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axiom10 04-11-2010 09:09 PM

New Foundation: Minimum height of concrete above openings
Hi there,

I am pouring a new concrete foundation for my existing house. The foundation walls will be 8' high and 8" thick of 3000psi reinforced concrete. The house has a large 8"x8" beam running along the entire perimeter of the house that will sit on top of the new foundation walls.

I would like to have several openings for 2' x 2' windows in the foundation walls. I would like to place the windows below the top of the wall leaving a span of concrete between the top of the windows and the top of the wall. My question is, what is the minimum height that this span of concrete should be? Obviously there will run rebar across the span, but I am still worried about cracking if I don't go thick enough. I am currently working with 6" of concrete above the windows in my plans.

I would appreciate any thoughts.


jlhaslip 04-11-2010 10:02 PM

Is there a rim joist above the windows?
Turn the rim joist into a header sized piece of material and you can place the windows as high as you want to.
Is there an Engineer involved? Ask them.
Or a Building Inspector in your area?

(where are you?)

axiom10 04-11-2010 10:26 PM

The floor joists are attached by hangers to the 8"x8" perimeter beam, so the beam acts as the rim joist. There would be very little load (none?) on the concrete above the windows.

An engineer would be nice but not in the budget. I am on PEI in Canada.

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