During a short bored spell while working on basement a while back (month and half at least) I decided to start a small "building science" project to test the old method of framing and insulating. That method of course being argued between old school contractors and and newer so called "learned" folks (I.E. My construction friend and I)
He felt I was wasting time and money doing the rigid foam all around and then framing on top of that, he felt the old method of build framing a little off wall (air space) then put the trusty Fiberglass insulation in and complete with covering of plastic was just perfect.
So in the interest of science I made a small section of his perfect wall and placed it against a part of my block, bear in mind my basement looks very dry. After leaving this for month and half I just checked it last Friday when I had contractor here doing estimate on ongoing rim joist problem (don't ask).
Contractor was admiring my rigid foam work done so far and how he agreed this was better than old method so I checked the little science project and found it was already starting to show signs of mold, we were a bit surprised it occurred this fast so one can only imagine how many new bacterial friends you will gain in a few years.
Now of course because I didn't get too technical and make full tall section to include the above grade area and then factor in the whole cold/warm or warm/cold thing of above grade and below grade creating condensation and adding more moisture to the experiment.
Naturally when I excitedly told my wife of my findings she insisted I get rid science project immediately. Darn, better not tell her about the cheese to penicillin thing I'm trying in fridge.
From my research plastic in a basement wall is a very bad idea. A good test is to tape a piece of aluminum foil or plastic to the wall and see if any water condenses behind the plastic after several days.
This is a good website to do some research for the best practices based on science and not seat of the pants experience.
Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.
My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Yes, I also agree that plastic is bad idea and that was part of point of experiment to prove to my old school contractor buddy that this old method will eventually have issues...my experimental framed wall used pressure treated sill,standard studs,fiberglass insulation and 6mil plastic as vapor barrier. Spaced it about 3/4 inch from block and have seal around it so there was no wide open gap to rest of basement...believe this to be how many basements have been finished in the past. Did this test piece to check how long old way would take to grow mold. Also to show that the building science methods do hold water so to speak, which is the route I'm taking.This message has been edited. Last edited by: measure2,
measure2, were you able to move any of the rigid foam to see if you have mold growing on the surface that touches the block/concrete?
The previous owner of my house hung poly behind the fiberglass. There are areas where I can see the poly and I see mold on the surface that touches the block. I would suspect the same thing would happen with rigid foam touching or nearly touching the block/concrete.
Sturdynail, I had put up some of the rigid foam boards on walls (4x8 boards) and only got mold on temporary wood spacer to raise foam off slab a 1/2 inch or so.I had left spacers in place while I was away and when I removed wood scrap spacers the one spot that sometimes shows a tiny bit of moisture had already produced quite a bit of mold. The foam board doesn't contain anything for the mold to feed on so there shouldn't be any on that, wood though is a different story. Bear in mind most people that have seen my basement consider it dry so imagine what happens to those who frame up theirs the old way and have any minor moisture.They are going to to have some serious hidden mold problems from what I have found in just a short term experiment.
For general message board help, click the tab labeled "Tools," and choose "Help" from the dropdown menu.