Almost every timber complaint I've handled — a warped door, a gap opening in a tabletop, a floor that squeaked by December — traced back to the same invisible cause: water inside the wood. Not rain. Not a leak. Just moisture the wood was carrying when it was cut, fitted or sold. Learn this one subject and you'll avoid most timber problems before they start.
What moisture content means
Moisture content (MC) is how much water a piece of wood holds, written as a percentage of its bone-dry weight. A freshly cut log can be over 100% MC — yes, it can hold more water than actual wood by weight. Wood is a sponge that happens to be solid.
A moisture meter tells you the number in two seconds. If you buy timber regularly and don't own one, buy one this week. It costs less than one ruined door.
Two kinds of water
Water sits in wood in two places, and they behave completely differently.
Free water fills the open cells, like water in a bucket. It leaves first when wood dries, and losing it changes nothing — the board stays the same size.
Bound water is soaked into the cell walls themselves. It only starts leaving after all the free water is gone — the point called fiber saturation, around 28-30% MC for most species. And this is where the trouble lives: every bit of bound water that leaves makes the wood shrink. Every bit it takes back makes it swell.
So remember one line: nothing happens above 28%, everything happens below it.
Wood never stops adjusting
Here's the part many people never learn: wood doesn't dry once and stay dry. It keeps trading moisture with the air around it forever, drifting toward a balance point called EMC — equilibrium moisture content.
In a humid coastal godown during monsoon, that balance might be 16-18%. Inside an air-conditioned Delhi flat in winter, maybe 7-8%. Move a board from the first place to the second and it will shrink — guaranteed, no exceptions, no premium species exempt. The only question is whether it shrinks before you fit it or after.
That's the entire logic behind acclimatisation: let the wood reach the moisture level of the room it will live in, then work it. Skip this step and the room will finish the job for you, on its own schedule, through your finished joinery.
The numbers to aim for
Different jobs need different moisture levels. Rough guide:
Indoor furniture and flooring in conditioned spaces: 6-9%. General interior work: 8-12%. Outdoor joinery: 12-16%. Construction timber: under 19%.
Ask your supplier for kiln-dried stock and check it yourself with the meter. "It's dry, sir" is not a measurement.
Three habits that prevent almost everything
One: measure MC when timber arrives, not after problems appear. Two: let wood acclimatise in the room where it will be installed — days for thin boards, weeks for thick ones. Three: always leave expansion gaps in floors and panels, because seasonal movement never fully stops, it only gets smaller.
Do these three things and you'll be ahead of most of the trade.
Using a moisture meter properly
A meter is only as good as the person holding it, so three habits worth forming:
Take readings from several boards in a stack, not just the top one — the top board has been drying in the air while the middle of the stack hasn't. Push pin-type meters in along the grain, and take the reading from the middle of the board's length, because ends always read drier than the heart of the board. And set the species on the meter if it lets you; the correction between a dense hardwood and a light softwood can be two or three percentage points, which is the whole difference between "ready" and "wait a week."
Work it out instead of guessing
The maths behind all this — EMC from temperature and humidity, shrinkage per species, acclimatisation time — is exactly what our free tools handle. Start with the EMC calculator, then the shrinkage predictor for your species. Two minutes of checking beats a callback every time.