This is abit complicated as different areas in the world have different building techniques and I am not sure that any of you can help but here goes anyway.
The house is a new build in in Israel's Negev desert. The building is concrete and high tech brick. The floors are all tiles of different types that are laid on a layer of sand and mortar.
Most of the work has been carried out by a big contractor and has been a real nightmare but that is another tale altogether. Now I am at the final stage, more or less, and the contractor refuses to lay the slate floors on the second floor verandahs (which overlie some of the first floor rooms) claiming that slate is not suitable nor does he know how to use it.
The concrete and brick roof (also the floor of the verandah and second floor rooms) beneath the planed floors has been sealed. On top of the sealer there is a layer of dry sand about 15 cms (6.5 inches) deep that has in it plumbing, electrics etc. On top of the sand we need to lay the slate which will be held in place by a layer of mortar which rides between the sand and the slate. This is the standard procedure in this country where we use very little wood and especialy in this area which is full of termites.
1. Is slate a suitable material, once sealed of course, for use in this way ?
2. Is there any type of mortar more or less suitable under slate and what ratio of sand to cement should I use ?
3. In mixing the mortar should I use a liquid other than water ?
4. What slope, 1% or other, should I use to gaurantee fair drainage.
5. Am I completly mad to attempt this project by myself ?
Wow what a project. I would say it is completely doable. You never said what size of slate you are working with but here in the states we will install what we call paver patios which is a brick or stone peices that are laid over a compacted bed of sand. The brick or stone pavers are just butted together tightly and after installed, sand is brushed over the surface to fill in any left over voids and lock it all together. I'm not sure about the mortar idea but I think it would work.