DEAR POLE BARN GURU: I am building a pole barn 50 foot clear span wide, and 70 foot long, 16 foot to the eve. I am using 4×4 metal uprights on 20 foot spans, red iron purlins and stringers, and 4×4 metal welded all around the top. I am using conventional wood trusses engineered for my area on four foot centers. My question: Are the 4×4 square tubing uprights on 20 foot centers, with welded 4×4 square tubing around the top for the top plate heavy enough for this large of a building? Thanks, FLOYD in KIM
DEAR FLOYD: You asked for my honest opinion – here it is. I wouldn’t stand under or near your building as proposed in a wind or snow storm. With a 30 psf (pounds per square foot) roof snow load and a 100 mph design wind speed under the 2009 IBC (International Building Code) you are talking about some significant loads to be dealt with.
My best recommendation is to spend the money to have your proposed design reviewed by a RDP (registered design professional – engineer or architect) who can make the necessary revisions so you can end up with a building which will actually stand up under the imposed loads.