Understanding Moisture Content And Wood Movement

Expected movement can be accurately predicted, which means avoiding potential problems down the road. Using the right meter for wood can pose a different set of challenges from concrete. In this article I’ll share my experiences with drying wood, moisture content, and using wide lumber in a project. Humidity in unheated areas fluctuates about 10%, and while in service wood movement is low, dry material (6% MC to 8% MC) installed in unheated areas swells significantly. Simpson and Tschernitz 1 have developed a simple model of wood drying as a function of these three variables. Testing the flooring before installation gives you a good idea of what happened to it since it left the warehouse. Every region has an equilibrium moisture content (EMC) value or range of values.

The sponge’s physical dimensions will change each time it absorbs and releases moisture. It not only slows moisture transfer, but it ensures even transfer between the top surface and underside of the wood panel, keeping it balanced. In a living tree, those pathways function to move moisture and nutrients from the roots to the branches and leaves of the tree. At 0% RH, all the bound water in the wood will be lost, a condition known as ovendry—so-called because a kiln or oven is typically required to completely drive out all moisture. Essentially, you need to know there are two basic types of wood meters: pin and pinless.

In extreme environments, consider using cabinet grade plywood for wide panel application instead of solid wood. Any completed wood project or product can be jeopardized by moisture imbalances in the wood used. When a tree is first felled, it is considered to be in the green state, and contains a very large amount of moisture. Wood chip is of high-quality if its moisture content is 25-30 %. The table illustrates the effect moisture content has on energy content. For added convenience, some manufacturers offer models with both wood and concrete moisture meters combined into one.

In this article, we’ll explain the importance of understanding wood movement, how to use a moisture meter to measure the moisture content (MC) of trim, how to decide when a load of trim should be rejected, and how to accurately estimate how much trim will move after it’s installed. This won’t effect the fit of the door, but if the door finish is applied at the MC noted, there will likely be unfinished wood exposed as the door panels shrink to their in service width.

An appropriate moisture content for most species is usually between 7% and 11%, but can be slightly higher if the wood will be used for an outdoor project. These have an energy content (referred to as the net calorific value) of 3,700 kWh per tonne of wet chips. The base is installed first, and the flooring is installed scribed tight to it. In spite of what your lazy or ignorant flooring guy says, there is no gap, even after years of fluctuating humidity, and repeated sanding or scraping. With condensers, the efficiency can be further increased; but, for the normal stove, the key to burning wet wood is to burn it very hot, perhaps starting fire with dry wood.moisture content of wood

Although it will slow transfer of moisture; a finish will never stop it completely. As soon as wood is delivered, it begins to acclimate to the surrounding environment. For some purposes, wood is not dried at all, and is used green Often, wood must be in equilibrium with the air outside, as for construction wood, or the air indoors, as for wooden furniture. A carefully-worded disclaimer regarding wood movement would seem to be in order. Once the tree is felled, those pathways begin to lose that moisture as the wood dries.

While our furniture will not be structurally damaged by the normal range of moisture contents, you may notice some effects. Damage from shrinkage is not a problem here, and the drying may proceed more rapidly than in the case of drying for woodworking purposes. Only after you understand how and why solid wood expands and contracts can you take your woodworking to the next level. Ideally, the moisture content of wood should not change more than 2% when put into use. Some species of trees, when they are initially felled, may contain more water by weight than actual wood fiber, resulting in a moisture content (MC) over 100%. Testing both concrete and wood with one type of meter produces incorrect readings.

And despite what you may think, moisture gain or loss does not stop when temperatures fall below freezing. No matter where you are or which product you’re installing, controlling moisture on every job site is critical to avoiding those 95 percent of wood floor problems. Actors in wood trade should recognize the benefits which are gained when dry wood is sold instead of moist wood. Timber can be dried to any desired low moisture content by conventional or solar kiln drying, but in air drying, moisture contents of less than 18% are difficult to attain for most locations. In this way, the wood is most likely to remain as close as possible to its intended size and shape.

Remember, even after lumber has dried it still absorbs and releases moisture with changes in the relative humidity. Wood is hygroscopic, which means its MC will fluctuate based on the relative humidity (RH) of the surrounding air. When you’re shopping for hardwood flooring in Calgary, be sure to have the moisture content tested before you buy. Short of physically submerging a piece of wood underwater, it’s not possible to go back and exceed the FSP once all the free water has been lost.

For woodworkers and carpenters, the EMC is more helpful than RH. The simplified chart to the right shows the EMC values of wood when stored at the humidity and temperatures indicated. If wood movement becomes an issue, it’s important that you document delivered MC so that site acclimation compromise the readings. With accurate and current wood moisture content measurement, the flooring can be installed with assurance and finished for long-lasting and durable use.