Regarding cellars, retrofits, and capillary breaks
The house is in the process of being purchased and will undergo a complete gut rehab and deep retrofit. It was built around 1910 located in upstate NY in climate zone 5A. The basement has a dirtfloor and a height of 6′ from the dirt to the bottom of the 1st floor, floor joist. There was an addition put on that has a crawl space attached to this area. There was another addition that was was partially dug out- it slopes rather steeply from grade to 6′. This part is also attached and happens to have a well or a cistern in it. It’s 15 feet or so to the water level. I am thinking it is a well, but will have to confirm. The foundation is brick and extends approximately 1 foot above grade. The only sign of moisture issues I found was mold on the an object on the floor near the well. From what I remember (I was last in the basement a few months ago) the bricks showed minimal signs of damage or discoloration, although there had been a few repairs.
I would like to treat this area as a cellar and completely isolate it from the house with access through (existing) Bilco doors. I would like to add 2-4″ of rigid and fill the joist cavities with cellulose. However, it seems the overwhelming majority would say treat it as semiconditioned space and insulate and seal the foundation walls and floor.
The cavities between the floor joist, over the foundation, and against the rim joist will require further thought. In the deep retrofit I may only be able to use 2″ of polyiso which will be installed on the exterior of the rim joist. The capillary break between the foundation and wood is another issue. I am unsure that I will be able to jack up the house to install a membrane of some sort.
So my questions:
If liquid water is properly addressed, i.e good exterior and interior drainage practices. Is it possible to get away with just insulating and air sealing the floor? If so is closed cell spray foam more or less the best way of addressing the cavities along the rim joist? Are there other acceptable alternatives?
Again assuming proper water management, am I asking for serious trouble if a capillary break is not installed between between the foundation and wood?
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