I am putting up a second story in a small building I want to create a framework to carry the load of the addition. I'm putting in piers and posts, which I have found correct info for. I have a stock of lumber, 4x6's and 6x8's, I would like to use the 6x8's. They would be supported by the piers and posts, one exact set on each under side of structure. The total load they would carry is 4500 lbs. so two sets of, two piers and posts with 6x8 beam spanning 8'. Hope this is not too confusing! Lol Thanks for the help


I'm not sure I understand where the posts and piers are in relation to the 6x8's. However, I can give you some info and maybe you can interpret.

According to Western Woods Use Book by West Coast Lumbermen’s Association, 1973 edition, a 6x8 beam can support about 8,000 lbs., depending on species of wood, grade, etc. on an 8' span.

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  • Source or reference link? – isherwood Sep 27 '17 at 15:27
  • Western Woods Use Book by West Coast Lumbermen’s Association, 1973 edition. It has about 10 species of wood in various classifications , (I.e.: dimensional, timbers, posts, etc.) – Lee Sam Nov 4 '17 at 15:22
  • How is the load distributed? A point load at the center is worse than a uniformly distributed load along the length. – Jasper Feb 11 '18 at 2:34
  • Also, the fast-growing trees used for much of today's lumber cannot take the all of the loads that the slower growing trees used for 1973's lumber could. – Jasper Feb 11 '18 at 2:37
  • @Jasper Depends on the grade of wood. There are 5 grades of lumber for each species. Just because the tree is faster growing does not mean it won’t “take all the loads that slower growing trees.” Some species have a higher fiber strength and a greater modulus of elasticity. When it grew has little to do with strength...1973 or 2018. How and where it grew has a huge impact on strength...in a tree farm, warm climate, etc. – Lee Sam Feb 11 '18 at 3:24

Just went through something similar. You can check local building codes at city hall for that and more if necessary.

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