How to fit insulation boards

Underfloor heating insulation boards are boards that are placed underneath your flooring to help speed up the process of your underfloor heating, whilst also ensuring that the optimum heat levels are retained. They are manufactured from water-resistant extruded polystyrene, finished on both faces with a thin layer of fibreglass reinforced cement. 

The insulation boards are available in a range of thicknesses, from 6mm to 50mm suiting any individual project requirement. The 0.5mm thick cement coating provides an excellent surface for tile adhesive, plaster and levelling compounds, with no priming required.

Insulation boards are ideal for use with electric underfloor heating as they prevent the heat from the heating system escaping downwards to the subfloor, saving you both energy and money.

The low thermal conductivity of the insulation board enhances the efficiency of underfloor heating systems, even when used over pre-insulated subfloors. This is because the insulation board prevents the thermal mass from escaping downwards, significantly reducing the amount of heat absorbed by the subfloor. This allows the underfloor heating system to warm the floor and the room up faster.

By reducing the amount of time the room takes to warm up and cool down, the room can spend longer at its cooler set-back temperature – reducing heat loss and conserving energy.

With the insulation boards, the floor on a concrete base will heat up within 30 minutes to an hour. Without the insulation boards, the heat up time will be significantly longer, anywhere between two to eight hours. Read the rest of the guide to understand how to fit insulation boards for underfloor heating.

Due to their waterproof properties, Warmup or Wedi insulation boards are perfect for insulating bathroom and wet room walls. They can also be utilised as tile-backing boards, making them perfect for installing with the Promat Heating System which brings a luxurious sense of 360 ͦ  warmth to cold tiled bathrooms.

As long as the joints of the boards have been sealed, wall tiles can be applied directly onto the insulation boards or over the heating system.

Determine how you will be laying out your insulation boards in advance, based on your room layout and then cut the boards to size with a retractable knife.

Whichever substrate you are installing the boards onto, it’s important to remove all traces of adhesives, glues, contamination, etc. before fixing and if you’re using them in a wet area, such as wet room, you will need to seal the joints and screw holes using the required sealant as per the manufacturer’s guidelines.

When installing over a new concrete base, make sure that it has been properly cured before installation. Prime the concrete substrate using BAL Primer.

The board should be fixed to the concrete base using a flexible tile adhesive using a 4mm trowel, stagger all the joints in a brick like fashion and ensure that there are no voids and the boards, taping the joints with Warmup glass fibre tape.

For waterproof applications you will need to seal the joints using the required sealant, as per the manufacturer’s guidelines.

Existing floor boards must be structurally sound and if necessary, smoothed with a latex self-levelling compound. Secure the boards to the base using screws and washers, 12 screws per board (3 rows of 4). The screw washer should be tightened into the board flush with the surface of the board. Stagger all the joints in a brick like fashion and tape the joints using the Warmup glass fibre tape.