I-Beam Cantilever Weight Load Capacity ?

[Dan150]

Hello , I'm looking for some help in determining I-Beam Size required for the following- Adding a patio on to the rear of my home and want a clear span at one end.Patio size - 35' long x 13' width x 4" thick concrete slab patio with a concrete block(8x8x16) garage underneath 23' of it , with the door at the end where I want to cantilever the patio the additional 12' so I don't have to deal with the pillar pulling in and out of the garage, and this is attached to the back of the house lengthwise. There would be a beam running from the house over top of the garage door and tying into the beam on top of the concrete block 23' and extending the extra 12' and also running another beam out from the existing corner of the house to meet the end of the other beam at the outside corner of the patio cantilever 13'.(I'm going to remove the top coarse of block from the side foundation of the home and replace it with the added beam. which will make the side beam approx. 26' long with half of it under the house and welded to the center beam in the home and half reaching out to connect with the beam running the length of the patio. There will be a roof over the patio tied into the existing roof which will add more weight. Can anyone give me an idea if an 8" I-Beam of whatever? thickness will handle being cantilevered that distance since 8" would fit nicely ? Or if not I can add support gussets at an angle from the ground with more 8" beams and shorten the cantilever somewhat and still have my clearance I need to get cars in and out. I can build it but I'm no engineer and I would be thankful for all help ! If more info is needed please ask. See Attached Picture !Thank you-Dan150

[RICHARD ZASTROW]

I'm not a structural engineer!!!!! You might want to look up "BeamBoy" on the net.

Dick Z

[Gizmot]

you may want to consult a local architect that knows local building code. This kind of stuff is heavily regulated. Not building in accordance to the local building code may force a city inspector to ask you to tear it down. Or, you can build it so overkill that it will pass any code inspection. But this solution is always more expensive and often unpleasing for the eye.

[Dan150]

I definetly will go through the proper local procedures , I just want to outline my parameters so I know where I stand go into this project. Thanks for your reply

[Gizmot]

what you need to know before anything is the max weight on the structure. That means checking for worst case scenario. Do you plan to have any crazy party with 20 people on there? How much snow can you expect in winter? any special seismic requirement?, etc etc

can you draw a simple top view sketch idea? (including basic size of house, patio etc).

when you mean 8'', is it height or width?

[cam1]

Without going into details, cantilevered beams usually follow a rule that requires a 3 or 4:1 ratio. For every 1 foot of overhang you will have to have 3 to 4 ft of beam inside the structure. A simple example is a cantilevered balcony. For every foot of overhang you will have to have a 3 foot span of beam projecting into the floor. My advise is to consult a structural engineer, as residential structure are designed with a certain floor loading (30-40 lbs/ft^2). As previously stated, you have to follow the local code, or you will lose alot of time and money.

regards

[kballance]

Loads range 10-20lb/sq ft dead load and 50-60 lb/sq ft live load for residences. I use to do residential structural consulting--so look at the building codes for your state, county, etc, Too, most load limitations are based on deflection as well as strength.
Kent