concrete on concrete bathroom floor

[burn1]

My new ensuite is being built over an existing little concrete balcony.Bth/shr is installed already in a hebel wall. I need to raise the floor of rest of room about 100mm and have a fall to a drain in the middle. Should I use concrete (25 bags I caculate) and if so what type and how do I make it stick on old concrete or should I use Fibrous boards.(But then how do u get the fall in the boards.

[juan]

Have you had an engineer's report that the balcony can support another 100mm of concrete loaded on it?

Assuming it is able to, then I would be looking at putting another layer of concrete with light reinforcing on top of the existing floor with the fall built in to the drain to save screeding later. Provided the existing concrete is clean and a bit roughened it will adhere but 100mm thick is not going anywhere so even if it it did not adhere it would not cause an issue methinks.

Cheers

[patty]

I use Fibrous boards.(But then how do u get the fall in the boards

As Juan has stated get engineers report done on balcony first!!!

You dont have to have fall on the concrete bed into the waste as the tiler will lay another cement bed down over the one you pour and screed to the waste locations then tile over the same will be with CFC sheeting!!

Pending on Accessibility a picture of the job would be much easier to make comments on the mixing issue you have mentioned a balcony is this 2 storey house or unit??
Do you have to have the Concrete so thick in all areas or can you bulk it up in the center with sand then black plastic and drop the sides???

[burn1]

the concrete slab from the old balcony is 2.2m x 1.7m with brick walls supporting the 2.2m length and only 0.5m off the ground. Bth/Shr is on this slab aswell though it is also cut into the framework but resting on a mortar bed.