# Drywall where plaster and lath were



## Beepster (Oct 19, 2009)

chese79 said:


> There is existing wood molding attached to the floor giving me only 1.5 inches for furring, polystyrene and drywall.


What exactly do you mean by this? I am in Minneapolis and am doing 1" XPS behind full 2x4 framing. Not sure what you mean by "existing wood molding".

What sealing the brick walls is not a fix all. It only directs the moisture downward. How is the landscaping outside? Ever had any moisture before?

B


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## hand drive (Apr 21, 2012)

existing wood on floor, is that baseboard? thanks


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## chese79 (Oct 13, 2012)

Yes , wood molding= baseboard. For the three years I have lived here, no moisture problems. The landscaping and pitch is adequately away from the house. Very sandy soil so it drains quickly. Floor is sealed abspestos.


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## Gary in WA (Mar 11, 2009)

Find your Zone, two different ones for your State; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_par002.htm

Fine Zone requirements, Zones 4-8 = R-10 foam board, OR R-13 cavity insulation; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

Get the most for your money, compare thickness stated by temperatures in example cities given here:http://www.buildingfoundation.umn.edu/FinalReportWWW/Chapter-5/5-optimum-main.htm

Or figure "dew point" with RH in basement (temp. the f.g. cavity insulation wets from condensation); http://www.greenbuildingadvisor.com/blogs/dept/musings/are-dew-point-calculations-really-necessary

Gary


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## Gary in WA (Mar 11, 2009)

"I am in Minneapolis and am doing 1" XPS behind full 2x4 framing"---------

Beepster, be sure to control the indoor RH to below 41% @ 70* for your 6 months of the year against condensation with a dehumidifier to be safe from condensation and get full value of the f.g. cavity insulation. I don't know how your post about thickness of f.b. got past me last year... 2" f.b. would give up to 51%RH at 70*.

Gary


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## Beepster (Oct 19, 2009)

Thanks GBR. I monitored the humidity level this summer and am comfortable with the choice I made.

B


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## chese79 (Oct 13, 2012)

Ok, so it sounds like there is no issue having a furring strip over the top of XPS? It is better to have more XPS in between the furring strips or is an air gap better? I would think more XPS, but I am a total newb to this stuff.


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## Gary in WA (Mar 11, 2009)

You think correctly; air gaps are never good; http://joneakes.com/jons-fixit-database/743

Can foam the XPS to the concrete floor, tape/mastic all seams, ADA the drywall installing some filler insulation in the furring cavities; http://www.buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach/

Gary


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