Sub Floors & Preparation

A newly laid wooden floor will only be as good as the sub floor it is laid on, and will only perform properly if procedures are followed. It is therefore worth the time and effort to get your sub floor right. Turgon offer a detailed survey of your sub floor before we carry out any works, and we fully understand the wish to keep costs down on sub floors. However certain guidelines must be adhered to.

Concrete or screed

Concrete or screed floors must be level to within plus or minus 3mm over a two-metre span before any hardwood floor can be fitted. This applies whether you are floating the floor or sticking the floor directly to the sub floor. The screed must also be dry before attempting to fit the floor. The concrete/screed must according to British Standards 8201:2011 be allowed to dry to a maximum of 75% relative humidity before installation takes place, or 65% if you have underfloor heating. The sub floor must be tested before a hardwood floor is fitted. The British Standards compliant test involves placing a surface mounted humidity box for 24 hours. A simple surface tests will only tell you what is going on on the surface of the screed and not if the screed has dried out to any depth.

We do not recommend solid wooden floors over concrete.

 

Wooden: floorboards, ply or chip board

Wooden subfloors of any nature must be level to within plus or minus 3mm over a two-metre span, must be securely fixed and any rotten floorboards replaced prior to installation of a hardwood floor. It is also a good idea to test the moisture content of the wooden sub floor using a protimeter. The sub floor moisture content should be within 4% of your hardwood flooring to avoid over expansion or contraction.

Existing “Parquet Block” flooring is not a suitable subfloor for any hardwood flooring and must be lifted prior to fitting a new floor.

Floor joists or battens

As with any other sub floor, joists or battens must be level to within plus or minus 3mm over a two–metre span. The distances between the joists or battens will determine the amount of fixings that can be used (you can only nail where there is a joist). Solid floors must be fixed every 250mm – 300mm and 20mm engineered floors every 400mm. Most houses in the UK have joists that are 16 inches or 400mm apart.

If you are fixing a hardwood floor to battens on top of an existing concrete or screed sub floor, the concrete/screed must comply with the conditions stated above.