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spanning i-joists for warm roof
Hi guys,
To introduce myself I have been in business for 10 years doing bathroom and kitchen remodeling. On this particular project in question I am adding an addition on my own house and would like some feedback on the joist sizing.
I am doing a low pitch 1/12 , rubber roof. In order to maximize the height in the room I need to use 2 by 10 joists maximum. (2by 12's i lose 2 extra important inches). The clear span of the joists is 13 feet, 10". I will be spraying foam under the roof deck sheathing. I need to space my joists 24"O.C. (It is too involved to explain why 16" OC will not work).
From the load span tables (Number 1 southern pine, 2 by 10, l/360 deflection, 40 psf live load, 24"oc I know that the maximum allowable span is 14'7". Again my span is 13'10".
My question is.... Is this too close to maximum span? I live in southern ohio and we do not get tons of snow, 23" per year maybe. I tend to error a little on the conservative side as a general rule (slightly overbuilding).
One thought is that every third joist I would double up and bolt them together.
I do not want sagging problems over time (30 years, and beyond).
However, maybe I am being a bit too cautious or over-concerned. Will you advise just to do the 24 oc spacing (not doubling up on every third or every other... and be done with it?
Additionally, I was planning on 5/8 osb (remember 24"oc) - will this be strong enough? Go to 5/8 ply? 3/4 osb? 3/4 ply. Again, I want long term durability, but not to OVERSPEND(wasting money where it is not necessary). Thanks...
Scott
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