Drywall where plaster and lath were

chese79 · 10-13-2012, 03:05 PM

I am drywalling a brick basement wall where plaster and lathe had been. The brick wall has been sealed with water proof sealer so moisture is not a major issue but I am still leery of ignoring the possibility.

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

The furring 1" strips are only 3/4". So do I:

1)use doubled furring strips and 5/8" drywall with polystyrene in between strips? I want to avoid cold spots since I am in Wisconsin.

2)put the fan-fold 1/4" polystyrene across everything and then furring strip and drywall over the top?

3)Somthing else entirely?

Thoughts? Advice?

Beepster · 10-13-2012, 04:10 PM

Quote:

Originally Posted by chese79

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

hand drive · 10-13-2012, 04:15 PM

existing wood on floor, is that baseboard? thanks

chese79 · 10-13-2012, 10:40 PM

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.

**Gary in WA** · 10-14-2012, 12:40 AM

Find your Zone, two different ones for your State; http://publicecodes.cyberregs.com/ic..._11_par002.htm

Fine Zone requirements, Zones 4-8 = R-10 foam board, OR R-13 cavity insulation; http://publicecodes.cyberregs.com/ic..._11_sec002.htm

Get the most for your money, compare thickness stated by temperatures in example cities given here:http://www.buildingfoundation.umn.ed...timum-main.htm

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

Gary

**Gary in WA** · 10-14-2012, 06:56 PM

"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

Beepster · 10-15-2012, 12:34 PM

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

B

chese79 · 10-18-2012, 09:40 AM

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.

**Gary in WA** · 10-19-2012, 04:20 PM

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/docum...wall-approach/

Gary