Wood and the Dog Days of Summer

The pet days of summertime are right here. Humid and sticky, but my wooden ground appears to be like fantastic! Each hickory flooring strip is pressed tightly from its neighbor. I know this will improve. In just a handful of months, gaps will form together the lengths of the exact floorboards. You see, wooden is a water loving content. Wood will achieve or loose moisture as the relative humidity alterations. Wood moves, and it moves a large amount!

Let’s start off with an instance tree this sort of as a sugar maple. When we harvest a sugar maple from the forest, the logs have a terrific offer of drinking water. When these logs are sawn into lumber, the resulting lumber is also incredibly soaked. The lumber will have all-around 70% dampness written content. This suggests that the weight of the water in the board is 70% the excess weight of the oven dry board. Oven dry means all water is taken out from the board. Some trees species have dampness contents higher than 100%. This signifies that the excess weight of the h2o in the board is higher than the bodyweight of the oven dry wooden.

To be ready to use lumber indoors, we need to have to take out most of the water. By removing water, we make the lumber more practical. Dry lumber is not palatable to most bugs or decay fungi, it is lighter, it is more robust, it glues greater, it holds screws and nails better, and it is more dimensionally stable.

Lumber producers in Wisconsin use lumber dry kilns to clear away water from lumber. If you have at any time driven by a sawmill, you may well have observed massive dice-like buildings, normally related in lengthy rows. These are lumber dry kilns. A standard kiln will maintain 40,000 board ft of lumber, and it will choose about 10 times to dry one particular inch thick sugar maple lumber from 70% down to 8% dampness material. 8% humidity articles is the business common for hardwood lumber made use of in inside programs. A species like crimson oak is additional tricky to dry and will get up to 30 times in the dry kiln to attain 8% humidity information.

A person typical misperception held by numerous is that after lumber is dried to 8% dampness material, the humidity content material stays at 8% and hardly ever changes. As a wood scientist and a wood worker, I know this is not the scenario. In point, wooden is a water loving material. You have read the term hydrophobic, which refers to a human being that is frightened of the h2o or a substance that repels h2o. Wood is just the reverse. It is classified as hydrophilic where by drinking water molecules will readily bond to the wooden substance.

Again to the lumber dry kiln, suppose we have a charge of sugar maple lumber that was dried to 8% humidity articles. If we take out it from the kiln and place it in a drop, what will come about if the weather is extremely humid? H2o vapor in the humid air will bond to the lumber bit by bit boosting its dampness material. What will come about if we ship the lumber to a very dry environment like the Las Vegas dessert? The lumber will give up h2o to the air lowering its humidity material. As a drinking water loving product, wooden will both attain or drop moisture primarily based on the relative humidity of its atmosphere.

I claimed at the beginning that wood moves a ton. What I intended was that wooden shrinks as it loses moisture, and swells as it gains moisture. Let’s go back again to the hickory ground in my living room. The boards are tightly fitted throughout the humid days of August. Humid summer time air causes the boards to swell, but not for lengthy. When the fuel furnace begins managing this drop, the relative humidity will fall, and the hickory floorboards will give up drinking water molecules to the air shrinking in thickness and width creating the gaps to sort. These gaps are specifically obvious close to the heat registers exactly where heat dry air blows immediately on the edges of the flooring.

Your challenge this week is to seem at the woodwork in your house and make a mental observe of the joints. Revisit these joints in January. How do you feel they will transform?