building code floor question

[Sundowner]

alright, I can get a very good deal on treated 4x6 timbers, and I want to use them for the floor of my small attached garage project. building the garage this way is not only cheaper than using concrete, it's also more unique and in keeping with the Amish barn I grew up with.

problem is, I can't seem to find any codes tha back-up what I want to do. NJ conforms to the UBC, and the closest thing they have for residental garage building codes was written for commercial multi-level parking structures. that code says concrete or non-flammable floors, except for the first floor which may be asphalt. Anyone know of any more applicable codes or references that might help my cause?

 

[MustangRick]

I have never seen or heard of a wood floor in a garage. I would think the moisture from the weather would take its toll on it.
Google "wood garage floor" (with the quotes). There was a picture of a house with a wood garage floor in NJ.

 

[KELLHAMMER]

Nothing wrong about using wood to frame an elevated garage floor. Barns are a good example. IRC Code requires any floor framing closer than 18 inches to grade be "decay resistant" Beams and girders 12 inches or closer to grade as well to be "decay resistant". The IRC suggests cedar, redwood ,black locust and pressure treated for use in these instances. If you have ever seen a bank barn you'll realize it can be done . You'll have to design the floor frame system to be able to carry 100 pounds per square foot minmum. This means the framing will be rather beefy, not 2X stock, except maybe the decking. It helps to use rot resistant material, but it not esentential. I would recommend white oak or doug-fir for all framing. Rough sawn stock can usually be found pretty to be inexpensive from a lumbermill . So you system might look like this 2x decking on 4x6 joists at 16 inches on center. Your 4x6 joist are probably going to be limted to about a 6 to 8 foot foot span with design load of 100 psf. Girders or beams will be sized based on the distance between supports and calculated load.

 

[z28toz06]

I think sundowner wants to use the 4 x 6 timbers as the floor, not the joists,correct? go to a lumber yard and give them the specs of what you want to do. They will tell you according to span, what you can get away with comfortably for joisting vs span. 4x6 timbers are pretty stout and will hold the heaviest vehicle you will want to park on it.

I am not too enthralled myself with the treated stuff indoors as the cca (chromium copper arsenate, chromium=heavy metal, copper=heavy metal and arsenate= arsenic) will always want to leach out, and depending on conditions will try to. Use a mat when laying on it and try to find a good sealer to use on it to keep the dust etc to a minimum. As you walk on it you will track it in to the house and car etc. studies around kids playsets have been known to have over 200 times the maximum accepted level in the soil surface.

 

[kbs2244]

Before you get too deep into this I would run it by the local inspector.
Have him do some of your research.
He is going to be the guy to say yes or no on an attached garage.
I can imagine concerns will wood soaking up spills and leaks of oil and gas.
On a detached building you may be able to get away with calling it a barn or shed, but attached makes it part of the dwelling.