Suspended ground floor; tile flooring

Purpose of a suspended ground floor

A suspended ground floor is raised above the ground with a ventilated void beneath. It is provided to stop dampness rising into the floor, to ventilate the timber and prevent dry rot, and to give a warm floor surface. It is used on damp sites, sites with a high water table, and sloping ground.

Construction of tile flooring

1. Base preparation: the RCC slab or concrete sub-floor is cleaned of dust and mortar and wetted. A level line is marked on the walls.
2. Mortar bed: a 20-25 mm bed of cement-sand mortar (1:4) is spread, stiff and level, to the required slope.
3. Slurry coat: a thin layer of neat cement slurry (or adhesive) is spread over the bed.
4. Laying tiles: the tiles are soaked (for ceramic), then laid from the centre or a corner. Each is pressed and tapped with a rubber mallet, checking line and level with a straight edge and spirit level. Spacers keep the joints at 2-3 mm.
5. Grouting: after 24-48 hours the joints are cleaned and filled with cement or coloured grout. The excess is wiped off with a damp cloth.
6. Curing and cleaning: the floor is cured for 3-7 days, then cleaned with a mild acid wash and polished.

   tile 8-10 mm       =========
   slurry             ~~~~~~~~~
   mortar 1:4 (25)    .........
   RCC slab / PCC     ---------