So I've been reading a lot of articles saying NOT to use fiberglass batts in basements as the moisture from the foundation walls will transfer into the batts and cause mold. The overwhelming majority say that fibergalss batts cant touch the foundation walls. However, if I frame my studs a few inches off the foundation walls, then am I safe to use the fiberglass batts within the studs as long as they don't come in contact with the foundation walls? The gap should leave enough room for the moisture to evaporate off the foundation walls, correct?
Thanks for the help.
joecaption and Bud9051 provided good information.
Water does what it wants and the the constraints Bud9051 notes apply not only to the insulation, but all surfaces in a basement. Basements are heat sinks.
That said, we hung twelve foot wide 6 mil plastic in a continuous sheet on the basement walls by wrapping furring strips a few times and screwing them to the top of the wall with concrete fasteners. The remaining width draped to and over the floor. We then framed on 24" centers (non-bearing) on the plastic (pressure treated studs for bottom sill plate), ran our electrical and insulated with paper faced four inch R13 thick batts. We than ran more 6 mil on the concrete floor and seamed with 3M™ Polyethylene Tape 483. On the floor we used a felt under layment and floating floor. This provided some insulation and give. Solid concrete will eventually do your leg joints a disservice. All walls, ceilings and sofits covered with standard drywall. No issues since install three years ago.
We used two 100 ft rolls of 6 mil at about $70 each. The tape was about fifteen bucks. The 6 mil is more robust than 4 and IMHO easier to work.
This configuration not only limits the moisture penetration from the surrounding earth, but also inhibits the effects described by Bud9051. We went one more and installed a 70 qt. dehumidifier on a shelf with drain to safe waste. This makes for one less thing to do and keeps the humidity down in summer months. We notice a marked difference between a 50% relative humidity setting and 60%.
I configured for a mini-split ac unit, but since in the dead of summer, the basement never gets above 78, I doubt it will ever be installed. For heat I ran fin tube off our 75 gallon water heater with a domestic water rated circulator and across the line digital thermostat. In spite of many naysayers, the basement is the coziest place in the house.
Water flows downhill and basements are the lowest level. You will want to manage sources like water heaters, drains, humidifiers, sumps, pipe penetrations and similar to avoid collateral damage. We have battery powered moisture alarms purchased in a three pack that helped during a long rainy week where many had flooding.
Hope this helps and good luck.
We have a similar area as you show in your picture. I left as is. Since the near all the walls and floor is covered, that little bit is easily captured by the dehumidifier.
