carport/deck/freespan

[joemcc]

I want to build a freespan carport with a waterproof deck for the roof, 20 feet by 20 feet, attached to a two story garage on one end and  4, 6x6 posts with a header on the other end, 8' tall posts. The most snow we get around here is 6 inches at a time every 2 or 3 years, I am thinking of doubling up the joists on each end and two more sets at equal widths (from the garage out to the new beam)  with single 12 inch centers every where else, 2x12 standard lumber with 3/4" plywood deck, rolled roofing and outdoor carpet over that. From what I have seen using a 40# live and 10# dead this should be ok. If I have to I will add a beam at mid span but I would like it to be clear span, no center post, can anyone tell me what size that midspan beam would need to be if I set a post at each end? I am not sure if the load is correct at 50# Or will the 2x12 idea work with 20 foot span total? Thanks for any info.

[peg_688]

Use a glue lam , or paralam , LVL beam . Have a good lumber yard size it for you not a home center.

The biggest hurtle's I see are racking and up lift. Thats a big sail your talking about.

You could and should IMO use

  #1: over sized footing / concrete pads under the post with substancal hold downs inbedded into the concrete  

  #2: Substancial post to beam connectors .

  #3: Large hurricane clips , H 10 or larger.

  #4: Solid blocking over the beam between joist.

  #5: Lag bolts into studs on the ledger back at the building your tieing into.

  #6: Large 45 degree anti racking / bracing thru bolted at the beam and post connection . One off each side of the post.

That a start , of course a engineer / permit if required , etc should be concidered.

 Oh ya nail the snot outta the sheathing 4 " OC every where with 10 d galv nails.

There thats a better start.

G/L PEG