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Community and Q&A

Retail Source for Large(ish) Square Mounting Blocks

pjpfeiff | Posted in General Questions on

I am installing Lunos e2 HRVs on a house with vinyl siding.  Firstly, are mounting blocks the correct means of finishing the exterior penetration?  If so, any suggestions of finding a mounting block that has the same width and height (like a square or regular octagon) whose interior box has dimensions > 6 5/16″?  I found this:

However they either sent me the wrong thing or its description is wrong/confusing.  In any case, I think the internal box of the right item is probably too small (which is a dimension that the specs do not seem to list).  Any suggestions?

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  1. Expert Member
    Peter Engle | | #1

    For off-sized mounting blocks, you can make your own out of PVC trim stock of an appropriate size. If you really wanted to machine in the grooves for the vinyl siding terminations, you could do that. But you can also wrap the block with vinyl J-bead to capture the vinyl siding edges. It's done all the time.

    You also need to seal the tube to your air & water barriers. Use Roflex or QuickFlash gasket kits for this.

    1. pjpfeiff | | #2

      Thanks, strangely I've been unable to find any examples of this online even I've seen it mentioned elsewhere. Anyway, I *think* I know what to do.

    2. Expert Member
      BILL WICHERS | | #3

      It would be easy to use a router to mill out underneath the face of the block around the edge to clear the siding. That would eliminate the need for J bead and would give a somewhat cleaner look.

      I like the idea of machining a groove for the siding, but that sounds like it would be difficult to do well without a jig.


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