| Author |
Message |
David G. Axt, CDT, CCS, CSI, SCIP
Senior Member
Username: david_axt
Post Number: 2006
Registered: 03-2002
| | Posted on Thursday, March 09, 2023 - 11:33 am: |    |
I received an interesting email from Stego asking the question whether the vapor barrier should go above or below the underslab insulation.
What do you recommend?
David G. Axt, CDT, CCS, CSI, SCIP
Specifications Consultant
Axt Consulting LLC |
Phil Kabza
Senior Member
Username: phil_kabza
Post Number: 750
Registered: 12-2002
| | Posted on Thursday, March 09, 2023 - 12:25 pm: | |
I have always expected the underslab bapor retarder sheet to be below the underslab insulation, so that it would technically protect the insulation from the higher moisture content of the soil. I don't see any advantage in placing the insulation directly on the soil.
Phil Kabza FCSI CCS AIA
SpecGuy Specifications Consultants
www.SpecGuy.com
phil@specguy.com |
David G. Axt, CDT, CCS, CSI, SCIP
Senior Member
Username: david_axt
Post Number: 2007
Registered: 03-2002
| | Posted on Thursday, March 09, 2023 - 02:07 pm: | |
Phil,
Do you specify the insulation joints to be taped to prevent concrete from oozing down the open joints?
David G. Axt, CDT, CCS, CSI, SCIP
Specifications Consultant
Axt Consulting LLC |
Phil Kabza
Senior Member
Username: phil_kabza
Post Number: 751
Registered: 12-2002
| | Posted on Thursday, March 09, 2023 - 03:01 pm: | |
Doesn't seem like a bad idea.
Phil Kabza FCSI CCS AIA
SpecGuy Specifications Consultants
www.SpecGuy.com
phil@specguy.com |
RH (Hank) Sweers II RA SCIP
Senior Member
Username: rhsweers2
Post Number: 33
Registered: 08-2005
| | Posted on Saturday, April 01, 2023 - 06:25 pm: | |
David:
Per Joe Lstiburek and the "Perfect Wall" (or in this case, the "Perfect Slab"), the insulation control layer is at least graphically indicated to be below the vapor-control layer. But it's sort of mixed in with the other "control layers", so for all I know (and I don't really) it could be interchangable . . . re:https://buildingscience.com/documents/insights/bsi-001-the-perfect-wall |
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