Excavating near a 4' garage foundation

[Dolphin6]

Ok, here are the facts:
1) location - Bettendorf, IA
2) structure - 4 car garage composed of 2-30' sections at 45 degrees from eachother.
3) foundation - 4 feet
4) footing - trench footing 16" wide by 6" deep
5) the problem - The homeowner would like to construct a tiered patio along the outside of the garage foundation. A 15' potion or the patio, to either side of the 45 degree common point would need to be graded 2' below the current grade. This would lower the grade to within 2 feet of the footing. Needless to say there is concern with frost heave. We are looking for comments/solutions for the problem. The garage is insulated with r-19. Thank you for your suggestions.

 

[oldestguy]

Look up on google under the heading insulated slabs. I am doing a job for myself and I need to insulate a slab sitting on the ground and yet do not want soil below to freeze. I am using 3 inches of the pink stuff (closed cell) directly under the slab on the basis of one reference I saw there. Location is Wisconsin.

 

[Dolphin6]

Thanks for the reply. I found a 2004 revised update on building with frost protected shallow foundations. It is quite helpful. Now I just have to check on the local building code. Several sites reference the ASCE 32-01. I beleive obtaining a copy of that (does anyone have access to that article?) along with the local building code will allow me to use the designs outlined in the above referenced NAHB Research article. Check it out. Again, does anyone have access/copy of the ASCE 32-01? Thanks again.

 

[Ron]

Dolphin6...ASCE documents are copyright protected and can't be posted here. That one can be purchased in pdf format.

 

[Dolphin6]

Any suggestion on a site to purchase? Thanks.

 

[JAE]

http://www.asce.org