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How are people prepping for wall penetrations?

dvaut | Posted in Mechanicals on

I am hoping to start building an energy efficient house this year with an ACH50 below 1. To achieve this I am trying to have all the penetrations figured out before I start to build. My basic wall construction will be from the outside: LP smart products over 2X4 rain screen, 3″ XPS, zip system sheathing(air barrier), 2X6 cavity with dense pack cellulose, and finally sheet rock. Since the zip-sheathing is the air barrier and the exterior surface is where the zip-tape seals to best I am trying to pre-plan all the penetrations before the exterior foam is applied. Of course the bank wants the foam/Siding on before receiving the second draw which will fund all the mechanicals which is when various penetrations must be made through the exterior. A catch 22.
I am planing on using Kaflex epdm wire gaskets for romex penetrations and running romex through the wall before the rest of the electrical. Has anyone had much experience with the epdm gaskets?
What about line sets for a ductless minisplit? I was thinking about making a sealed PVC penetration through the zip-sheathing, foam, and siding ahead of time. Then the HVAC contractor can just run the line set and electrical through the PVC without having to drill a hole later.
Then there is my concern for the range hood exhaust duct. When are builders making this penetration? I was thinking about having the insulation contractor leave that bay empty. I would use fiberglass batts in that bay which would make installing the range hood exhaust duct easier and less messy at a later time. I will probably have to seal this to the cavity side of the zip-sheathing. Any suggestions or real world experience is appreciated.

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  1. Expert Member
    ARMANDO COBO | | #1

    There are all kinds of wall flashing for penetrations on the market. Here is one of those products: Having said that, many folks use zip tape. Critical is to make the hole as tight to the pipe or wire. Foam around and flash on the outside.
    IMO, if you are using 2- 1 1/2" layers of taped XPS, with staggered seams, I would not waste the extra $10/Bd Zip OSB.

  2. dvaut | | #2

    So the tape is as effective as the gaskets? I do like the idea of the zip stretch tape. My main concern is holes that are made after the siding. I just want to have every detail nailed down before I start. Are people making penetrations ahead of time, or drilling through thick walls afterwards. It seems like having a taped PVC pipe penetration before hand to run mechanicals through and sealing the inside with can foam later would be a safer. That way I could tape it to the air and WRB. With the foam or siding on I will not have this luxury.

  3. Expert Member
    ARMANDO COBO | | #3

    I work mostly in CZ3 and 4. We typically use 1/2" and 1" foam board over plwd and then we install StuccoWrap over the foam. The holes are usually drilled before the cladding goes up. That's were the flashing or Zip tape goes on. Since all siding is installed with rainscreens, the siding installers drill to allow the wire or pipe to come through so all you show is calk or seal in the cladding. It gives it a clean look.

  4. user-1135248 | | #4

    Here's one vote for pre-doing your own penetrations in PVC or
    whatever the appropriate minimally-thermal-bridging material is.
    [Black ABS worked for me on some of the smaller diameters, too.]
    That lets you set up where and how it passes through the air barrier,
    and then all the other trades have to work around it and adapt
    gracefully to how it's set up.


  5. dvaut | | #5

    I'm my own siding contractor/GC. So I think I can work gracefully around PVC pipe. I am trying to set up the HVAC technician, Electrician, and myself for later success. The contractors will probably not be used to the level of air sealing I am trying to achieve. They will probably think I'm crazy, and shake their heads, but if I make it easy for them, there is less of a chance for mistakes.

  6. Expert Member
    ARMANDO COBO | | #6

    Its really simple... my way or the highway!!! Its always easy working with contractors if you have appropriate details in your plans and a full set of specifications that requires them to make the smallest hole needed and THEY have to seal their own hole. Don't let anyone bid unless they accept your requirements.
    Most homeowners and builders have gotten used to accepting substandard quality of work, and it shows in their jobs.

  7. Chaubenee | | #7

    I use electrical conduit with coupling ends that I set up in the concrete forms closer to the top of the foundation. I can put as much conduit onto the interior or exterior to clear the interior insulation or exterior stone cladding. I pre planned the various locations for the linesets (single 3" for 2 linesets) and furnace and hot water exhaust (also 3" sleeves for each as they are 2" PVC) and I have the locations of my sillcocks, both hot and cold running through 2" conduit as well, all pre planned. Inside I use foam and clear elastomeric caulk and I seal around the edges of the conduit on the outside of them as well. I like these penetrations to go through the top 6" or so of my foundation which is 24" above grade so that I am dealing with less holes in my mud sill area and also they are less obtrusive as well. These will literally be coming out on my granite veneer so they are better camouflaged if you will. The pic shows them in the forms before the concrete was poured.

  8. Chaubenee | | #8

    This blurry pic shows one of them after we were poured. Notice the recessed portion of the wall which has a ledge to lay the stone. Oh, and This one is slightly lower because it is a cold water sill cock, which will sit about 16" off the ground later on when we are final grade.

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