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building a gambrel roof on a post/beam base #5043 04/02/02 08:45 PM
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gernan Offline OP
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I have read several books that refer to building a gambrel roof on top of a post frame base of a barn.
(a common repair the books states).
The only designs/pictures I see show a 2x? laminated frame extending into the roof structure.
(Louden barn plans)
I have a 30/48 structure with 8x8 posts (12'oc.)
All these posts are embedded in concrete 4'
into the ground.
The ends wall have 4 posts with the middle
2 posts made of laminated 2x8 which are bolted.
These can be rebuilt to extend to the roof line.
I am looking for books or plans
that show the different methods of building
a gambrel roof.
I would like to use a Iowa or Shawver(sp) like
truss or something like it to keep the middle
of the barn open.
It will have a metal(Pro panel type roof covering)
The snow load is 50 lbs so some of the designs
I have seen look to weak to be used.
Any info, ideas, or direction would be helpful.
Also,if this is a bad idea, then let me know.
Thanks Gerry

Re: building a gambrel roof on a post/beam base #5044 04/06/02 09:13 PM
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Roger Nair Offline
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Agricultral extension services and USDA may be able to provide some guidance, such as plan 5626 at http://www.ag.ndsu.nodak.edu/abeng/plans/Construction1.htm

I have seen such construction in WV but I have great reservations about using that pattern. The extension service pattern solutions were developed in the depression to serve necessity and may not pass modern code.

If it was my task to provide a TF solution, I would start my investigation with a principal purlin and queen post truss structure with common rafters, a very much more expensive solution than you seem to require.

If the lumber truss route suits you, contact a truss fabricator or a lumber company, that serves pro builders, will set you up with a fabricator. The fabricator will have design and testing resources that will solve your concerns.

I would also suggest you get an engineer for design overview and to forecast the life span of a concrete embedded post foundation before making improvements.

Re: building a gambrel roof on a post/beam base #5045 04/06/02 10:47 PM
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Jim Rogers Online Confused
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I agree with Roger, to check out your posts in concrete.
It's been my understanding that if you put a post into a hole and then fill it with concrete to hold the post, you are creating a cup with the post in the middle. If the bottom of this giant concrete cup has a hole in it for the water, (whatever water may get into it, from anywhere) to run out then you might be ok. But if the concrete cut doesn't have a hole in it, then the post is sitting in water. Water rots wood. There is (I've been told) no such thing as dry rot. Water, if it gets in this cup, will rot your posts.
Now if this building has been standing for years and there is not apparent damage you maybe ok. But who knows. You could have a problem you don't know about and adding weight to the structure could cause problems.
Good luck with your project,
Jim


Whatever you do, have fun doing it!
Re: building a gambrel roof on a post/beam base #5046 04/28/02 07:38 PM
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Wolf Opel Offline
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There is a truss that would deflect the load into your outside walls, and it is called a 'barn truss'
Basic principal is to deflect the load from a ridge beam through a king post into the outside walls. Span seems to be all right for that.
But unfortunatly there is not enough information to say if it would work.

And definetly have an engeneer check out your foundation. I coudn't agree more that you may run into big problems if you don't.


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