Ground Floors – Ground Bearing – Below concrete/slab
 
The Rockfloor boards are laid lengthways to the longest wall, in a staggered joint pattern, tissue face upwards. The off cut at one end of the first row is then used to start the next row and similarly with subsequent rows.
 
Under slab applications

Rockfloor may be placed under the slab, provided the slab is only supporting normal floor loads. Prior to pouring the concrete, a separating layer is placed on top of the Rockfloor boards and the Rockfloor should be placed on the DPM. An upstand of Rockfloor must be placed around the perimeter to isolate the floor slab thermally from the wall.
 
Screeded applications

The Rockfloor insulation is laid under the screed, which can then be the basis for any type of floor finish. The screed should be minimum 75 mm thick (minimum 65 mm for dwellings) and preferably of fine concrete. It should contain light wire mesh reinforcement and be laid strictly in accordance with BS 8204: Part 1.

The rebated Rockfloor boards allow non-anhydrite screeds to be laid directly onto the boards without the use of a separating layer. An upstand of Rockfloor should be placed around the perimeter to isolate the screed thermally and acoustically from the wall.
 
High performance screeds

Where thinner screeds are required, high performance specialist screeds may be applied above Rockfloor, but must be laid strictly in accordance with the screed manufacturer’s recommendations.
 
Anhydrite screeds

Anhydrite floor screeds are pump applied, self-levelling screeds. Often used for sub floor levelling, they provide an ideal smooth, flat surface to receive thin floor coverings such as tiles.

Anhydrite screeds, of a minimum 40 mm thickness, can also be applied as a floating construction over Rockwool Rockfloor (separated by a 250 μm gauge polythene membrane). This can significantly reduce installation time and offers floor to ceiling height advantages over traditional 65 mm thick sand/cement screeds.