what to do with older crumbling foundation

Old 01-13-06, 02:11 PM
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what to do with older crumbling foundation

I have an older (1912) concrete foundation that is crumbling. I have been told by several people, including an engineer that it is structurally sound for the time being, but as the crumbling is an ongoing process, I expect that in the future it will become problematic. I know that one option is to have the house raised and a new foundation poured, but I also know that this is expensive and will ruin some of the interior (drywall and plaster repairs) which I have already done at considerable cost in time and money. In addition the house is three story and very close to neighboring houses so lifting would be complicated. Another option which has been suggested is to build wooden 2X6 walls from pressure treated wood, faced with pressure treated plywood and plastic against the inside of the old concrete and fastened at the top and bottom. This had already been done on one wall when we moved in and seems to have worked. THere is no sinking or water infiltration on that side of the house. This provides some support for the house as it is tight against the first floor joists. However, I know the sill plate is still sitting on the concrete and not directly supported by this new wall. A third option I have considered is to pour new concrete inside and outside of the existing wall, with better waterproofing on the outside to prevent the water infiltration which contributed to the current concrete breaking down. If I do this, how thick would the concrete need to be inside and out? WOuld the remains of the existing concrete in the centre of this sandwich provide sufficient support for the sill plate or would I need to bridge the gap between the new walls somehow to support the sill plate? Any thoguhts on this or my other options?

Old 01-16-06, 02:18 PM
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Mine too, is a so called crumbling foundation from the mouth of the home insurance man , I suspect his knowledge is limited. The foundation consists of large brownstones with a mud? gout resulting in a 18" thick wall and is about 80 to 100 years old. The PO (previous owner) reinforced it with concrete block in several places resulting in a small "trash room" and a nice walk in bone dry basement.
I think, providing I keep it dry and repaired, it will last forever... Pretty it will never look.
Old 01-16-06, 03:17 PM
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what to do with older crumbling foundation

Bruce -

It appears you ahve a sound foundation with a surface deterioration, since the engineer gave it a structural O.K.

Your proposed ideas may seem like overkill but probably are not practical from a construction or structural point of view. They would require major changes in the way the loads from the house are distributed to the ground (framing, sills, new footings).

It sounds like you are trying to fix it now, rather that wait. The wait could be very long since the loads on a home foundation are very low. You did not mention the thickness, but I suspect it may be subastantial. The fact that your house is 3 stories may actually be a benefit.

You would be best to act to preserve the appearance and integrity of the existing foundation.

I would suggest sticking with concrete or masonry for any future work. Your patch job with 2x6s may be working O.K. (if it really carrying a house load AND the lateral soil loads. The high shrinkage of the wood may reduce the support supplied. The history of wood foundation is not good and they are now really just history for any serious construction.

Try to preserve what you have since it is only 90 years old and hire an engineer in 20 years to look at it again.


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