Stage 3...Rafters - Carpentry - DIY Chatroom Home Improvement Forum

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Old 08-18-2006, 12:34 AM   #1
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Stage 3...Rafters

OK I am a beginner and a slow learner on my patio roof addition. The first step was identifying the beam span. Didn't get the OK for Western Red Cedar 4" x 12" for span load so I went with Parallam (how sad). Next was the footings tables, i.e. frost line at 18" minimum, 1 meter (40 " square x 8" thick (into clay no less). Finally completed.
My last challenge requires help from someone out there please.
I have my roof size, column locations and centerlines, etc.
I will be using 2x6 rafters with 4/12 pitch on 24" centers. I will also be sandwitching these with double 2x4 on either side. I can't seem to find a book on typical rafter framing examples and as such I don't know if I need vertical supports anywhere.
Can anyone help me with the basics on this. I've attached a zipped PDF of the plan if this helps... Help.
Attached Files
File Type: zip Patio cover (25.9 KB, 73 views)


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Old 08-19-2006, 12:56 AM   #2
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You don't need verticals anywhere in the roof structure. As far as I can see you don't need doubled 2x4's either, one at each rafter position would do, but whatever. The 2x4 keeps the walls from spreading, the rafters push against the walls and each other. You're good to go!


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Old 08-19-2006, 10:14 AM   #3
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Sandwhiched rafters

Thank you for the answer on the verticals. Much appreciated.
I had originally planned to sandwhich the rafters for effect since the underside was to be completely open. After giving in to the parallam for beams over the 4x12's I've come to realize it's not going to look that great anyhow so I may drop the double 2x4.
Any thoughts on how to insure the beams are level. I'm not sure how well a standard 3' level is going to be over the 17' beams?
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Old 02-02-2008, 09:04 PM   #4
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Nice design drawing. I designed, permitted and built similar patio cover although my total width was 20' and used 4X6 rafters on 24 centers with t&g roof sheeting and it looks really nice. I think my rafters were around 12 feet. My ridge beam was 4X12 and 14 feet long and my base (anchor) beams were 4X10s. I also used 3 10" resin columns with threaded rod from concrete to top of beam and that really made it stand out. The only vertical support is at the inside and outside beam that is a 4X4 up to the ridge beam and also a double 2X4 to the ridge beam to catch the 2x10 ledger attached to the house. The difference in my design is that I have a center column on the outside beam. I lag bolted each rafter to the outside beams and used 4X6 spacers ripped to match the roof line. I have all my design and approved plans along with a patio cover design guide provided by my city building dept. Covers spans and lumber but is focused on lean-to type covers.

I think you would be happy with the look of the 4X6 rafters and you can skip the sandwich 2X4s. Good luck with you design. Mark

I'm now going to use a Parallam for a 17.5' span in garage to finish off attice (3.5x11.25).

Last edited by Mablamb; 02-02-2008 at 09:25 PM.
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