How to fit electric underfloor heating in a garden room

This garden room was put up during the 2020 lockdown for a quiet place to work and a breakout space for anyone who needed some time on their own. The only heating was a plug-in radiator and a fan heater, which turned out to be expensive to run and also took a while to heat the cabin up.

There were cables everywhere and since the lockdown was lifted, the use of the room had changed a little – it was now a workspace for 2-3 days a week and the rest of the time it was a teenager zone for gaming, sleepovers and personal space.

We used Cableflor to retro-fit underfloor heating, re-position the broadband hub to the ‘gaming zone’ and get rid of all the loose cables. Our electric underfloor heating kit comes with a smart thermostat, so you can adjust the heating from your phone, ensuring the right temperature for when you need it.

First we lifted the existing floor coverings, which were going to be reused. The area under the fridge, cupboard and drawers weren’t going to be heated and neither was underneath the corner sofa – these areas were quickly marked out with masking tape and the Cableflor brought in.

It was easiest to start underneath the sofa and then work our way across the room – wherever you decide to start, point the ‘slotted’ sides of the Cableflor sheet into the room. The other sides have tabs, so it’s very easy to spot.

Lay the sheets next to each other to complete your first row, ensuring that the arrows on the Cableflor are all pointing the same way. Where you need to trim the last sheet, just tear off the required rows – start pulling it apart from a side with tabs, then it will come off in one strip.

To clip the sheets of Cableflor together, it’s easiest to push the tabs down into the slot, hence the orientation tip! Push either end in first, then lift the centre to make sure it lines up, push the rest of the tabs in.

Centre your first row over the width of the room – it’s unlikely to fit exactly and rooms aren’t always square. We supply firm foam strips, the same height as the floor, which you can quickly cut with a pair of scissors, to fill any gaps or difficult angles.

The purpose of the foam is to support any floor covering so that it doesn’t droop over time – these gaps are always too small and close to the wall to be stepped on or have furniture on, so they don’t need to be structural.

Our electrician fitted the thermostat and connected the heating cable and temperature sensor beforehand, so that it could all be tested before laying.

The thermostat needs to be about 1.5m up from the floor and near a power source. Decided beforehand where you will need the heating to be laid, so that you can allocate a start and a finish position.

If you would like us to do you a quick CAD drawing of your space, just email with a dimensioned sketch the shows furniture and power positions.

It’s also useful for working out what length cable you will need and it’s so much easier to work from a drawing when installing.

The heating cable is going to be pinned down using our supplied cable clips, into rows that are 10cms apart, which will fit inside the channels in the Cableflor. You can either mark out the rows with a tape measure, but we prefer to tear off rows of Cableflor and use them to mark out the floor instead – it’s quicker and ensures the mark is in the centre of the channel.

There are two cables supplied with your kit – the long blue one with the black end is the heating cable. The black end (called a cold tail) goes into the thermostat and the blue section get hot. The other cable is black and much shorter – this is the temperature sensor, which also goes back to the thermostat. Pin this down in the first marked channel or 50mm away the edge of the Cableflor.

Then pin down the heating cable – you only need to fit one clip per corner, just pull the cable gently at either end to keep the cable straight. The best thing about using a loose heating cable is that it is really easy to go around obstacles and only heat the part of the room that you need.

Cover the heating cable with the Cableflor as you go along – this will guarantee that your cable is in the right place and it also gives you something to walk on. The cable manufacturer says that it’s absolutely fine to walk on, but let’s not take any chances!

Work your way across the room and then lay the floor coverings back on top of the Cableflor. The whole installation only took 4 hours and didn’t require any cement or levelling compound. The heating cable remains accessible in case the room changes layout again – the Cableflor gives a nice flat surface for your floor covering, without putting any pressure or weight on the heating cable.

Take a look at our quick and easy to install underfloor heating kit here.

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