Due to the nature of real wood such as oak it is a living and breathing product. It will expand and contract depending on its environment. A new wood floor looks fantastic but it is always best to ensure it stays looking pristine for years to come. The way to do this is to make sure the preparation for laying the flooring is done correctly, along with a common knowledge of the small issues that can happen with real wood flooring.
Solid flooring has a tendency to expand and contract. In summer, when the air is more humid due to the house being aired more often – the boards soak up the extra moisture and tend to expand slightly. In winter, when central heating / underfloor heating are used regularly, the air in the house is very dry therefore resulting in the boards drying and contracting – this often creates gaps appearing between boards – often large enough to put a coin between. These are harmless and disappear in the warmer months when heating is not used in the house as often.
When hardwood flooring gets wet or damp it absorbs the moisture and expands to accommodate this extra moisture. This can often happen even if the room does not feel damp or wet – the humidity in the air can also affect the floor. Before laying a wooden floor in is essential to check that the room is dry and the sub floor contains no extra moisture. It is also best to check the moisture content of the flooring before installing. However the sub floor is the most important thing to check before installing as this will affect the floor if it is not the correct moisture levels.
Where an existing timber subfloor is present, this needs to be checked for wet rot, dry rot and for woodworm. Although these are not commonplace it is always best to check existing floors before laying down your new wood floors which can get ruined by rot or woodworm. It is always best to ensure that the existing boards are also securely fastened to the joists as they will cause creaking if not fitted well. Loose timber boards can be screwed down onto the joists – or additional noggins can be placed between the joists if an old board has been cut in the wrong place and is loose.
When nailing down onto the existing flooring, the boards should be laid at 90 degrees to the sub floor. This ensures maximum stability and strength in the floor. (As an example consider a jenga game where all the blocks are placed on top of each other in the same direction – it is extremely unstable). If you are wanting the boards to be laid in the same direction as the sub floor a layer of plywood can be placed and nailed or screwed down to ensure a stable fit of the new wood flooring.
There are additional precautions to take where a screed or concrete sub floor is present. New concrete dries at a rate of 1 inch per month or 1mm per day. Although the concrete can look and feel dry to the touch, it can often still contain more moisture than the recommended amounts for hardwood flooring. The best way to check is to use a moisture meter – this will give you an instant reading and tell you whether you need to leave it to dry for longer.
If the new wood floor is engineered flooring that is being laid as a floating floor then it is possible to lay an extra layer of damp proof membrane (DPM) over the concrete / screed to ensure no moisture reaches the wood floor however if the floor is being glued down to the subfloor or battened out it would not be possible to lay the DPM, however a liquid DPM or epoxy resin can be used to create a liquid barrier instead. As solid wood floors are recommended to be stuck down to the sub floor it is best to glue solid wood floors down to the concrete directly therefore it is essential that the moisture is checked before laying.
With all wood flooring, an expansion gap must be left around the edge to ensure there is room for expansion in case of problems with moisture. This can be covered with skirting, beading or an edge profile. When preparation for the sub floor has been completed correctly, the laying of the wood floor is more likely to fit properly and without problems for the future.