Planning, process & cost
Subfloor preparation: the invisible half of a floor installation
You never see it, and it decides almost everything about the finished floor.
Nobody buys a floor for its subfloor, which is exactly why preparation is the stage most often trimmed to save money — and the stage most responsible for floors that creak, bounce, gap or lift. A floor is only as flat, dry and stable as what it sits on. Getting this right costs a day; getting it wrong costs the floor.
Flatness versus level
They are not the same thing. A floor can slope gently and still be perfectly flat, and a floating floor is far more sensitive to dips and humps than to a consistent slope. Manufacturers specify a tolerance over a given length — that is the target, and it is measured, not judged by eye.
Moisture testing
Concrete and screed hold construction moisture for a long time, and new screeds much longer than people expect. Laying a wood floor over a slab that is still drying traps moisture underneath. Testing before laying is the only reliable way to know.
Timber subfloors
Existing boards need to be securely fixed, with any movement dealt with before overlaying. Boards are usually overlaid with a sheet material to give a flat, continuous surface — laying directly over old boards transfers every unevenness into the new floor.
Acclimatisation and expansion
Flooring should sit in the room it is going into before it is laid, so it reaches equilibrium with the space. And every floating floor needs a perimeter expansion gap, hidden by skirting or beading. A floor laid tight to the walls has nowhere to go and will dome or lift.
Questions we're asked about this
About to have a floor laid?
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