Compounding cantilevers - how to cantilevered 3rd floor on a 2nd floor that is cantilevered over 1st

[bnymbill]

I'd like to know what the options are for building a 3 story row house with the 2nd and 3rd floor cantilevered. There are two ways to do this:

1. If the 2nd floor is cantilevered 3' past the 1st floor, can the 3rd floor be cantilevered 3' past the 2nd floor? Both are assuming joists extend at least 9' back into the structure.

2. If no. 1 is not feasible; how about if the 2nd floor is cantilevered 3' past the 1st floor, can the 3rd floor be built on the same footprint as the 2nd floor?

Does the weight and leverage of an additional story of house reduce the distance of cantilever the 2nd story can extend?

Thank you,

John

 

[JAE]

Yes, you can cantilever as you describe for both options. You need to design the cantilever members (beams, etc.) to support the required loads.

The distance that you can cantilever depends on the beams that are doing the cantilevering (is that a word?).

You indicate you are a structural engineer. What don't you understand about this sort of design?

 

[bnymbill]

Hey JAE,

Thanks for getting back to me so quickly; I'm not a structural engineer - that was actually a mistake in setting up my profile, which I'll change ASAP. I'll need stamped plans eventually but I wanted to know what my options are for a floor plan. City houses are small which limits layouts and I'd like to use the double cantilever on two that I'll be rehabbing in the near future.

Thanks again,

John

 

[msquared48]

And, John, your profession is.... ?

Mike McCann
MMC Engineering

 

[sbouvia]

Developer? Looking for Schematic Design apparently.

 

[ztengguy]

with money and resources, anything can be accomplished. Hire a architect to look at it, then a engineer to put him in his place.