Reusing Fire Damaged CMU Foundation

[dsargent]

I am an architect designing a new house for a family whose original home was destroyed by fire in december '08. The house was burned down to the CMU, and I am sure that the heat was intense. The exposed foundation wall has been left exposed to the elements since the fire.
A field visit revealed that the cmu are brittle, cracking, and detached from the existing wall.
My client would like to re-use the existing foundation and remove and repair damaged portions of the wall for her new house and garage.
Does anyone have any experience dealing with this type of situation?
I am inclined to tell her that we should demo the entire foundation and start new.

 

[MiketheEngineer]

If its that bad - start new....and used solid concrete. Stronger and more watertight.

I wouldn't even want to chance something like that...

 

[Ron]

dsargent...I agree with Mike...start over.

CMU provides some protection during a fire, but is often more affected by the fire than solid concrete.

For solid concrete sections, check for surface carbonation, as that is the most common affect by fire (in addition to spalling from the sudden water shock of extinguishing)

 

[JAE]

Agree.

Is there a basement under this?

If so, then the fire department's water may also have disturbed or damaged the underlying support soils which, if built upon without reconditioning, might result in some settlements.

I guess even without a basement the water would be an issue.

 

[kslee1000]

Largely agree with all said above. But have different opinion.

I would try to save her some money by take a few samples from the CMUs at grade level. Since the heat of house fire is hotest on roof, and lower at space below. Actually the ground floor might not have experienced much of temperature raises uless fire was directly on it, thus, the subsequent water would have little impact on it, and the foundation wall as well. Take the damaged wall down to grade without damaging rebar dowels, and grout the remaing CMUs solid if test result is positive.

If "SAVE MONEY" is not an issue, then build a new house on a new foundation to save a few bucks on testing should be fine with everyone.