itself. Now, some of the items above may not be needed and it may vary depending on what type of flooring you lay over the top. It’s best to be prepared though so grab them all then at least you’ll be well-equipped!

Measure the space

Perhaps we jumped a little ahead by saying to have your underfloor heating ready in advance of the task. You do, but before you even order any, you’ll need to know how much you need. The fixtures and fittings of your bathroom won’t require any underfloor heating and you’ll also need to make sure there is a gap of around six inches between any walls and permanent fixtures. Take this into account when measuring the space that you require the underfloor heating to fill.

This will save you money as you’ll only order what you need, but to be safe, order just a small amount over the final measurement in case there are any awkward spaces you may need to fill.

Order your underfloor heating

Underfloor heating systems come in two types. Mat or cable. The shape of the bathroom will determine which type you need. If your bathroom is a regular shape a mat option would work best, if its shape is a little more irregular, the cable option would deliver the best results. Then order the thermostat and the insulation boards. The boards are optional but will help keep heat in and save you money in the long term.

Read the instructions

This may sound like common sense but how many times have any of us attempted a board game, a flat-pack furniture item or a recipe, assuming we know best, and that the instructions will get in the way? Now you’ve given it some thought, you know you do it too! So, read the instructions for your underfloor heating, it will save you lots of time later on.

Clean and prep the area

Before laying any underfloor heating, you’ll need to make sure the surface it’s being laid on is clean and free from obstructions. Sweep, hover, wipe. Do whatever it takes to make the surface the underfloor heating can attach to free from anything that may hinder the task.

Take a resistance reading

With your underfloor heating unpacked, use your multimeter to take a resistance reading from the end wires of the underfloor heating. This reading should be compared against what is shown in the user manual. The result, hopefully, will match what is shown in your manual. Note these numbers down though as you will need to test the resistance again nearer the end of the task.

Lay the insulation boards

These boards aren’t a necessity but will certainly be worth the investment. They prevent heat from escaping and ensure you get optimal use from your bathroom underfloor heating. Simply lay the boards over the surface area of the bathroom floor. You’ll need to cut some to size to fit the awkward spaces. Use the utility knife for this. Then, with the waterproof tape join the boards together. For added strength, if there are wooden floorboards underneath, you can screw the insulation boards down if you wish.

Lay the underfloor heating

With all the prep done, you can finally lay the underfloor heating. If it’s the mat style, simply unroll it. Just remember you’ll have two wires that need to be connected to the thermostat so positioning them as close as possible to it will be essential. You can then attach the flooring to the boards using the duct tape. Make sure no edges are sticking up. If they aren’t you should be good to go! Just remember to leave a suitable gap of 6 inches between the walls of your bathroom and the underfloor heating.

Take a resistance reading

Now with the underfloor heating system laid out, check the readings again. This will ensure that during installation there weren’t any parts of the wiring or mesh that got damaged. If the readings are not right, seek guidance from the underfloor heating manufacturer.

Install the temperature sensor

This sensor will monitor the temperature of the underfloor heating so installing it correctly is important. If it isn’t the thermostat won’t operate as it should, and you could have a floor that’s too cold or far too hot! The sensor must be placed between any two lines of wires close to the edge of the room where the thermostat is. Use your duct tape to attach the sensor to the flooring system.

Take one more resistance reading to see if the system is still as it should be.

Connect the thermostat to the flooring

This should be fairly simple, yet each set-up could be slightly different so carefully check the manual to ensure a correct connection is made. Once the flooring is connected to the thermostat, the thermostat must be connected to the mains power supply. This particular step can only be completed by a certified Part P electrician.

Once this is done, take one final resistance reading.

Lay the bathroom flooring

Now you can lay your chosen bathroom floor. What type you use should be considered before installing an underfloor heating system. Some types don’t allow heat to pass through very well, and others may be damaged by the heat coming from the system. Tiles are often a popular choice and as grout can be added over the top of the mesh sheets, you get some additional insulation for the wiring at the same time. 

One choice of flooring that lends itself well to underfloor heating is LVT or Luxury Vinyl Tiles. Bathroom flooring made of LVT comes in a variety of styles that replicate stone or wood but have the bonus of being easy to clean, hygienic and a great conductor of heat. They can be installed by you, but for the best possible outcome, it might be better to ask an installer from a company like Amtico to do it for you. 

You’ll notice you now have some tools that you didn’t use perhaps but in some cases, you may well do! You should also now have a perfectly laid underfloor heating system with a nice bathroom flooring design on top!