Go Back  DoItYourself.com Community Forums > Interior Improvement Center > Basements, Attics and Crawl Spaces
Reload this Page >

Basement Insulation / Moisture Barrier Design Question

Basement Insulation / Moisture Barrier Design Question


  #1  
Old 08-21-14, 01:05 PM
M
Member
Thread Starter
Join Date: Aug 2014
Posts: 2
Received 0 Votes on 0 Posts
Basement Insulation / Moisture Barrier Design Question

I'm finishing my basement and having trouble deciding what type of insulation and moisture barrier I need.

I'm not a big fan of furring strips as that requires drilling holes and pounding nails into poured concrete. Could I go with rigid foam board for the moisture barrier, then build 4" framed, insulated wall against that? Or is that kind of overkill?

Basement:
Poured concrete, central Kentucky region, 7 years old. The wall at the rear of the house is completely above ground, the wall at the front of the house is completely below ground. I have zero moisture problems currently, but have yet to tape plastic to the wall.
 
  #2  
Old 08-21-14, 02:20 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,524
Received 37 Votes on 34 Posts
It always seems that once someone assumes they don't have a moisture problem, as soon as they finish the basement the end up with one. I'll be quick. Moisture comes in two forms, liquid and vapor. Liquid you can see, but the vapor passes right through the concrete and evaporates before it accumulates at the surface. Even if the plastic rest indicates no moisture vapor, it is there.

But, your proposed wall assembly is just what you want, just be sure to use a rigid foam board with a small amount of permeability (pink or blue). What you want is a wall that will dry to the inside, since it can't dry to the outside. That also means no vapor barrier, like plastic, on the inside.

I'll add a couple of related links. Note photo #4 in the first link.
BSD-103: Understanding Basements — Building Science Information
Vapor Barriers or Vapor Diffusion Retarders | Department of Energy

Bud
 
  #3  
Old 08-21-14, 06:59 PM
C
Member
Join Date: Jan 2014
Location: usa
Posts: 466
Received 1 Vote on 1 Post
Do you have a clue as to what was done on the exterior of the wall in the process of original construction? Was there a water/vapor barrier membrane or coating applied to the exterior in a workmanlike manner? if so, do you know what it is?

What may be the best interior system could be influenced by what was done on the exterior.
 
  #4  
Old 08-22-14, 07:30 AM
M
Member
Thread Starter
Join Date: Aug 2014
Posts: 2
Received 0 Votes on 0 Posts
I'm pretty sure that no coating was applied to the foundation. It feels like just straight concrete.

Thanks for the links! Will definitely read.
 
  #5  
Old 08-22-14, 12:55 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,795
Received 8 Votes on 8 Posts
There should be no VB on walls below grade because they cant dry out
 
  #6  
Old 08-22-14, 01:39 PM
C
Member
Join Date: Jan 2014
Location: usa
Posts: 466
Received 1 Vote on 1 Post
InSoFast | Engineered Simplicity
InSoFast | Engineered Simplicity
InSoFast's Engineered Panels provide continuous insulation, built-in framing, and moisture control for both new and retrofit construction projects.

You could check these out. They would provide a level of insulation that is vapor permeable and give you an attachment opportunity for drywall.

If your desire is not to finish the space, you would have to cover it with a surface material that meets fire spread regulations for your area, maybe drywall but also check "FSK" fire resistive foil/kraft laminate that usually satisfies inspectors.

There are also a few liquid applied materials available to create a moisture barrier within the concrete, "xypex" is one such product. There are others, I'll check my records later. Some products give liquid water control while others give vapor control. Ideally, one that does both is something that would be of the greatest appeal to you.

If there is any chance that you might be apt to experience water issues from exterior grading or other issues, you should most definitely deal with the source of those issues first. Saturating a wall with no opportunity for drying is never prudent.
 
  #7  
Old 09-14-14, 07:49 AM
M
Member
Join Date: Sep 2014
Location: USA
Posts: 1
Received 0 Votes on 0 Posts
existing, old home

I am considering adding insulation to the "basement" of our 40 yr old home. The first room to tackle has old wood paneling and 2 walls are exterior and below ground (one of these walls is 1/2 below ground, with a window toward the top). 2 walls are interior.
My primary reasons are temperature and moisture - the room is always damp and cold. I highly doubt there is any insulation currently behind the paneling and am pretty sure if I remove the paneling I will see concrete block.
So, should I use a rigid foam board or some other kind of barrier first, then put in a fiberglass insulation? If so, does the foam simply go between the studs (I haven't removed the paneling but am hoping to find 2x4s behind it.)

This will be a sort of test-run for the rest of the basement. There is one other bedroom plus 2 other rooms, all with the old paneling and no insulation.
Thanks for any advice (not a builder, just a homeowner with a high heating bill!)
Monica
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: