Hi everyone,

I am building a new home in SE Wisconsin. I am putting in Hydronic heat in the basement and garage. The floor is all prepped and we will be laying about 130 sheets of owenscorning Fomular 250 2"  4'x8' sheets.

The sheets are going in well, but not perfectly flat, so we want to tape the seams up.

Do we have to use the Tyvek tape(at $13 a roll for 164') or can we use regular duct tape or something similar. I want to make it as easy as possible for my contractor to lay the PEX tubing.

There is a vapor barrier below the rigid insulation.

Thanks in advance

Steve

Any tape that sticks well and is strong should work fine in that application. Cheap duct tapes just don't have the quality adhesive to stick for very long. I have found Gorilla Tape to work very well, but it won't save you much over the cost of the Tyvek tape you listed.

If it isn't flat the substrate is the problem. There is no good reason to tape XPS in a sub-slab application with vapor barrier below. 250 is over-kill for this as well. 150 in 2" is good for any foot traffic.

You really should consider correcting the substrate issue so the insulation does lay flat. You should also consider placing the vapor barrier on top of the insulation if you plan to finish the floor anytime soon. Placing the vapor barrier below the insulation (especially on an uneven substrate) may result in water being captured and trapped between the insulation and the vapor barrier during the concrete pour that may create lingering moisture issues that may be problematic when you finish the floor. EPS would have been a greener solution than using XPS.