The first step is the same for sawn- and engineered wood materials: add up all the loads acting on a header or beam and then translate this load into terms of how much load each lineal foot of header or beam will feel. Here is a simplified approach that will help you specify the appropriate material for many applications. However, the process for sizing these structural elements can be complicated if you are not an engineer. The beam must be strong enough so it doesn’t break (Fb value) and stiff enough so that it doesn’t deflect excessively under the load (E value). ![]() The idea behind sizing headers and beams is straight-forward: Add together all live loads and dead loads that act on the member and then choose a material that will resist the load. ![]() They transfer loads from above to the foundation below through a network of structural elements. The job of headers and beams is a simple one. Part II will review sizing procedures, performance and cost of these materials for several applications (see “ Sizing Engineered Beams and Headers” for part 2). Part I will show you how to trace structural loads to headers and beams. In this 2-part series we will review how sawn lumber and these engineered materials measure up as headers and beams. Parallam, Timberstrand, Laminated Veneer Lumber and Anthony Power Beam are examples of alternative materials that provide builders with some exciting choices. Sawn lumber limits design potential and in some cases just doesn’t work. You can’t beat sawn lumber for most small window headers, but as spans and loads increase, stronger materials are a better choice. Too often builders gang together 2-inch dimension lumber to support roof and floor loads without considering other options. A neat solution, but is this an efficient and cost effective use of material? The same is true for beams like structural ridge beams and center girders. These headers work to support most residential loads and coincidentally keep the window tops to a uniform height. Most builders automatically choose double -2 x 8 or -2 x 10 headers to frame windows and doors in every house they build. Understanding how loads are transferred through a structure and act on structural members is the first step to sizing headers and beams Some information contained in it may be outdated. First world problems.Please note: This older article by our former faculty member remains available on our site for archival purposes. There's a 6 foot easement on that side to the fence, so the building wall will be reasonably close to the fence. OTOH, the north side where it will actually go did have the advantage that it could be closer to the "effective" line because the actual property line is about 7 feet into the neighboring property because of what had to be done when subdividing it years ago. It would be "logistically" and visually a lot better if it was on the south side rather than the north side but because of the required 15' side setback, a very large and mature willow tree would have to be destroyed. SWMBO is to not have the structure require removing any live trees. Positioning my own building has been an exercise because a "prime directive" for both myself and Professor Dr. Every property has its upsides and downsides. I'm sure that what you put up will meet the immediate need and you've mentioned that you do have a plan to move on in a few years to larger quarters. No way that would pass code now, but it's been there for 100 years and is still pretty straight. The funny thing i that the house is also 16 feet wide and has rough cut 2x4 rafters on 16" centers and a 12/12 pitch. If anyone knows of a rafter span table that goes up as high as 90# I would be very grateful to hear of it. It seems to me on a back of the envelope basis that full size 2x10 should be about right, but I am not an engineer. I think there is some extra strength in the full size rafters, too. It looks on the 70# chart like that would be okay, but I would need to go bigger for 90# presumably. They will be at 6/12 pitch, 24" centers and the span will be 8'9". I had specified full size rough cut 2x8 rafters on 24" centers. ![]() I would be happy to use whatever size rafters she told me to, but since neither of us knows what is sufficient I seem to be stuck unless I hire a structural engineer, which I would rather avoid if possible. ![]() The inspector also doesn't seem to know what size rafters are wanted. I can find rafter span charts for up to 70 psf, but nothing higher. The building inspector says that the roof must be designed for a 90 pound snow load. I have run into an obstacle in getting my workshop design approved.
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