I am replacing a patio roof with an open trellis, 10′ rafter span, 20′ beam span with two 4×4 cedar posts to support the beam, 2×4 rafters, 12″ o.c. and 2×2 cross pieces, 12″ o.c. Other than the posts, all framing materials are treated SYP. The rafters will be attached to the dwelling fascia and rest on top of the beam. At present, my plan is to hang four 10′ 2×6’s on opposite sides of the posts, butt join them in the center of the span and attach a 10′ long “spline”, constructed of two 10′ laminated 2×6’s with a plywood center. The existing patio roof has 2×6 rafters, 24″ o.c., covered with plywood sheathing and roll roofing, and has three 4×4 posts supporting a 4×4 cedar beam that rests on top of the posts. The owner wants to replace the existing end posts and omit the center post altogether.
My two questions are: 1. Will this beam construction have noticeable deflection? If not, would lag screws or through bolts be better for joining the spline and the butted 2 x 6’s? Treated 20′ 2 x’s are not available. 2. Or should I step up to untreated 2×8 20′ framing boards? I plan to case the beam on four sides with cedar boards and believe I can waterproof the enclosure. Thanks for any advice. Zbalk.
Replies
If I read this right, you are spanning 20 feet with a bunch of stuff cobbled together?
Sure, it'll deflect. Look for 20' long 2x12s
Excellence is its own reward!
IF YOU DON'T HAVE ROOM HEIGHT WISE FOR THE 2X12'S ETC. TRY AN ALUMINUM I BEAM WHICH YOU COULD WRAP WITH WOOD (CEDAR OR?)..6-7" TALL ALUMINUM I-BEAM WOULD CARRY IT.
NO NEED TO YELL!
I can hear you just fine..
Excellence is its own reward!
Now that was funny!Any jackass can kick down a barn, but it takes a carpenter to build one.
Gee, I didn't mean to be phunny. I just figure if a guy's gota good idea, it'll take root and grow into a big tree until folks notice it. No need to shout and yell like a hurricane. They get attention in the worst way. But I've never seen a hurricane build anything..
Excellence is its own reward!
Truss Joist has parralam beams in various sizes available in treated. They're not cheap, but you only need one, right. A good dealer can help you size the beam for the loads involved. Good luck.
Brudoggie
Let me get this right? You are currently spaning 10' with a 4x4 beam made out of cedar which is not structural and shouldn't span more than 4'? Now the homeowner wants you to eliminate another post?
First of all use a hem/fir post not cedar. A gluelam would work for a 20' span but a metal I beam would not have to be as tall.
Are you building an Trellis or a roof?
I plan to case the beam on four sides with cedar boards and believe I can waterproof the enclosure
Do not splice your bean run.
"Rather be a hammer than a nail"
Bob