Temporarily exposing a footing to frost during excavation...

[KevinChez]

The townhouse under construction has a party wall. The neighbor extended their building - new foundation wall inboard of property line. Now we are matching and building an extension For us to build new extension our foundation wall will match base of their wall. During excavations and construction of our new wall we will be temporarily exposing their wall to frost (this is in New York City frost depth is 4' below grade).

The code says I need to protect the adjacent property. I do not see an issue with the footing being exposed for a few weeks. But if there is a stretch of below freezing days I am not sure of the potential damage?

 

[MotorCity]

If I was in your shoes, I would at least make an attempt to prevent frost heave. I would think that a few weeks of cold weather would be more than enough time for frost heave to occur if the conditions were right.

A few suggestions......keep the excavation clear of water, snow, and ice. cover the exposed area with insulation and blankets before leaving for the day. build a small heated enclosure.

Oh, and don't forget about not undermining the existing foundation. If you do, you won't have to worry about frost anymore.

 

[oldestguy]

Concrete is a good conductor of heat. There even may be a code requirement about exposing to cold. Once frozen, it seems soil does not want to get warmed up too well.

 

[cvg]

I would say there definitely is an issue with it being exposed for a few weeks.

I would make more than just an attempt to protect the adjacent foundation, I would go the extra mile and document everything. if the adjacent building ever has any foundation problems, even if it was not caused by your project, guess who will get blamed?