How long does flooring need to acclimatise, and does it actually do anything?

The purpose is not to warm the boards up. It is to bring their moisture content into balance with the air they will spend their life in, so that they have finished moving before they are locked into a floor. That only works if the air in the room is the air the floor will actually live in, which is why the step is so often done pointlessly.

Step by step

1. Get the room to its normal conditions first.Heated to normal living temperature, plaster and screed dry, windows closed, ventilation normal. A floor acclimatised in a cold building with wet plaster will shrink dramatically once the heating goes on.
2. Bring the packs into the actual room.Not the garage, not the hall, not the van. The room the floor is going in, because that is the microclimate that matters.
3. Lay the packs flat, not on edge.Stacked flat, spaced with battens if the manufacturer asks for it, and off a cold or damp floor. Packs stood on end bow.
4. Follow the manufacturer's instruction on opening.Some products acclimatise in sealed packs, some require the packs to be opened, and a few — most notably some LVT and vinyl products — are specified as needing only a short period and no opening at all. The instruction differs and it is not guesswork.
5. Give it the stated period.Typically it is measured in days rather than hours for wood-based products, and longer for solid wood and wide boards. Longer than stated does no harm as long as the conditions are right.
6. Understand why solid wood needs it most.Solid timber moves most with humidity, engineered wood much less because of its cross-bonded core, laminate less again, and LVT hardly at all in humidity terms though it does move with temperature. The acclimatisation requirement follows that ranking.
7. Do not acclimatise into a building still drying out.New plaster, new screed and a recent flood all put an enormous amount of water into the air. Flooring that reaches equilibrium with that air will shrink hard afterwards, and the gaps that open are permanent.
8. Commission underfloor heating before, not after.Where there is UFH, the manufacturer's sequence is usually to run the system up and back down to a specified fitting temperature before the floor is acclimatised and laid. Skipping this is a common cause of gapping in the first heating season.

Common mistakes

• Acclimatising in an unheated room in winter and then turning the heating on — The boards equilibrate to cold humid air, then dry and shrink hard once the room is heated. This is a leading cause of gaps appearing between boards in the first winter.
• Stacking packs on edge against a wall — Boards bow, and a bowed board will not lay to a straight row. Flat stacking is part of the instruction, not an afterthought.
• Treating acclimatisation as optional because the floor is going down tomorrow — It is a stated condition of most flooring warranties. Skipping it is not just a technical risk, it is a warranty question if the floor later cups or gaps.

Questions people ask