The subfloor is the existing floor in your property. There are many types of different subfloors, including: joists, concrete, wooden floor boards, plywood, chipboard, asphalt and bitumen. Installation methods for solid wood flooring and engineered wood flooring differ depending on the type of subfloor. Before installing any hardwood flooring, ensure that the subfloor is flat, level and dry.
Joists
If you are laying hardwood flooring directly onto joists then the planks must be at least 18mm thick to ensure enough strength and stability. Either engineered wood flooring or solid wood flooring should be secret nailed or secret screwed directly to the joists.
Concrete or screed
If your subfloor is concrete (a screeded floor) then either engineered wood flooring or solid wood flooring can be used. Solid wood flooring must be glued directly onto the concrete. Engineered wood flooring can be floated over an underlay, without fixing it down, or it can be glued directly onto the concrete.
Wooden floor boards or Plywood
If your subfloor is wooden floor boards or plywood then solid wood flooring must be secured down by either secret nailing or secret screwing, with the flooring planks running perpendicular to the floor boards. Engineered wood flooring can be floated over underlay, or if the flooring planks are 18mm or thicker it can be secret nailed or secret screwed down.
Chipboard
A chipboard subfloor can be treated in a similar way to concrete. Solid wood flooring must be glued directly down to the chipboard. Engineered wood flooring can be floated over an underlay, without fixing it down, or if required, it can be glued directly onto the chipboard. Secret screwing or secret nailing should not be used as it will break the chipboard and the hardwood flooring will not have a secure material to hold on to. This will mean that the hardwood flooring will not be securely fixed in place.
Asphalt
If your subfloor is asphalt, a black smooth compound, which is fairly common for levelling and sealing concrete floors, then a primer must be used before the adhesive will adhere to it. Solid wood flooring must be glued directly down to the asphalt. Engineered wood flooring can be floated over an underlay, without fixing it down, or it can be glued directly down.
Bitumen
Occasionally a concrete subfloor will have bitumen residue, usually from old parquet block floors. If gluing solid wood flooring down then 95% of the bitumen residue should be removed. Engineered wood flooring can be floated over the bitumen.
