A little old lady wants me to build a cover over her 2nd story deck, approx. 16 long by 10 deep. She drew up the plans supporting the two outside corners with 4 X 4s and the rear rim joist bolted to the house under the eaves. She visualized using 2 x 6 x 10 for the rafters, attached to a doubled 2 x 6 x 16 with a steel flitch plate bolted between them for rigidity. The roofing material is to be a PVC sheet product she described as Palruf PVC. It sounds to be a lightweight transluscent panel. She says it is not corrugated. She is spacing the rafters 16 OC using saddle hangars. I told her that the flitch plate will probably be rather expensive and I dont know for sure where to purchase it. She would prefer not to have a support post in the middle of the front rim joist. Could just a doubled 2 x 6 span 16 in this installation without sagging?
Will This Sag?
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Doubled 2 x 6 will sag on a 16' span. Usually the distance of the span will dictate the width of the beam therefore a 16' span will require a 16" wide beam or a 4x16x 16' or 4x 18x 16' beam. Now-a-days the lumber/beams are cut from young trees and do not have the strength like old growth lumber/beams. I have seen 4x20 beams sag on a 20' span, they don't have the carrying power like before. Or you can go with an engineered beam/truss for the span and weight it will support. I'm not a structural engineer, just my opionion/experience building homes. I would have the lady consult an structural engineer for this before taking the job and risk having a recall. -
I take it you guys don't need building permits in Alabama?
Originally posted by jabeI would have the lady consult an structural engineer for this before taking the job and risk having a recallLast edited by 91FE; 09-15-2006, 07:04 AM.I like Wagoneers too. Hey...they've got woodComment
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my old 2 story deck is made of either 2x10 or 2x12 framing spaced 24" on center. The largest unsupported span is 12foot and it doesn't sag with with 5/4 decking on top of it. This deck is nearly 20 years old.
I think for what she is trying to do (minimal weight load, no snow) 2x10's would work. 2x6's might sag a bit.Mike
Lakota's Dad
If at first you don't succeed, deny you were trying in the first place.Comment
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@x6 will indeed sag. I would go with a minimum doubled 2x8 with good crown. 2x10's are actually more expensive than 2x12's most places. 2x12's are very heavy and may sag some too. I think the best bet, since the roofing is so light, is to go with doubled 2x8. I have a doubled 16' 2x8 span accross my living room that I built. No sagging after 10 years so far.
You do need a permit for some things. This would be one of those things, unless there was an existing roof.
Getting a permit is just a matter of submitting a drawing of your intentions in this case. Then pay for it. All done in about 30 minutes where I live.LeeComment
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