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jamesinkster
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# Posted: 25 Jun 2012 01:09pm
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Hi,
I'm working on my tiny shack... it's 8'x12'.
I've built the floor platform, and am just about finished framing my walls. They will be raised and hopefully sheathed next weekend.
The walls and floor were built 16" OC. The floor is made up of 2x8s.
Which leaves the roof...
It is a simple slope shed roof, sloping from front (11') to back (13'), which is what -- about 14 degrees?
I'll be covering it with metal roofing (on top of OSB or ply), so it'll shed water no problem. This is on the west coast of Vancouver Island, so we'll get tons of rain, but very little (if any) snow.
Two q's:
1. Does my roof need to be 16" OC? I was thinking I could save a wee bit of money and build it 24" OC, but I don't want to do that at structural expense.
2. How thick does my roof need to be? Can it be built with 2x4s? Or do I need 2x6 or 2x8 or ?? It will span the 8x12 with about 16" overhang on all sides...
Any help appreciated!
thanks,
james.
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Sustainusfarm
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# Posted: 25 Jun 2012 01:52pm
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Quoting: jamesinkster 1. Does my roof need to be 16" OC? I was thinking I could save a wee bit of money and build it 24" OC, but I don't want to do that at structural expense.
Your only going to save the cost of 1 or 2 pieces of wood...I would just do it right....
Are the roof rafters spanning 8' or 12'?
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jamesinkster
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# Posted: 25 Jun 2012 02:33pm
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Good question... they will span the 8' (well, 8' + 16"x2).
Thanks!
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Sustainusfarm
Member
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# Posted: 25 Jun 2012 02:49pm
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2x6 should be fine 16" OC...with no snow load a 2x6 can go upto 11.2ft of span. I got this from a span calculator here...
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Retired
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# Posted: 29 Jun 2012 05:27pm
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I don't know if you used 2x4s on the walls or 2x6. If you plan on insulating the roof, you would want to use 2x8" material for the trusses with walls 6" thick, 2x4 construction on the walls 2x6 trusses, as you will have to have 2" of air space to vent to the roof at the peak (Using plastic roof vent across the peak and down at the eaves. This way the air flow from the eaves, running under the roof sheathing to the vented roof peak will allow air circulation between the insualation, and the plywood roof sheathing.
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MtnDon
Member
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# Posted: 29 Jun 2012 06:26pm
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Ditto the question on roof/ceiling insulation. Give that some good thought now, rather than later.
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OwenChristensen
Member
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# Posted: 29 Jun 2012 08:14pm
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That insulation point is huge. Even if you don't want insulation, you might someday. As far as spacing, that depends on sheathing. Since snow load isn't a problem, the issue then might be to limit warpage of the sheathing. Closer spacing will help.
Owen
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flyrdr
Member
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# Posted: 29 Jun 2012 09:53pm
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I think the idea is to have each rafter supported directly underneath by a stud but if there isn't much snow load it might not matter all that much
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MtnDon
Member
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# Posted: 29 Jun 2012 10:33pm
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If the bearing wall has doubled top plates then it doesn't matter much if the rafters don't line up exactly with the studs.
As long as the sheathing used to sheath the roof is rated for the span used that's all that is needed. Of course on a small roof 16 or 24 inch OC makes very little difference to cost; I'd go 16" OC myself.
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