Mr_brighttt OP t1_ja6ld3i wrote on February 27, 2023 at 5:35 AM

Reply to comment by ajtrns in Waterproofing and insulating interior basement by Mr_brighttt

So should I only seal the rim joists and accept it as enough to help with air leakage and call it enough? I bought the house from family and there’s never been any bulk water issues for >10 years. As far as vapor goes, is there anything I can do to allow the concrete block walls to still dry to the interior? Mineral wool bats mechanically fastened to the walls? Since air penetration through the walls is minimal.

I can’t envision any significant open air gap behind the rigid insulation allowing the insulation to be effective thermally

ajtrns t1_ja6m9ym wrote on February 27, 2023 at 5:45 AM

there's no easy way to retrofit a vapor barrier between the top of a concrete wall and wood sills / rim joists.

i can't say how the mineral wool would perform. it would likely become a mold substrate, and whatever interior wall finish surface is covering the mineral wool, the foundation side of that would see the condensation.

i couldnt give any more useful guidance on this. as a handyman and carpenter i'm often asked to retrofit spaces. i have torn out more than 10 basement interior insulation assemblies, perhaps average age of 20-30 years old. until active ventilation products mature, or new insulation technologies are invented, there's just no way i could guarantee my work under such conditions. i only water/vaporproof and insulate from the exterior. i'm wrapping the exterior of a house and its slab in 2" of foam this week.

to be clear, mold and moisture get trapped either way -- interior air or exterior ground contact. the difference is that the exterior assembly does not foul interior air quality, and can exist for decades in a moldy wet subsurface environment and perform its job well. not so for interior assemblies.

Mr_brighttt OP t1_ja6mmyk wrote on February 27, 2023 at 5:49 AM

I look forward to building a home some day with perfected water management and continuous insulation exteriorly too. Cheers