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Once again, I come to ask advice. I am doing some remodeling for a guy who has a typical Interior Alaska shack, built in ten stages with recycled materials and a minimum of expertise. Last summer he paid a lot of money for some guys to come in and retro the foundation, put his entire place onto a network of steel beams, etc. On one side of the house, three steel beams extend out in a massive cantilever to create a 9′ by 13′ platform. I have built a water shed (lean-to style) on this platform, which holds a 1200-gallon water tank. The guys who did the foundation promised him that the beams would hold the weight, but I have told the owner that he should hold off on filling the tank until he gets some professional advice on whether it will support the weight. So, I’m asking for advice.
Specifically, the beams in question are 34′ in total length. The cantilevered portion of this is 10′ (i.e. there is a support girder at the 24′ mark, then nothing). Furthermore, halfway along this 10′ cantilever (i.e. at the 29′ mark), the main beam ends and they welded on an additional 5′ chunk of beam to extend it all the way out. The beams are 6″ deep, 6″ flange, 1/4″ steel for flange and web. As I said, there are three such beams that support a 9’x13′ platform- the edge of the main house comes down about a foot beyond the start of the cantilever. The floor of the shed is 2×12. Given the weight of the shed (2×6 24OC, 2×8 roof, metal roofing), the water (1200 gal x 8 lbs./gallon= 9600 lbs.), and especially the weld, I foresee disaster if the cantilever is not supported from below. What do you all think? I realize this might be confusing, I can submit some artwork if that would help.
Thanks,
Olav Ormseth
Fairbanks Alaska
Replies
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The steel used would be a W6x20. By the way you have described it, I would say this is fine. However, this is a question that only an engineer in your specified county can answer. If the plans were originally approved by the county then it has to have a stamp. The weld could be inspected by an engineer also to make sure it properly done for this application. Is the weld the only type of connection? What size beams hold the W6x20's up?
There are several other factors also. Again I'd say that this is fine, but I can't (nor can anyone else besides a local engineer) tell you for sure.
Billy
*Some artwork would be good. Please send it. No one can still say for sure but we can at least give an opinion from that.Billy
*I don't think you'll get too many responses for this one. Structural situations are a touchy subject around here. I'll talk to my stress people (engineering goons!) tommorrow (Friday) and see if I can come up with some answers for you (good or bad!). I think I understand the layout but I'll check back tommorrow to see if you posted a pic. Until then...In any case, you should have someone qualified in your area to look at it.CM
*As I remember interior Alaska, the building dept. and codes official is let the buyer beware. I don't think I'll stand under it.
*with a cantileve like that i would worry about to much deflection when the tank is full. a W6 is a very small beam. is the beam 50ksi or 36ksi steel? also sheer is a consern when cantilevering out that far.I would definatly get a engineer to check it.If this job isnt stamped buy a engineer then i would stay clear from it.
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Once again, I come to ask advice. I am doing some remodeling for a guy who has a typical Interior Alaska shack, built in ten stages with recycled materials and a minimum of expertise. Last summer he paid a lot of money for some guys to come in and retro the foundation, put his entire place onto a network of steel beams, etc. On one side of the house, three steel beams extend out in a massive cantilever to create a 9' by 13' platform. I have built a water shed (lean-to style) on this platform, which holds a 1200-gallon water tank. The guys who did the foundation promised him that the beams would hold the weight, but I have told the owner that he should hold off on filling the tank until he gets some professional advice on whether it will support the weight. So, I'm asking for advice.
Specifically, the beams in question are 34' in total length. The cantilevered portion of this is 10' (i.e. there is a support girder at the 24' mark, then nothing). Furthermore, halfway along this 10' cantilever (i.e. at the 29' mark), the main beam ends and they welded on an additional 5' chunk of beam to extend it all the way out. The beams are 6" deep, 6" flange, 1/4" steel for flange and web. As I said, there are three such beams that support a 9'x13' platform- the edge of the main house comes down about a foot beyond the start of the cantilever. The floor of the shed is 2x12. Given the weight of the shed (2x6 24OC, 2x8 roof, metal roofing), the water (1200 gal x 8 lbs./gallon= 9600 lbs.), and especially the weld, I foresee disaster if the cantilever is not supported from below. What do you all think? I realize this might be confusing, I can submit some artwork if that would help.
Thanks,
Olav Ormseth
Fairbanks Alaska