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-   -   extent of the vapor barrier (http://www.diychatroom.com/f19/extent-vapor-barrier-170244/)

hswerdfe 01-27-2013 09:48 AM

extent of the vapor barrier
 
1 Attachment(s)
I have put the vapor barrier and drywall up in my basement. as well as some new basement windows.
but I have not finished up to and around the window.

since I put up the vapor barrier (4 days ago) I am getting a lot of frost on the foundation edge around the window.
(But we have also had a cold snap during that time, so it could be that.)

Do I need to extend the vapor barrier along the window ledge to complete the envelope?

and should I maybe try to put a half inch of insulation up first?

thanks

Attachment 64462

joecaption 01-27-2013 09:53 AM

High humity and air leaks around the window frame would be my first guess.
I would have used low expanding foam instead of fiberglass around those windows.
Compressed fiber glass is useless as insulation.

hswerdfe 01-27-2013 10:27 AM

Hey Joe I used "GreatStuff Windows and Doors" between the concrete and vinyl window (yellow layer). I used "GreatStuff Big Gap" between the concrete and outer framing members White layer. And I used Roxul insulation in the wall cavity (not compressed).

No fiberglass was used.
As for humidity, my dryer is right next to it so that might have some effect. and my dehumidifier tells me it is currently 60% humidity, which is a little high. as I try to keep it around 45% or 50%.
Note: it is also -16C (3F) which may cause some issues.

What about extending the vapor barrier from the tape to the window border? and or putting 1/2" of foam around the window?

jklingel 01-28-2013 12:34 AM

where are you? is the basement below grade, or above? the vapor barrier is possibly a very risky venture, depending on answers to above. IF NEEDED, yes, the vb should be entirely one piece, floor to ceiling, as best as is possible.

hswerdfe 01-28-2013 08:01 AM

where are you?
- Ottawa
is the basement below grade?
- ground level just below that window which is about 5' off the basement floor.

Why is a VB in the basement risky? everybody I have known puts one in.

russiand 01-28-2013 09:26 AM

The current trend is
 
Not to use vapor barrier at all. If you do some research it turns out that it is likely to trap moisture and actually cause more problems than it can solve. The idea is to create a breathable system that can dry out to the inside. Most builders still use the vb method but that does not mean that they are right.

jklingel 01-28-2013 03:28 PM

your gov't published a report on this, and various people have used it to say "see. it's ok for a vb below grade". however, at in the conclusions of that report they mention that the test wall w/ the vb below grade was damp. buildingscience.com will have info about this, too. a cat on here claiming to be canadian said the regs actually say (not exactly) "you need a vb unless you can show that your system will stop air movement." vb's below grade is old, old thinking.

hswerdfe 01-31-2013 10:03 PM

do you have a link to the report?

jklingel 01-31-2013 10:17 PM

no link, but this will help you find it: final report, UNDERSTANDING VAPOUR PERMEANCE AND CONDENSATION
IN WALL ASSEMBLIES
for
Canada Mortgage and Housing Corporation
Halsall Associates Ltd. and University of Waterloo
May, 2007

This is from section 6.2, maybe of the Conclusions: This research suggests that interior vapour control at the lower portion of the basement wall is unnecessary or inhibits drying. These locations experience temperatures that are similar to geographic locations that require no vapour control layer. The monitored data shows that an interior impermeable layer at this location reduces drying and results in longer periods of elevated humidity at the concrete-insulation interface. Simulations showed that performance at the lower portion of the wall improves with increasing vapour permeability. Furthermore, simulations of ventilating the basement with exterior dewpoint air showed negligible accumulation, which could dry in the winter. Instead of a vapour barrier, these results suggest that an air barrier might be all that is required to control condensation in the below-grade portion of the basement wall.

Canucker 02-01-2013 07:28 AM

Quote:

Originally Posted by jklingel (Post 1104259)
a cat on here claiming to be canadian said the regs actually say (not exactly) "you need a vb unless you can show that your system will stop air movement."

Claiming to be canadian? Ouch, j. haha
It's in the national building code of canada, section 5, I believe. Ontario's section of its code is section 5.5.1.1, sentence 3.
http://www.e-laws.gov.on.ca/html/reg...s_060350_e.htm

This one's for you, j :laughing:
http://www.youtube.com/watch?v=BRI-A3vakVg

jklingel 02-01-2013 02:28 PM

Canucker: OK, OK, I believe you now. Thanks for the link to the study. As for the commercial, uh, wth? It sounds like that cat has some misplaced aggression based on misinformation, or else it is just a tongue-in-cheek thing. OK, he's Canadian and I'm not. So? Neither one of us are Norwegian or Ethiopian. Now what? There is a lot of strange stuff on youtube.

Canucker 02-01-2013 03:05 PM

Quote:

Originally Posted by jklingel (Post 1107317)
Canucker: OK, OK, I believe you now. Thanks for the link to the study. As for the commercial, uh, wth? It sounds like that cat has some misplaced aggression based on misinformation, or else it is just a tongue-in-cheek thing. OK, he's Canadian and I'm not. So? Neither one of us are Norwegian or Ethiopian. Now what? There is a lot of strange stuff on youtube.

Haha, It's an old beer commercial from, I guess, quite a few years ago now. Sold a lot of crappy beer for them up here. All tongue in cheek.


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