Framing Block Wall (not a basement)

Reply

  #1  
Old 01-14-09, 05:30 AM
Member
Thread Starter
Join Date: Jan 2009
Posts: 3
Framing Block Wall (not a basement)

We have an ugly cement block wall that we'd like to frame, because A) it's uninsulated and B) it's U-GLY. I've seen a lot of posts about basements, but this isn't a basement. It's an above grade wall. Not sure if that makes a big difference or not.

My understanding is with CMU the primary concern is moisture. I've read various 'solutions' on how to frame a wall of this type. Everything from DryLocking, to 1" offsetting, to vapor barriers, to using metal studs instead, etc. I'd appreciate some guidance.

Our criteria are:
The wall has a window, I need the wall appearance to remain 'thin' so the window doesn't look freakish. So I think limiting the framing to 2x4 and R-13 batt makes sense (feel free to contradict me). I know, insulating sheeting would be thinnest, but the R-value would be too low for NY state, and it would cost way too much --sheeting looks to be 3x 4x more expensive. Sheetrock will be used to finish the wall.

So, what are the issues? How to deal with the moisture? Offsetting the wall would add thickness, not something we want. So apply a vapor barrier between the frame and concrete? (I should say, the concrete is painted; is that enough of a barrier?)

One fact that is pertinent is that I'm planning to *eventually* have the outside of the wall stucco'd with EIFS to add exterior insulation and make it oh-so-pretty. I'm curious whether having insulation on both the outside and inside will create a 'vapor trap' and cause problems.

Damn moisture is a pain. I hope this isn't too challenging. Thanks
 
Sponsored Links
  #2  
Old 01-14-09, 06:20 AM
Member
Join Date: Feb 2006
Location: New York
Posts: 174
The fact that your wall is above grade means you'll need to insulate floor to ceiling. I would waterproof the wall, with Thoroseal or Drylock first. This can't hurt.
Frame a 2x4 wall floor to ceiling with PT sole plates, an inch off the face of the block. Insulate with R-13, sheetrock, tape ,paint. There is really not much you can do about the window opening becoming deeper. That's what it is. Just finish it nicely.
 
  #3  
Old 01-14-09, 11:18 AM
Member
Thread Starter
Join Date: Jan 2009
Posts: 3
i looked it up, drylok won't work over paint - since this wall is already painted over.

Q. Can DRYLOKŪ Masonry Waterproofer be used over paint?
A. Yes and no. DRYLOKŪ may be used over any other cementitious type waterproofing paint in good, repaintable condition, either inside or outside. However, DRYLOKŪ cannot be used over an oil or latex-based paint on the inside of a building. DRYLOKŪ will adhere to these paints, but if it cannot get into the pores of the masonry itself, it will not waterproof.


The floor is wood board, I don't believe it's necessary to use PT wood, or should I use it anyway due to the presence of the concrete?

Instead of using a 1" offset (again, we'd like to keep the wall thin), could I do no-offset and put some plastic sheeting on the back of the frame? ...or paint the back of the untreated lumber with a sealer?
 

Last edited by TheCW; 01-14-09 at 12:22 PM.
  #4  
Old 01-14-09, 04:05 PM
Member
Join Date: Feb 2006
Location: New York
Posts: 174
Seeing as how your foundation is above ground, a lot of the usual basement considerations don't apply. If it was me, I would still put Drylock or Thororseal on the foundation wall. It's your call. I would maintain the 1" space to keep the insulation off the concrete. An inch isn't going to kill you. I don't like plastic vapor barriers in this situation. I think that it will trap moisture against the block. If your sole plates are not directly on the slab, I guess you don't need to use PT. I've never done it that way.
 
  #5  
Old 01-14-09, 08:12 PM
Member
Thread Starter
Join Date: Jan 2009
Posts: 3
This post will probably answer anything anyone on the forums needs to know about vapor barriers. I was lucky and found a article that is HIGHLY educational on the topic of vapor barriers. Totally fascinating.

BSD-106: Understanding Vapor Barriers —

According to the article, it looks like I can just frame flush to the wall and skip the vapor barriers. This is based on reviewing the document and analyzing Figure-1, 2 and 5. A) Since this is an above ground wall, the basement issues don't apply, since the wall can breath out to the exterior. B) Since the wall is painted (oil paint, which repels water) the paint itself restricts moisture coming from the outside through the cement block. Then the remaining issue is for the interior moisture to 'breath' through the insulation, so no vapor barrier needed there either. Since eventually we plan to EIFS the outside, the whole thing will end up looking like Fig-1+2 anyway.

The article implies, a resistant, but semi-permeable material would help between the wall and batt insulation -probably where the off-set notion comes from - although it may not be a necessity. I thought maybe Tyvek would work. But since in the summer it is an air conditioned space, the document says "polyethylene" (ie. Tyvek) barriers should be avoided in this case. So it needs to be something other than Tyvek, something moisture insensitive, but 'breathable'. Ideas?

Anyway, I hope I understood that thing right.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes