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Old 02-02-2012, 11:52 PM   #1
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Gambral shed input please

Ok so The guy I'm staying with has a concrete pad on the property. Well we had a Ef3 tornado come through here and it took the shed with it. So now we have this 17'6" X 11'10" concrete slab to work off of.

So the guy has given me a couple of requirements that must be met.
1, Standard 8' walls and ceilings
2, Gambrel Style roof
3, Basically built to code in Virgina
4, It must cover the entire existing slab

2011 we had a snow storm yielding more than a foot of snow, a tornado, an earthquake, and a hurricane so the structure needs to be quite sound.

Ok simple enough however this is the largest project i have ever taken on. I've built well houses and wood sheds along with various repair work over the years. I am confident in my ability to get this done and to have rent waived for a few months .

Like previously mentioned I've never done something like this before. So before i can start i need to make a materials list (which is mostly complete). My method in doing this was to build the shed one board at a time using Google sketch up which is free 3d modeling software. Well before last week i had no modeling experience but i developed the basic skills to do what i needed.

Here is what i have done so far at various steps

Walls 8'

Gambrel trusses there will be a total of 17 of these, plywood will be used to tie these together at the joints.

The outside, a few details yet to be done

that overhang comes down so that i won't need to run a thin strip of T111 across either top or bottom of the wall. a 2X8 will fill the gap between the roof and wall. the corner will need to be ripped down to the appropriate angle to match the pitch of the roof.

Another interior shot of the interior

As you can tell I'm no construction worker nor am i very good at 3d modeling. I'm not going to stray to far from this design but i would like to know if the roof structure is going to be solid enough to withstand a foot or so of snow and hurricane force winds. I'm not really banking on another tornado or earthquake in the foreseeable future.

Thanks for looking!


Last edited by Tony85; 02-02-2012 at 11:58 PM.
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Old 02-03-2012, 01:03 AM   #2
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Whether the shed lasts for a 100 years or not is going to depend on all the small details you haven't mentioned:

How you bolt the wall plates down to the concrete pad.
What sheathing you use, and how many nails you use to nail it down.
Whether you hold the rafters to the walls with hurricane clips.
How much plywood you use to hold the truss pieces in one piece.


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Old 02-03-2012, 07:08 AM   #3
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I'de move with all that weather.
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Old 02-03-2012, 08:16 AM   #4
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I would add a collar tie at the ridge as well a continuous ribbon on top of the collar tie and the ceiling members (perpendicular to the ceiling members). You might also consider incorporating some diagonal bracing on the vertical members too. The 2x8 "soffit member seems excessive. Gang nail plates are an alternative to the plywood gussets. Ditto to the previous comments because all will be for not if its not tied down correctly.

Last edited by Marvel; 02-03-2012 at 08:20 AM.
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Old 02-03-2012, 11:02 AM   #5
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The shape you included in your initial post is NOT a gambrel truss. A truss by definition is a structure composed of triangles. You are missing three pieces that would make the structure a truss. You can see what an actual gambrel roof truss looks like on

The advantage of a truss is that all of the elements are either in tension or compression, with no bending moment. The actual sizing of the elements depends on the loads on the truss. Since most DIY'ers lack the skills and software to compute forces in a truss, it is common to rely on a proven, engineered design which has already been analyzed and approved for use in your area. A lumber yard would have premanufactured trusses available in specific sizes, and you may be able to order trusses in non-standard sizes. It may not cost any more to purchase pre-manufactured trusses versus trying to build your own, you need to see what prices are in your area.

If you do in fact want to build what you showed, that is a traditional roof design with rafters and a pair of vertical supports. You need to decide if you are going to use a ridge board or a ridge beam. If these terms do not mean anything to you, I suggest you purchase a book covering standard framing techniques. Such a book will offer you information on laying out the roof framing, connections, sizing the elements, and installation procedures. Worth the money for sure.
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Old 02-06-2012, 08:36 AM   #6
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As usual another well considered and useful response from Daniel.


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