Once the floor has been secured using the methods described in preparing timber backgrounds, it should be checked to see if it is out of level.
The following method may be used to achieve a level floor. Any gaps between timber sheets or floorboards should be filled and badly worn or damaged floorboards replaced. Arditex levelling compound can be applied from a feather edge up to 12mm thick as required.
Once the Arditex has thoroughly cured an overlay of 10mm tilebacker board may be laid across the surface and screw fixed through the Arditex and into the timber floor. It is important to use the PW60 washers when using screws with Wedi as they stop the screw heads tearing through the board and provide a secure fixing. The screw fixings must not be further apart than 300mm, with care being taken to ensure the corners and edges are securely braced. Arditex levelling Compound should never be used on timber unless covered with an overlay.
The levelling method is slightly different when using Ditra matting. Once the timber floor has been secured, attach the Ditra matting using Ardex AF200 adhesive. The Ardex AF200 adhesive will cover approximately 3 square metres per litre using a 2x6mm vinyl notch trowel. Seal any joins in the Ditra by fixing Kerdi Keba jointing tape with flexible adhesive. Arditex levelling Compound may be applied on top of the Ditra matting to provide a level floor surface. Unlike the previous method there is no need to overlay the Arditex with boards before tiling.
Ditra Matting requires filling to make a smooth surface for tiling. As a guide the following amounts of adhesive or levelling compound should be allowed for when working out the required quantities.
Adhesives: approx. 2 kilos per square metre
Levelling compound: approx. 2.6 kilos per square metre
If a securely fastened timber floor is too uneven for Ditra matting to directly follow the contours then it may be necessary to apply Arditex levelling compound first. Ditra matting can be used to overlay levelling compound in the same manner as Wedi board but without the need to use screw fixings. The Ditra matting can be fixed to the Arditex with Ardex AF200, once the levelling compound has cured and hardened. Kerdi-Keba band should be used to dress the joins in the matting and a smoothing layer of adhesive is required before tile fixing takes place.