Moisture content for furniture and joinery: what values and why
What moisture content wood should have for furniture, stairs and external joinery. Why a wet board ruins a project and how to buy so as to avoid it.
The most expensive board in the world is no use if it is too wet. Wet wood carries on drying inside the finished piece of furniture, and that is when the customer starts calling: the worktop has lifted, the front does not close, a gap has appeared in the glue line. That is why moisture content is the first thing worth asking about when buying.
What values to work to
As a guide, for typical applications:
- furniture and elements in heated interiors: around 8–10%,
- internal stairs: similar, 8–10%,
- external joinery, cladding, decking: typically 12–15%,
- roof structures: in the region of ten-plus per cent, as per the design.
The principle is simple: wood should have a moisture content close to the conditions in which it will work. In a heated house the air is dry in winter, so the wood has to be dry too.
Seasoning is only the beginning
Natural seasoning, which with us runs from 6 to 24 months in a covered seasoning shed, brings the moisture content down to the low tens of per cent and, more importantly, does so slowly, without introducing stresses. To reach furniture moisture content, the material then has to be dried further. We carry out this drying for joinery and release sawn timber at a moisture content agreed with the customer.
How to buy without getting burnt
Tell the supplier what the material is destined for and ask for a specific moisture content figure, not for an assurance that "the wood is dry". A reputable sawmill will measure it with a moisture meter in front of you. With us that is standard, as is telling you which grading batch the board comes from.
Have a project and are not sure what moisture content to work to? Say in your enquiry what the wood is destined for. We will advise and prepare the material to suit your conditions.
Frequently asked questions
What moisture content should wood for furniture have?+
For furniture and elements in heated interiors, around 8–10% is the usual figure. For external joinery, correspondingly more, typically 12–15%.
What happens if I use wood that is too wet?+
The element carries on drying inside the finished product: it shrinks, warps and cracks. Fronts stop fitting, the worktop lifts in the middle and gaps open up in the glue lines.
Is naturally seasoned sawn timber sufficient for furniture production?+
Seasoning alone does not usually bring the material down to furniture moisture content. That is why, after seasoning, the material is dried further to the target value; at the Drewno Pilarscy sawmill we carry out this drying for joinery.