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tjames64 04-30-2011 10:15 AM

2x6 attic floor joists
Hello all,

I'm new to these forums so I'd first like to say hello to everyone. I have a few questions for you all. I own a small cape cod 1.5 story home. The home is 25'x 26'. The upstairs floor joists are only 2x6s. There already is 2 bedrooms upstairs being supported by those joists. My first question is, would I be able to expand the upstairs roof and make it a full 2nd story with a full bath room? My neighbors friend is a contractor and last year he said he'd build all new walls and put on trusses for $20,000. I just don't know if they will support all the weight of a bathroom and such. Also, I want to remove a 1st floor wall. Even if the joists run the length of the home and dont rest on the wall, do I need it still for support? The wall runs perpendicular to the attic floor joists so I thought it would be a load wall, but the wall only runs half the length of the home. If I removed this wall and the joists run the 25' of the home, would it be safe enough to walk around up there? Sorry for the length of the post.

DannyT 04-30-2011 11:25 AM

i've never seen joists 25 foot long. where i used to live a 2x6 could span 12 feet for a ceiling but for floors most were 2x8 or 2x10.

tjames64 04-30-2011 11:59 AM

Thanks for the reply. The attic floor joists are definitely 2x6, and the 1st floor wall only runs half the distance of the home so some joists are longer than 12' for sure.

Daniel Holzman 04-30-2011 12:45 PM

I think it is unlikely (not impossible) that you have 2x6 joists supporting floor load and spanning 25 feet. If they do, you are way out of spec for any code used anywhere in the U.S. I am not sure I understood what you were saying about your contractor quote to replace the joists and add trusses. Are you talking about using 25 foot long floor trusses to support the bedrooms/kitchen on the second floor? This may be feasible if you have the appropriate vertical clearance.

In any case, you need to prepare an accurate, scaled drawing of your existing framing. Then you can start planning. I have looked at lots of houses over the years, I can't remember seeing a 25 foot span 2x6, but if you have it, you are certainly going to need to replace such a joist with a much stronger member. The exact size will depend on your location, the floor load code requirements, and the type of joist you are planning to use.

As for removing the wall, that is going to require a header, which must be designed for the loads. Headers may be designed by an engineer or architect, or they can be sized based on tables, or sometimes the lumberyard supplying the header beam will size it for you based on the geometry of your house and the floor loading. In any case, it all starts with an accurate, scaled framing plan of existing conditions.

jcrack_corn 04-30-2011 10:23 PM

25ft span 2x6's absolutely exist.

often used for high roofs, for the rafters..

only problem is they are finger jointed and needs to be used with knee walls/support struts.

lol about them otherwise.

tjames64 04-30-2011 10:28 PM

So heres another question. If I hire a contractor to make my upstairs a full story, should I use a floor truss system, or go with I joists? Which is better, and are floor trusses even used for a 2nd story floor?

Tizzer 05-01-2011 02:08 PM

Just so we're on the same page here, you are wanting to make this 1 1/2 story cape cod into a full 2 story home?

Yes, I joists are used for any level floor systems.

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