am building a garage above wich will be a living room and a patio
span on trusses supporting hte garage roof and 2nd floor will be 24 feet
considering using laminated (stacked) 2x4's how many will I need to safely support the load and not have any sag in center ??
JOHN
Insufficient information for a meaningful answer.
RJOHN:
Stacked unattached [2x4]s will deflect together exactly as one single member.
Each one is responding to the load separately. If a 1lb load results in
1" deflection, in a stacked array 10 [2x4]s under a 10lb load will also deflect 1" total.If, however, you have bonded the wood members together with a suitable adhesive the strength of the greater beam is many times the strength of each one or even the ten separate members together.
If you had a lot of available [2x4]s you could make quite efficient beams and joists. The strength would be close to that of composite wood beams of the same sizes and material, although TJIs would weigh less and be more uniformly straight.
How to laminate them is a question: the type of wood, type of adhesive and the clamping means with clamps or nails.
Call a local civil engineer or architect to get a calculation based upon the loads that you plan, length and depth of beams. Or, contact a maker of laminated beams to get some numbers on sizes for your application, loads, and the type of wood they use. Check their prices to see if you are saving money.
Ralph Hertle
JA_MORAN wrote:
Ask your local building department for the codes that govern the building. With a residence above the garage you may have to put in a 1 or 2 hr rated gypsum wall board ceiling and walls in the garage. 1 hr is the norm for the residential areas. Figure 5/8" thick GWB for a 1 hr rated wall or ceiling assembly, taped, and with no gaps, and 2 layers of
5/8" GWB for 2 hrs.Ralph Hertle
Don is correct. You can use TJI's "Truss Joists I shaped" from your local distributor. This will support the floor living room floor and patio. Then you should use roof trusses by a local manufacturer to be the roof framing. Loads are dependant to where you live. Common loading is 40 psf for your living room floor and roof needs to be designed for snow load ( depends on where you are ) and also wind/seismic load again dependant where you live. But, before that you need to at least get a local home designer or architect to do the small architectural project so you can get a building permit from your local area so you can be building this within the law. Good luck.
CID...
Correct no need to check what you are telling him is completely correct. Not to mention lateral load at the garage doors to provide seismic/wind holdowns at the edges of framing. He has mentioned nothing about what the walls are going to be either.
{ I don't think he is getting an answer that he expected.}
CID...
Isn't this sort of thing covered in the FAQ?
The OP mentioned that there'd also be a patio off of that second floor living room, so this is a party room and the deck loading might have to be 60 PSF instead of 40 PSF or the snow load. Let someone else design it. If you're intent on using stacked 2xs (don't), you should check the price of wood first - your way could easily cost double the price of TJ's and that's not including your labor.
R
Depending where he lives and if there is a building permit involved, no mater what, he will surely require submittal drawings and a structural engineer to do the design of the structure and foundation. This will be requested by the building department. If he lives in a seismic area this is usually required no question. By now he more than likely has decided not to do this project.
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