floor joists in attic

Old 10-09-03, 12:50 AM
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floor joists in attic

I have a cape cod style house. The attic is unfinished. To save money, I guess the builder used 2x6's for ceiling joists. I know this is not going to be strong enough to use at the floor joists when I add 2 bedrooms and a bath upstairs where the attic now is. How should I strengthen up the joists? Could I just put another 2x6 between the existing ones, which would make them 8 inches on center instead of 16. Or do I have to do something like nail a new 2x8 to the existing 2x6's? Any help is greatly appreciated. Ken
Old 10-09-03, 09:12 AM
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I am thinking you will install a dormer (or two...) to make this all happen. The dormer work is serious renovation, and most likely you will have contractors doing the work for you.

If the contractor has experience with dormers, they most likely have experience and opinions on dealing with the joists.

No two houses are the same, so expect a parade of contractors scoping out the house before they make any proposals.
Old 10-13-03, 07:57 PM
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not enough info

A lot more information is needed to give anything close to an accurate answer. As well, it is best in these circumstances to have a professional engineer design a floor system for you b/c no one on the internet can see other structural factors that may be impacted by the work you propose. Typically speaking though, adding more joists of the same size to 8" o.c. or doubling up the single joists does not usually work. We have in the past added larger joists to frame a new floor, but it all depends upon the structural loads coming from above, the load bearing points that are available below (i.e. first floor walls) and what the span is for the joists.
Old 10-14-03, 03:13 AM
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The builder did not put in 2x6's to save money, that was the code. It still is. The size of the floor joists has to do with the live load over a certain distance. You are trying to do something with your attic that it was not designed to do. As mentioned we cannot really help you much even though we are professionals due to lack of information. You flooring system and bearing wall system will need to be looked at by an engineer. I have seen these attic floors give way, and the toilet is suddenly sitting in the living room. Bad deal. Good Luck

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