Go Back  DoItYourself.com Community Forums > Interior Improvement Center > Insulation, Radiant and Vapor Barriers
Reload this Page >

Insulating basement with interior french drain and vapor barrier.

Insulating basement with interior french drain and vapor barrier.

Reply

  #1  
Old 05-19-17, 11:32 AM
S
Member
Thread Starter
Join Date: Apr 2008
Posts: 32
Received 0 Votes on 0 Posts
Insulating basement with interior french drain and vapor barrier.

I own a 1940s home with a basement. The walls in some areas of the basement were bowing, which is common here in western Pennsylvania (zone 5) due to wet soil and collapse of the terra cota exterior footer drainpipe. Sooo we all get interior french drains...

I want to furnish the basement again by framing, hanging drywall and placing an engineered wood floor.

I now have an interior french drain that was installed 2.5 years ago and there is minimal water in the sump, the pump only ran once - when I poured water into it to test it. There is a plastic vapor barrier nailed against the wall with a few plastic washers. The barrier runs as a 4 ft sheet with horizontal seam that is not taped or otherwise sealed.

How should I insulate the basement? I see options as open cell spray foam on the vapor barrier, XPS board against the vapor barrier or fiberglass bats in the walls with a gap between the bats and the vapor barrier. As I understand it, I want to avoid wicking and avoid having wet materials for mold growth. The sump for the French Drain was placed ~5 inches from the foundation wall... so I don't have too much space to build a wall while maintaining sump access.
 

Last edited by Soparklion; 05-19-17 at 01:29 PM.
  #2  
Old 05-19-17, 03:17 PM
S
Member
Thread Starter
Join Date: Apr 2008
Posts: 32
Received 0 Votes on 0 Posts
Update: The sump sits 5 inches from the foundation wall, so I don't have a tremendous amount of space for insulation. The gap between the sill plate and the studs is ~1.5 inches at the base, but 3/4" where the wall bows inward - note that there are carbon fiber straps that limit wall movement.

How should I insulate the basement? I see options as open cell spray foam on the vapor barrier or fiberglass bats in the walls with a gap between the bats and the vapor barrier. I don't have space for XPS unless I relocate the sump or figure out some way for that last 2 feet of wall not to cover the sump... By that same measure, I also won't have 2 inches of foam between the studs and the foundation wall...
 

Last edited by Soparklion; 05-19-17 at 03:39 PM.
  #3  
Old 05-19-17, 04:27 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
Just so we all can talk about the same thing, and to allow us to see what you see, could you post a couple of pictures of the basement? http://www.doityourself.com/forum/el...your-post.html
 
  #4  
Old 05-20-17, 08:47 AM
S
Member
Thread Starter
Join Date: Apr 2008
Posts: 32
Received 0 Votes on 0 Posts
pictures

thank you! I can't rotate my pics...

A DAP technical advisor said that I should shoot the bays with foam and that the vapor barrier will protect the foam and studs from moisture but that I should seal the seam in the vapor barrier. I suppose that I should foil-tape the gap at the beam and at the junction with the chimney/hearth as well.



Name:  1.jpg
Views: 2806
Size:  28.1 KB



Name:  2.jpg
Views: 1396
Size:  24.5 KB



Name:  3.jpg
Views: 1140
Size:  23.6 KB


Name:  5.jpg
Views: 1990
Size:  22.1 KB
 

Last edited by chandler; 05-21-17 at 11:36 AM. Reason: correcting picture position
  #5  
Old 05-21-17, 06:15 AM
Marq1's Avatar
Member
Join Date: Sep 2016
Location: USA MI
Posts: 7,091
Received 460 Votes on 429 Posts
What exactly is the material hanging on the walls.

Here is another current post regarding basements, I dont see why that would not apply to you with the exception of that material on the walls.

http://www.doityourself.com/forum/ba...finishing.html
 
  #6  
Old 05-21-17, 10:50 AM
S
Member
Thread Starter
Join Date: Apr 2008
Posts: 32
Received 0 Votes on 0 Posts
The referenced thread...

just says that you shouldn't close off a space and that you should deal with existing water issues. I believe that the interior french drain has addressed the water issues. The water table is fairly high and there will always be water around the footer that will leach upwards into the basement walls, but the drain system removes it.

I can provide dehumidification and circulation.

The Vapor Barrier is present and it will stop spray foam (my planned solution) from soaking up water off of the foundation wall and transferring it into my framed wall. There will be enough insulation that the surface of the foam will be at the interior room temperature rather than the subsurface ground temperature to eliminate condensation on the surface of the foam.
 
 

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