# Building A Tin Roof Over Existing Deck



## TheBug (Feb 2, 2009)

I have a deck that is on the back of my house. It's built just above the ground less than a foot high. I'm going to build a shed-type roof over it by running rafters from the house to a 2 x 6 beam that I will attach to 4 x 4 posts that I'll set in concrete. 

The deck is 24' wide and the span from the house to the beam is 15.5' I have two major concerns before I get started.

1. Is it possible to span 16' with 2 x 6 for a tin roof? We do not get a lot of snow, but we do get some. How far apart would I need to place the rafters 16" centers or could I get away with more?

2. My other concern is attaching the rafters to the house. After removing the facia board would it be better to attach a ledger board to the end of the exisiting house rafters? Or would it be better to attach the new rafters for the tin roof to the side of the house rafters?

Thanks!


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## Tom Struble (Dec 29, 2008)

http://www.construction-resource.com/forum/showthread.php?t=3166 check the table here


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## TheBug (Feb 2, 2009)

Thanks for the link to the chart. I've checked out these before and from this it looks like a 2 x 6 couldn't go that far. I've had a couple of professional carpenters look at it and say that 2 x 6 would work with a tin roof in our climate.

I would not want to use anything larger than a 2 x 6 for the rafters on such a light roof. 

I'm guessing my only other option is to place a post(s) in the middle of the deck to support another beam in the middle? Not sure that I want to do that.

Any additional advice would be helpful if anyone has any ideas.
Thanks,


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## helifreak (Jun 13, 2009)

*roof*

I was thinking of doing the same. How about using 2 two by six and cut some plywood to put in the middle, glue it all together to make a very strong beam? I am not a expert by no means but I would think that would span your area nicely. I have a 24 foot span to bridge and I was thinking of using 2 by 8 in the same manner to build a beam. I am in the south so snow is not a factor. I just dont want that beam to sag over time. What kind of corner post do u want to use. I would like to use 4 by 4 but 6 by 6 would brobally be better. I have to think about hurricanes not snow!!!


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## Ron6519 (Mar 28, 2007)

Both 2x6's and 2x8's are too small to span that length. They will sag under their own weight.
If you limit yourself to the 2x6's , you'll need to cut the span in half with an intermediate support running the entire length. That span would also need to be supported every 8 ft or so along the way by posts.
Ron


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## Scuba_Dave (Jan 16, 2009)

You want to span 24' with a 2x6 or 2x8?
You can do it, it will sag

That's a large distance to span
What are the dimensions, 24' out from the house? x how wide?
You would need a beam at the 1/2 way point


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## helifreak (Jun 13, 2009)

Mine is about 12 feet out from the house with a 24 foot span across the front. So your opinion is that I can not span 24 feet with 2x8 with plywood sandwiched in the middle and all glued up to make a beam? Is there any way to span that distance? I guess I could put a support in the middle. Should I use 4x4 or 6x6 for the corner posts?


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## Scuba_Dave (Jan 16, 2009)

I'd worry about a 2x12 beam spanning that distance with a roof over it
I'm spanning 12' with 2x12 & using 4x6's as the corner posts


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## Ron6519 (Mar 28, 2007)

helifreak said:


> Mine is about 12 feet out from the house with a 24 foot span across the front. So your opinion is that I can not span 24 feet with 2x8 with plywood sandwiched in the middle and all glued up to make a beam? Is there any way to span that distance? I guess I could put a support in the middle. Should I use 4x4 or 6x6 for the corner posts?


 You can't span that distance with a plywood filler and you can't really use plywood in a weather exposed environment. You will need vertical supports to carry the roof.
The problem with PT posts is that they can check. To eliminate the ascetic issues, I would use 4x4s' and encase them in a poly board.
Ron


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