Prpearing a floor with Hardie Backerboard and then self levelling compound

[merlecollins]

Just thought I would provide a thread giving start to finish guidance for installing Hardie Backerboard. On this job I also needed to end up with a perfectly level floor as the customer and I decided on showing a full wall tile up from the floor. The wayrock flooring has wet underfloor heating pipes underneath.

This is the first photo taken before I started - apologies for the image quality but I only had my Blackberry with me

1. The first job was to clear all the room out and give the floor a good sweeping with a soft brush

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2. Next photo a bit closer before I started....the two chrome pipes at the back of the room are freestanding taps for the bath.

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3. After cutting and dry laying all the HBB boards, I removed them and stacked them in order in another room. I had marked the line of the first two boards and then began serating the single part flexible adhesive (Mapei Keraflex if I remember correctly) - I mix the adhesive for HBB boards slightly wetter than I would normally do for tiling.

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4. I then carefully laid the previously cut boards into the adhesive along the line I had marked onto the wayrock flooring, the boads are then screw fixed approximately every 150-200mm through the adhesive into the wayrock flooring - ALWAYS be super careful of the length of your screws as the LAST thing you want at this stage is water spraying everywhere from a punctured pipe beneath the wayrock......

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5. I leave a nominal joint width of approximately 5mm between the boards which is then taped with self adhesive fibre joint mesh...

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6. These taped joints are then filled with the same single part flexible adhesive that the boards were bedded into - I use a flat faced sponge just to smooth this filling adhesive after filling, just to ensure a flat surface for tiling...

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7. This next photo shows the floor preparation at an advanced stage, although still not complete....

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[merlecollins]

8. Unfortunately the original wayrock flooring was 8mm out of level and as I had agreed with the customer to show a full wall tile up from the floor tiling I needed to make the base perfectly level.

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9. I did this by fixing a strip of HBB ( with adhesive and screws as the main floor) approximately 120mm wide along the lowest point of the floor - this would act as a screed runner for me to rest a straight edge on...

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10. Once the screed runner and the rest of the boards have had time to set properly ( I left this floor overnight as I had used a slow set ahdesive) I laid a fibre reinforced self levelling compound, working off the runner, to a width of 1800mm across the room and was left with a perfectly flat and level base for tiling....:hurray:

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