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Roof rafter length


Ktm250rider's Avatar
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Join Date: Jan 2001
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04-05-04, 06:42 PM   #1  
Roof rafter length

I am looking at house plans and trying to figure out how these things are built. We are currently looking at a cape with a total roof span of 52 ft., at 10:12 pitch. This includes 6 and 10 foot overhangs for a front and rear porch. According to my rough sketch, the rafter length will be close to 34 ft long. Would you have to splice two rafters to span the roof? I would assume at the knee wall. I suppose you could use a single I-joists but I was just wondering what they did before them.

 
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awesomedell's Avatar
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04-06-04, 05:50 AM   #2  
These days about 99% of the time roof trusses are built in a factory, trucked to the site & set up with a crane. Total crew on the site that day is 4-5.

By contrast, around these parts we have a fairly large Amoish community, when those folks get together for a house/barn raising there will be like 35-40 men there working as a team they get one framed up in a couple of days. However I once did the drywall in one of their homes, I think it's safe to say they never used a level or square. I don't bid work for them anymore.

 
A_unique_name's Avatar
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04-06-04, 12:54 PM   #3  
rafters

To calculate the length @ 10/12 slope take the horizontal span x 1.3017 and that will be the rafter length. If this is as long as you say then yes you are going to have to splice them together. If you can do this over a bearing beam or knee wall that is great. If not then you should consult with an engineering to design the connection of the members.

I would suggest I joists in this case. I doubt a typical roof truss will work for your application. If you are trying to keep the depth down that is.

 
coops28's Avatar
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04-08-04, 05:46 AM   #4  
Seems to me that your porch overhangs will be seperate from the roof framing anyway.

 
awesomedell's Avatar
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04-09-04, 07:46 PM   #5  
Of course there's that too, Coops.

 
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