Adding loft to 560 sq ft home

[lxlspeedr]

I am a younger carpenter thats been tossing up the idea of adding a loft to my home, but looking for more imput on my situation. The cabin 29x25(roughly) was built in the 70's and was converted into a home before i purchased the property.  I am location in WNY where the winters can get pretty rough.  My footer is only 6"x14", the foundation is only 4 courses of 8" cmu tall.  There is one course of block above the ground so that puts the bottom of my footer right at frost line. I have contacted a local engineer concerning my foundation, he told me I am godfathered into building code, min. size for footer to support a second story is 6"x12". Also told him I installed Quikwall on both inside and outside of my foundation to reinforce the walls. The engineer gave me stamped letter to give to my building inspector saying I can add a second story. I would like other opinions on if I should go up on my foundation or not.  I have a couple older co workers telling me not to but still not sure what to do.   What do you guys think? Thanks for your input.

[Don_P]

At 25' wide I assume there is a center girder under it? If so it is supporting half the floor load and depending on the framing it may be supporting half the roof load. At 12" wide in "typical" 2,000 psf soil the footing has an allowable load of 1 ton per lineal foot. You have roughly 60 feet of footing on the load bearing sides, so 60 tons of capacity. Quick and dirty.. house is about 600 sf, roof the same, 2nd floor the same, 1800 sf. Divide 60 tons... 120,000lbs (assumed soil bearing capacity under the footings) by 1800 sf = 66 psf... floors are usually 50 psf combined live+dead load, roof is 10psf+ snow load...unless you have a hundred pound snow load or bad soil under you you're good.

[lxlspeedr]

Yes, there is a center steel beam. If it was built right the load bearing wall would be over the beam but it actually runs perpendicular to the beam. Another thing I forgot, this past winter one corner of the footer heaved , maybe 3/8", in a 2' span.