Importance of moist measurements

Wood likes water as long it's a tree, after that......

Before installing a wooden floor, there are three important items you (must) check for moist:

1. The underfloor, specially if concrete/screed
2. The wood itself
3. The air in the room(s) you're installing the wood in

1) When working with a new concrete/screed underfloor there is a rule of thumb: every inch (2.5 cm) under normal circumstances takes 30 days to dry-out sufficiently. Under normal circumstances means: no forced drying with heath-canons and the room(s) are not exposed to the outside climate (simple meaning: all walls, windows, outside doors are in place ;-)
Ventilate as much as possible to assist the drying process.

The moist level in concrete/screed underfloors must not exceed 2.1%.

2) Always make sure your wooden flooring comes from a reputable source. The moist content in Oak flooring (90% of all flooring in the U.K.) must be between 9 - 11 % Storing the wood in the room you intent to install it in (2 - 3 days before the works start) is good practice: it will let the wood acclimatize to the specific conditions of that room.

Beware of cheap offers telling you the wood is kilned dried: this could mean dried as normal timber to 15% Since wooden flooring is (in the U.K.) still a growth market timber yards are trying to get 'a piece of the action', but compared to traditional flooring manufacturers with 50 - 100 years of experience in drying wood for flooring, some don't really have the equipment (or knowledge! )to dry to floors correctly. So buyer beware !

3) Wood will always react to moist (or lack of) in the air. Just think of doors in Spring or Autumn jamming in the door-frame. And that's just hardly a meter wide.
Most wooden floor installation instructions speak of installing the floor by an air humidity between 50 - 65%, but does that mean you can't install your flooring when it's lower or higher?
Well, ideally 50 - 65% humidity is the best (not only for flooring, but also for your own health), but there are many days during the year that the humidity is much higher or lower (think of Winter: central heating on full, dry wind causing your skin (lips) to dry-out).

What then?

If the humidity is low, allow for a wider expansion gap between the floor and the wall (or skirtingboard). This will give the wood more space to adjust to higher humidity and to expand without getting stuck to the wall (or skirtingboard). In extreme cases the floor will still expand beyond it expansion gaps and then the only thing you can do is to ease the floor by cutting a bit of the boards hitting the wall (or skirtingboard).
If you've taken care to allow for sufficient expansion gap and your floor starts to expand in a season were it normally shrink (wood works all year round), you might have a moist problem caused by leaking pipes or rising damp.

Remember: wood likes water as long it's a tree, after that......

For more tips and advice on wooden flooring see our DIY web site