I have had (lightly) polished limestone tiles (15 mm) laid at 4mm intervals on a 2 inch mortar (sharp sand & cement) bed on 4 inch compacted hardcore sub base. Its all gone down well and is nice and solid. My priority now is to make the right choices to ensure it lasts well:
My main concern is frost damage, the limestone seems to be more porous than I had expected and i want to reduce any chance over the winter of water being absorbed into the stone then freezing and rupturing the tiles.
As I see it I have two choices: I either use a permeable sand/cement based grout to help drain water off and into the ground or I seal the limestone and use a waterproof grout to prevent water (from above) ever entering the stone in the first place.
Apart from the obvious disadvantage that a waterproof system will drain poorly as it relies purely on gradient drainage and evaporation to clear surface rain. Are there any other considerations or words of warning people can offer?
I am planning to do a worst case scenario "wet freezer test" on a spare piece of tile to try to gauge how concerned I should be about frost damage.
You'll stain the he'll out of them doing a cement grout in 4mm joints on pourus limestone, I'd use a polymeric jointing compound such as gtfk or romex or new marshals one. Bit tight at 4mm but be a lot easier than sand cement.
Where a bouts are you? As big difference from up north to down south in the severity of the frost?
Giles
Groundworks and Equestrian specialists, prestige new builds and sports pitches. High Peak, Cheshire, South Yorkshire area.
