9/27/2017 0 Comments 2X6 Pressure Treated Weight LossA fundamental fact is that wood is hygroscopic. This means that wood, almost like a sponge, will gain or lose moisture from the air based upon the conditions of the surrounding environment. But not only does wood gain or lose moisture, but it will also expand or contract according to the magnitude of such changes; and it is this swelling and shrinking in finished wood products—often referred to as the wood’s movement in service—that is responsible for so much mischief and so many malfunctions in woodworking. When a tree is first felled, it is considered to be in the green state, and contains a very large amount of moisture. This moisture exists in two different forms: as free water that is contained as liquid in the pores or vessels of the wood itself, and as bound water that is trapped within the cell walls. Once a fresh log or piece of lumber is cut and exposed to the air, it will immediately begin losing free water. At this point, the wood does not contract or otherwise change in dimension since the fibers are still completely saturated with bound water. It is only once all the free water has been lost that the wood will reach what is called the fiber saturation point, or simply FSP. Below the FSP, the wood will then begin to lose moisture in the form of bound water, and an accompanying reduction in the wood’s volume will occur. At this point, the wood is no longer considered to be in the green state, but is now in a state of drying. Just how much bound moisture is lost during the drying phase will ultimately depend upon the temperature and relative humidity (RH) of the surrounding air. Many Things Add to Upgrade Cost. Depending upon the size of your home, the cost to upgrade from 2x4 to 2x6 exterior walls can be significant. I decided to make a list. How do I find an answer to an Email question? I answer the questions all kind of ways. Farmstead Raised Garden Beds are based on a 17th century design. Handcrafted of Vermont White Cedar, these raised beds will last for many years and weather to a soft. Weights of green, kiln dried and pressure treated lumber boards. Perhaps the most important aspect of woodworking deals with the relationship between wood and moisture. A fundamental fact is that wood is hygroscopic. At 1. 00%? rh, no bound water will be lost. 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. The amount of water in a given piece of wood is expressed as a percentage of the weight of the water as compared to its ovendry weight. 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 1. Moisture Content % = (weight of water / ovendry weight of wood) x 1. For instance, suppose that a freshly sawn piece of Eastern Cottonwood (Populus deltoides) weighed 5. So using the equation above: 3. In most practical circumstances, the easiest way to check the moisture content of a piece of wood is to simply use a moisture meter. But it’s a good practice to understand what the moisture meter reading actually represents, and to recognize that readings above 1. MC are possible, (and in the case of many lightweight species in their green condition, are quite common). As a piece of wood dries, it first loses its free water and dips below the FSP (fiber saturation point). This FSP corresponds to roughly 3. MC in most wood species. A moisture gradient develops where the outside (shell) is drier, with the interior (core) still wet and playing catch- up. As the MC of wood drops below the FSP, it will continue to lose moisture until it eventually stabilizes at a value that is commensurate with the surrounding moisture in the air. This is known as the point of equilibrium moisture content, or simply EMC. The EMC will change based upon the fluctuating temperature and relative humidity of the surrounding air. In addition to the fundamental fact that wood is hygroscopic, perhaps the most crucial concept to understand regarding wood and moisture is the link between relative humidity and equilibrium moisture content. From studying the included chart, several important points pertaining to the relationship between relative humidity (RH) and equilibrium moisture content (EMC) emerge. The chart tops out at 3. EMC, which is equivalent to the FSP. 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. The plotted line is not flat (linear), and 5. RH is not comparable to the midpoint value of 1. EMC. This means that wood will swell to a significantly greater extent if it is exposed to prolonged humidity in excess of 8. RH. Conversely, the line is somewhat flatter in the range of 2. RH. Humidity changes that happen in this window have a slightly gentler effect on EMC, and hence results in smaller amounts of shrinking and swelling. Although the values given in the preceding chart are for rh at 7. Exterior values can be much more variable depending on locale and season, but averages typically range from 3. RH, corresponding to 6 to 1. EMC. It can be very useful to make mental notes of common humidity levels and their corresponding EMC. For instance, furniture and other interior woodwork should usually be constructed with an intermediate target of 8% EMC, which is achieved by storing lumber at approximately 4. RH. For exterior projects, a target of about 1. EMC is a good compromise, which equates to lumber stored at 6. RH. Using lumber that is within the median EMC range for a given locale prevents the Goldilocks syndrome: the wood is not too dry, (which might lead to subsequent swelling in the humid summer), and not too wet, (which might lead to checking and splitting in the dry winter). In this way, the wood is most likely to remain as close as possible to its intended size and shape. Related Articles. Diabetes Id For Men Herbal Viagra Does It Work with Male Enhancement Shots Location and Herbal Viagra Does It Work. If I understand you correctly, you have four posts in the garage. You indicate that the four posts support two 2. This suggests two posts per beam, which would place the posts 2. Elsewhere you indicate that the beams are 1. I could not tell how wide the garage is, perhaps 1. At any rate, the load bearing capacity of an 8 foot long post is most probably controlled by buckling, not by axial compression. In axial compression, wood is typically good for at least 1. However, the post will typically buckle under much lower load than the axial compression. Computation of allowable load where buckling controls is not simple, and there are typically not tables in the code books as there are for beams under horizontal bending. The difficulty in computing allowable buckling load is determining the end conditions. If the post is fixed on both ends, it buckles at a much higher load than if one end is free or pinned. Similarly, if the post is restrained in the middle, it buckles at a much higher load than an unrestrained post. For an unoccupied garage, total vertical load is typically relatively small, however you indicate that you have occupied space above the posts and beams, so it would be prudent to have an engineer check the capacity of the posts, especially since it sounds like the ones you have in there have either buckled or warped severely. Living space adds considerably to the load on the posts, especially if the posts are carrying all the load, and the exterior walls are not load bearing. How can i immediately lower my blood pressure. COMING SOON ON FACEBOOK. Coming soon to the internet's top social site Facebook! Check back soon to follow us and connect with our community members.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
November 2017
Categories |