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Small Cabin Forum / Cabin Construction / Rough cut instead of engineered lumber
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BY5260
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# Posted: 8 Jun 2013 08:01pm
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I'm new here so excuse me if I missed this subject already being addressed. I have a cabin under construction in the mountains of Utah. The shell is completed and I'm getting ready to start the covered porches on (3) sides of the cabin. I have engineered plans showing the footing requirements and the building requirements. I'd now like to change the way it is built. The original plans show 2x12, 16" o.c. rafter with (3) 1 3/4"x 11 1/4" LVL header on 5 1/4"x5 1/4" PSL column, 12' o.c. There are other engineered items shown in the plan and I'd now prefer to use rough cut pine that I can stain and leave the structural aspect exposed from the bottom with a nice look. My question is; Is there a chart or some reference I can use that would show "what" rough cut lumber would be the equivilant of say the (3) LVL's I mentioned above? I actually plane to reduce the spans that are shown on the original plan so I'm confident the B.I. will be okay if I can show some info that shows I'm still using adequate material for these porches. For example; the original plans and design are for a 12' deep porch. I'm reducing it to 8' in some sections. Also, the 12' span for columns will be reduced slightly depending on window placement in the cabin. Any suggestions?

ICC
Member
# Posted: 8 Jun 2013 10:05pm - Edited by: ICC
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Quoting: BY5260
My question is; Is there a chart or some reference I can use that would show "what" rough cut lumber would be the equivilant of say the (3) LVL's I mentioned above?


simple answer is No. There is no table or crossover list for timbers to LVL like there is for different spark plug brands. You could try working backwards from the spec'd LVL using the span tables for the mfg products to see what sort it can handle with the column spacing presented on the plans. Note there are many grades of LVL's just as there are different lumber grades, different E values.. Then you'd have to calculate the timber size needed for the loads and the new spacing. You need to know the species and grade of the timber as well. It's not quite the same or as easy as looking up rafter or floor joist spans.

what you should do first though, IMO, before taking time and effort to try that, is to talk to the inspector you are trying to impress and win over. Many will not give an okay to ungraded lumber or timber, and that is what it sounds like you will have. Some will want an engineers to stamp the design. Some locations recognize there are people who want to use ungraded timber / lumber and have special provisions in there code or rules. Other places do not. Ask the inspector what sort of info he needs, what sort of rules they apply.

It's also unclear to me from your word picture where those LVL's are and what they will be supporting. And are they used end to end or in a sandwich of all three side by side? Beam sizes can be calculated if one knows how. But to do so we need more info; species of timber (we'd assume #2 grade), the loads in PSF (incl snow loads, special wind or earthquake zones....) , spacing of columns, also height of columns to check them. But even if we have all that it will not count for anything IF the inspector goes by the book as the book says you can do things that are not listed but you need an engineer to say it's good.

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