Finishing Basement Walls, Inside Perimeter Drains, and Moisture, Oh My

BSponz1

Hi Everyone - I'm in the early stages of a basement remodel project and would like some advice on how to insulate the masonry wall and install the exterior walls of the finished basement. About a year ago we had an interior perimeter drain installed due to some puddling we had from water seeping through the bottom of the exterior walls. This has stopped the puddling. However, the water still seeps in and enters the perimeter drain. The moisture is not a problem with the basement unfinished, as it is a very rare occurrence and only happens at time of heavy rain or snow thaw. My concern is once those walls are enclosed behind the finished walls, the moisture will not evaporate and will, over time, cause mold growth.

Because of the perimeter drain, the walls will need to be built off of the exterior walls. I've attached a set of preliminary plans (it's great to have an architect for a sister), it's a little hard to see the gap I'm talking about, but if you follow from the sumps at the two corners of the basement you can see what I’m talking about.

Here's what I'm initially thinking of to finish the walls:
· Apply Drylock to exterior walls;
· Install 1.5 or 2 in XPS insulation directly to outside walls (how does this hold up if it comes in contact with water seeping through the walls?);
· Installs Metal Stud Walls, approx 6-10 inches away from outside walls (I don't have the exact measurement on me)
· Install unfaced insulation to metal stud walls (is this even necessary with XPS on exterior walls, and is there concern with this getting wet?)
· Install vents every so often on exterior finished walls to vent any moisture that does get in to interior, where dehumidifier will take care of (if this is done, does insulation on metal stud walls even worth it).

As you can see, I have a lot of questions, so any advice on my plan of attack or any other considerations would be much appreiciated.

Thanks!

Attached Files

10-0201_COMPILEDPage.pdf (73.5 KB, 125 views)

jklingel

Your best bet would be to search on the buildingscience.com site. There are several threads here, too, but the BS site is the source. As always, seal up the outside before you deal w/ the inside.