Controlling Wood Movement

For centuries, freshly cut lumber has been allowed to dry in response to the temperature and humidity of the surrounding air, also known as the ambient conditions. But if the wood is left to season for a year in the woods, aromatic oils will dissipate; live tree wildlife will move out; and salamanders, centipedes, and other decaying-wood critters won’t move in, so the wood will be easy to live with. A tree that is cut down and left whole, or a standing dead tree, can actually dry quickly through the leaves. Other good safety tips include having your wood stove serviced, or at a minimum, replace your stove door gasket and have your chimney cleaned annually. The closer you can get the wood to equlibrium the more stable it will be once it’s in place.

If a fast drying rate generates forces greater than the strength of the wood, internal checks can form. I have brought lumber to my attic to help it dry out, and before I install flooring or paneling, I always let it sit inside for a week or two. Being sure that the wood sample or samples is, or are, truly oven dry requires patience and careful weighing using accurate scales. Their non-damaging pinless technology even lets you scan” many board feet of lumber to help identify potential wet spots or changes within wood stock or wood flooring.

If a piece of wood is too thick, the pinless meter will not be able to take a reading of the deepest layer of the wood. When the humidity of the air exceeds the level specified by the drying schedule, the warm, moist air is vented to the outside, and cool, drier air is brought in. Each time moist air is vented, all the energy from the boiler is also lost. Where the wet weight is the weight of the original ‘wet’ sample and the dry weight being the weight of the sample after drying in an oven. The time and costs associated with this practice must be considered by potential users before investing in drying facilities. I have seen other ideas for a homemade kiln but this incredible is by far the best!


You need to weigh the wood samples and I find electronic postal scales purchased at reasonable cost from an office supplier work well enough for my needs: if you require more accuracy then better, more expensive scales are required. The test is performed by cutting the sample to be tested, weighing it, drying it to a constant weight, reweighing, and doing the calculation. Seasoned wood is wood that has been allowed to dry long enough for the sap and cellular moisture to escape. Wood moves, swells and shrinks according to humidity, doesn’t matter whether kiln dried or air dried. Three or four handsome cylinders of wood out back are a much better use of space.

Lumber, usually dried in stacks called piles, should be properly stacked for either air drying or kiln drying. Segue Construction, the Library Gardens’ general contractor, was targeted in two lawsuits over alleged improper waterproofing of balconies that led to wood rot, in Millbrae and San Jose. It is 2 inches thick.I dont have access to a kiln and would like to bring it inside for some shelves etc. However, the EMC is as low as 6 to 7% in dry centrally heated houses and offices or in permanently air-conditioned buildings. As the dry air moves over the lumber, it evaporates the moisture from the surfaces.

When choosing a type of moisture meter for woodworking, take into account the size and shape of the wood you’re working with. Boric acid, or borate, is an excellent fungicide (a pesticide that kills fungi) against the dry rot fungus. Some wood stackers like to build a series of cubes like little blockhouses; others raise whimsical shapes. This reduces the total amount of moisture that needs to be removed from the stack, and ensures that if the drying process is slower than anticipated, I still have well-dried wood in the center. This core will then begin to dry and shrink, however any shrinkage is resisted by the already ‘set’ shell.

Depending on climate and conditions of storage, normal firewood won’t dry down to kiln-dried moisture because of normal outdoor humidity. Fused borate is often used to protect log ends in log homes (see Protecting Log Homes From Insects and Dry Rot ) and wood utility poles against dry rot. Kiln operators can make instant changes on the touch-screen interface integrated with each individual kiln. Dimensional stability of wood flooring refers to how a floor moves” once it is installed.

I added a couple of remote sensors in the middle of the stack so I could tell when the wood was dry without having to open the kiln (Photo 5). I used a commercial kit (see Sources, below). To minimize the changes in wood moisture content or the movement of wooden objects in service, wood is usually dried to a moisture content that is close to the average EMC conditions to which it will be exposed. Moisture will move from an area of higher moisture content to an area of lower moisture content within the wood.