Vysa-Mat Classic can be used on timber sub-floors but BSEN 60335 recommends that the power rating must not exceed 150W/sq m and you must install Vysa-Pron thermal insulation on top of the timber sub-floor.
The timber sub-floor must be suitably prepared to prevent movement that could cause the tiles to lift and the grouting to fail.
First check that the floorboards or the chipboard sub-floor is securely fixed to the joists. If in any doubt use countersunk head screws or ring nails at 300 mm centres across the whole area to fix the sub-floor securely to the joists.
We recommend that 18mm thick plywood is fitted over the original floor to prevent movement. The plywood must be fixed over the original sub-floor using countersunk head screws at 300 mm centres across the whole area.
Don’t forget to cut a channel into the floor for the 10 mm diameter flexible conduit for the floor sensor. The channel should be deep enough for the tube to finish sub-flush to the surface.
Insert the floor sensor into the 10 mm diameter flexible conduit and check that the red plug used to seal the conduit is in place to prevent ingress of adhesive or cement.
Install the flexible conduit into the channel cut in the floor and secure the remainder to the wall and wall mounting box for the thermostat.
Fill the channel in the floor with a suitable filler or leveller compound to make the floor smooth and level again.