XPS tape

Sukhoi29SU

Any recommendations on the best tape to use for foamular 250 xps foam for under slab radiant application? I’ve read about some pricy tapes (Siga wigluv, for instance) that might work nicely- but I don’t necessarily need to spend the extra Money on a tape designed for air tightness for wrapping a house since this will only be used to tape the seams for foam laying on the ground. Thanks in advance

JackW

When I installed my radiant heating system in my Morton building in 2005 I taped all my 2" pink Styrofoam together with duct tape.

Sukhoi29SU

I was hoping to get a response like that. I was considering doing the same.

ScottSecor

I also used a good grade of duct tape when I did mine and a few customers over the years.

GroundUp

Do you have a vapor barrier underneath or are you using the foam as a barrier? If the latter, duct tape or anything else not designed to be used as a barrier is not going to be one and "Tyvek tape" is a necessity. If you have poly underneath, use whatever you want or don't tape it at all

Sukhoi29SU

@GroundUp thanks for the responses , guys. I’ll be using a 15mil stego wrap vapor barrier underneath the xps foam. (I asked about where to put the vapor barrier in a recent thread here... I had received some recs to place it above the foam). Anyway , You make a good point- I cant think of a reason to even tape the seams based on the vapor barrier underneath. I might use a good duct tape - just for peace of mind...

mattmia2

thick, quality packing tape with urethane adhesive may perform the same as the official tyvek tape.

rick in Alaska

We put the vapor barrier under the foam, and I have never seen anyone tape the foam.
Rick

Ironman

We've come to the place that we use Creteheat board almost exclusively. It serves as the vapor barrier and insulation and drastically reduces the installation time.
That being said, if you're gonna use another method, I wouldn't skimp on anything - especially tape. How much would that really save of the total job cost?
Remember: what you're doing is virtually forever. Once the concrete is poured, you don't get a second shot at it.

JackW

@rick in Alaska what keeps the concrete from getting under the foam and floating it to the top. Once that happens you would never get it back down.

rick in Alaska

Well, the foam joints are fairly tight to begin with, and when they start pouring the concrete, the weight of the concrete holds it down. I have never known of anyone who had the foam board float up.
Rick