Installing a stone floor is a lot like installing ceramic tiles. Much of the installation is similar. However, there are differences you need to know, and which will influence your decision to do it yourself or to hire a professional.
Stone, unlike ceramic, is not uniform in thickness or width. Its cut from rock, not molded, which is part of the appeal. If installed properly, you can compensate for varying thickness by varying your mortar thickness, but its not an easy task.
Stone doesnt cut the same as ceramic. You will need to buy or rent a stone cutting saw with a diamond-edged blade. A quality saw can cost upwards of $500. A cheap saw can cause severe aggravation, so its not really an option.
Stone is very heavy and rigid. It requires a very solid underlayment that wont shift at all. Flex in the subfloor will cause cracks in the stone.
That said, lets go over whats involved in laying your own stone.
Prep Your Floor
Be certain that your subfloor is level and flat. Sand high areas and fill low areas with leveling compound.
If your existing subfloor is not at least 3/4 thick, an additional layer of 3/4 plywood is necessary. The floor needs to be well-supported underneath. If it flexes under the weight of people and furniture, the stone is going to add to this stress. Reinforcing the framing may be required. Some floors may not support stone at all due to the weight.
In the case of cement subfloors, mortar and tile can be applied directly.
Wood subfloors require a concrete backer board. This is glued and screwed to the subfloor.
Prep The Trim
Cut door jambs to accept stone using a jamb saw or pull saw. Remove baseboard before installation, and the reinstall it when you're finished.
Set Your Stone
Pull your stone as you work it from different boxes. Stone varies in color, but this allows for variance to be spread out and to blend.
Be flexible. Level the floor as much as possible by varying your thinset mortar amount to compensate for tile variance.
Seal & Grout
Seal your stone before grout keeps the grout out of the stones small fissures and pits. This makes grout cleanup easier.
With natural stone, unsanded grout is best because it fills small joints better and will not scratch soft stone.