Acclimation, subfloors and expansion gaps — the parts of a floor installation you never see, and why they decide how the floor ages.
A wood floor is a natural material laid over a structure that is rarely perfectly flat, in a house whose humidity changes with the seasons. Everything in a good installation is about accounting for those three facts.
The wood sits in the house before it goes down
Wood takes on and gives off moisture until it settles at the humidity around it. Boards delivered from a cold van into a warm house are not yet at that point. Laying them straight away means they will do their settling after they are fixed down — which shows up as gaps in winter or as boards pressing against each other in summer. So they sit in the room they are going into, boxes opened, until they have caught up.
The subfloor decides more than the boards do
- It has to be flat. Humps and dips telegraph straight through to the finished floor and cause the boards to flex and creak underfoot.
- It has to be dry. Moisture from below will find its way into the boards.
- It has to be sound. Loose or squeaking boards underneath do not get better once they are covered.
The gap around the edge is deliberate
A wood floor is laid with a gap left at every wall. That gap is what lets the whole floor expand across its width in humid weather without lifting in the middle or pushing a wall. It is covered by the skirting or by a bead, which is why the trim goes on after the floor and sits on top of it rather than the floor being cut tightly around it.
Doorways, transitions and the tidy edges
Where a wood floor meets tile, carpet or another room, it needs a transition that hides the expansion gap and takes the change in height. Door casings are usually undercut so the flooring runs beneath them, which reads as a clean continuous line rather than as a floor cut awkwardly around a door frame. These details are most of what separates a floor that looks fitted from one that looks laid.
Afterwards
Keep the indoor humidity reasonably steady and the floor will stay steady with it. Felt pads under furniture, mats at the doors where grit comes in, and a damp mop rather than a wet one. Some seasonal movement is normal in a real wood floor — it is the material doing what it is supposed to do.
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