0 Helpful?

Is it necessary to tape joints in under-slab insulation?

I'm putting recycled 4" XPS under my slab. Zone 6. Do the joints need to be sealed with anything? I'll put poly on top, under the concrete.

Asked by stephen sheehy
Posted Aug 11, 2014 8:08 PM ET
Edited Aug 18, 2014 4:57 AM ET

Tags:

5 Answers

Select your preferred way to display the comments and click "Save settings" to activate your changes.
1.
0 Helpful?

Nope- the taping would have negligible value at best. The amount of thermal bypass air movement under the slab is miniscule, and the poly layer makes it air & water-vapor tight.

Answered by Dana Dorsett
Posted Aug 12, 2014 10:10 AM ET

2.
0 Helpful?

Thanks, Dana-That's what I hoped was the case. Your explanation makes sense.

Answered by stephen sheehy
Posted Aug 12, 2014 10:19 AM ET

3.
0 Helpful?

You doing one layer of 4" or 2 layers of 2"? Good to have staggered seams.

Answered by Dan Kolbert
Posted Aug 12, 2014 7:42 PM ET

4.
0 Helpful?

Dan-we're using 4".

Answered by stephen sheehy
Posted Aug 13, 2014 8:21 AM ET

5.
0 Helpful?

I used 3" XPS under my basement floor and didn't tape the seams, we did however ensure we taped the seams of the poly vapor barrier extremely well.

Answered by Anthony Hughes
Posted Aug 18, 2014 11:54 AM ET

Other Questions in Energy efficiency and durability

Foil-faced batt insulation effect on wall construction?

In GBA Pro help | Asked by Michael Kalustov | Feb 27, 15

Insulating a low-slope EPDM roof from the ceiling below

In General questions | Asked by joseph moore | Feb 26, 15

Best way to have a wood fireplace?

In Energy efficiency and durability | Asked by Clara Kim | Feb 22, 15

Converting fiberglass+plastic basement insulation to rigid foam - worth it?

In Energy efficiency and durability | Asked by Jeff Watson | Feb 28, 15

Dense packing cellulose - height of cavity

In General questions | Asked by Graham Fisher | Feb 28, 15
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!