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Community and Q&A

Missed mounting blocks on Hardie siding

bongo30 | Posted in General Questions on


Our siders missed 2 mounting blocks while installing Hardie siding. Is there a way to fix this now? The siding cannot be uninstalled, and I’m worried that any box we install on top now would not be weatherproof. The siders recommend just caulking the gap, but I’m afraid it will not look good and the caulk will disintegrate over time. 

Any recommendations as to how you would fix this? 

Thank you,

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  1. Expert Member
    Akos | | #1

    Depends if there is strapping behind there. If there is strapping there, you can carefully cut the hardie to the size of the mounting block, slip a length of drip edge under the siding on the top and install the mounting block.

    If these are not visible or no strapping behind, I would caulk and not worry about it. This is one benefit of a rain screen, even if a bit of water does make it behind the siding, it won't cause problems.

  2. Expert Member


    Since you've got a rain screen system with your furring strips, I think you're fine with just neatly caulking that gap. If you want a little extra insurance, and don't mind a bit of flashing, you can slide a short section of Z flashing up above the pipe, in between the overlap of the two boards, so that it directs the water running down the wall out and over the pipe just a bit. If you trim them nice and they're the same length, it'll look like they're supposed to be there.

  3. bongo30 | | #3

    Perfect! Yes, we have the strapping under it, I’m attaching a picture of what it looks like before siding was installed. Thank you Akos and Kyle!

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