residential development guide for home extensions and new dwellings 



ARDEX SUB FLOOR SCREEDS -Building Materials and Architectural Building Products

Rapid hardening and drying cement for floor screeds. Used in place of Portland Cement in cement/sand screeds. ARDEX A 35 produces a floor screed that can be walked on after 3 hours and is dry enough to receive floorcoverings after 24 hours regardless of screed thickness or 4 hours when smoothed with ARDEX A 55.

After 1 day the compressive and tensile strengths of an ARDEX A 35 screed exceed the acceptable minimum attained by a conventional screed after 28 days.

Most home extensions requiring planning permission will probably benefit from using their products during the build.  Many Architects or House Extension Designers can incorporate their products within the scheme design drawings and specifications.

The following article may be of interest for homeowners researching this type of building product for inclusion within their own house extension scheme.

How to Lay Floor Screeds on Concrete Slab

Floor screeds on a concrete slab are laid when a developer has finished the slab concrete. This is after all other building elements are complete. Floor screeds are the layers of cement and sand mix laid onto concrete as a finish. This will allow for other floor materials like wood blocks, wood parquet, laminated timber, PVC tiles and ceramic tiles to be laid. The type of material to be added determines the screed to be laid. This can be smooth or rough using a steel or wooden float respectively.

The method used to lay floor screeds on concrete is to first hack the concrete to remove laitance. This the smooth cement substance appearing on concrete after casting. Once this is done a key is formed to ensure proper bonding of the new floor and concrete. The next thing is to wet the floor to prevent competition of absorption of water between the slab and screed. Pour cement slurry and rub it in to the slab to create a bonding agent between the two elements.

Mark levels for the floor screed either to give it falls or to run smooth on the concrete slab. Pour the cement and sand mix on the concrete surface. Spread evenly with a rake and pound with a rammer to give a hard surface. Level out the excess mortar with a straight edge and follow the marked out levels. Use a wood float until the surface has reached the required level. Remember also whether another finish will be added either wood parquet or PVC tiles. This will ensure the screed is finished rough with a wood float for ceramic tiles. However for PVC tiles or parquet, a steel float is used for addling the skimming coat on which to lay them.

A skimming coat is usually a mix of cement and water. This is applied with a steel float to make a smooth finish on the screed. It can be applied as final floor finish. This also allows timber finishes, rubber or carpets to be laid using adhesives. After deciding about the intended finish on the floor, lay the required smooth or rough finish to that materials specifications. Allow the floor screed to dry. Cure it continuously by wetting for about a week. When completely dry it is cleaned and the next finish like parquet added to finish off.