basement condensation woes

I'm at my wits end.
I own a 1956 ranch house in Montreal QC. Measures 60 x 30. The basement nor the house for that matter had much renovation definitly no
insulation added to attic or basement. The basment is virtually empty and the concrete has been repainted with some sort of enamel looking grey paint. The basement is about 7 foot 3 maybe 3 feet above grade. There are 12 windows. I chaulked the outside pretty well. The outside
siding is wood and in good painted shape I just sealed here and there. The weired part is that the space between the joists which appear to be
sitting on the foundation have actually been filled with concrete. I suppose they laid the joists/floor atop of the foundation and poured another layer. Can i say the joists are embedded in concrete? I just find it interesting. I recently put up 1.5" blue rigid insulation. I placed 3 sheets wide and left about 15 inches off the bottom so as not insulate the whole wall. However I put insulation bewtween the joists.
Now im seeing condensation on any exposed concrete. like just under heater vents and on windows frame edge. so i chaulked it then put some
shrinking plastic over the hole...I guess i need to chaulk the blue stuff to the wall...
You need to be very careful here Deliper. The CMHC has put out a booklet called Keeping the Heat In. They strongly recommend that you DO NOT insulate the rimjoist in cases where the joists are embedded in concrete, just air-seal the cracks. The reason is to that insulation will keep the moisture from drying and the joists will rot. Here is the link...
Be patient, this is a large PDF file, so it takes a long time to load up. The material on embedded joists begins on page 65.
For others, this material is designed for the cold Canadian climate, so
it would apply to the northern US as well.
Steve Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse
On 1 Mar 2005 04:27:20 -0800, wrote:

What is your basement's relative humidity?
tom @
The temperature of the basement is roughly 19C and 35%. The house sits on a crown so water drains away quit well I think. I guess google filters out email addy's
so here it is again.
deliperrot at yahoo dot com
Here is someother info. I took off the floor moulding on the mail floor and chaulked it I felt a draft/cold air. I still have not chaulked the rigid insulation in the basement. I placed plastic over the rigid insulation where my old crappy windows are and its still wet.
like the chaulk can't dry. I think what i need to do is make a sealed cell. The rigid insulation plus the paint act as vapor barriers. I dont want to put up plastic. because its an old leaky house and moisture is just part of the game. I also turned off my exhuast furnce
fan and turned off the humidifer. to see if it makes a difference.
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