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Insulating foundation stemwall on bedrock. Climate zone 4c

DaveHope | Posted in Energy Efficiency and Durability on

I am trying to figure out a configuration for insulating a perimeter foundation stem wall that is going to be on a combination of glaciated bedrock, and 6< fill.

This is for a small timber frame cabin, that is 24 square.  The sides will be resting on the bedrock, with the middle of the structure is on the infill.

I am trying to avoid foam products if possible, and am planning on using mineral wool for all insulation including under slab and exterior foundation,

At this stage, my ideas for the foundation are to use Fastfoot membrane under the footing(where a footing is needed) and under the wall over bedrock.  Then seal the fastfoot to the foundation and the remaining foundation with a waterproof flexible membrane both inside and outside.  On the inside, under slab, 6mil poly over the Rockwool comfortbatt, and seal the poly to the waterproof membrane.  On the exterior, cover the water proof membrane with a dimpled drainage layer, then Comfortbatt outside this.

The interior floor will be polished concrete.

Natural stone will be used as cladding from the bedrock or footing level, up to a point two feet above the internal floor level.

The recomendations I have seen regarding air gap for natural stone is 2 inches. Does this seem like an excessive amount of air gap?  I will be putting 1 inch pvc drains through the stonework every 18 inches.

Any feedback and punching holes in ideas is welcomed

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