I've got water damage on some of my siding due to improper installation. As you can see from the picture, the rain water sits right on the metal and soaks into the 3/8" siding. My thought is to use a circular saw with fence, set depth under 3/8", and score a 1.5" stop off the bottom and use utility knife to finish it. Since this siding is fiber board - not cement - I will need to seal the bottom after the cut. Does this work? Or does someone see any issue here? Anyone know where I can get replacement panels for this siding?

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2 Answers 2


Your approach has it merits. I would not cut an 1 1/2" off, 1" at the most. Yes you must paint the raw edge after you cut it, and believe me you will not find cutting the edge very straight forward. You must have a way in place so the saw will not roll in a way so th blade cuts all the way through. No easy task while the saw is cutting sideways with gravity working against you.

The flashing, since I can't see the top, I would presume the height under the siding may not be more than 2". Cutting 1" or more is pushing it, I would cut less if it didn't hinder painting it, and with that, I would protect the surrounding areas and slather it on using more than one coat. Priming first, then finish coat.

  • Thanks. I was thinking 1 1/2" because that's roughly the width of the fence on the circular saw.
    – ian
    Commented May 15 at 0:00

Instead of leaving a 1" gap in the siding, I'd cut 1 1/2 inches off, prime and paint the cut edge as normal, then install a pvc board inside the 1 1/2" gap.

You will also want to flash the siding as shown here: enter image description here https://lpcorp.com/blog/how-to-install-flashing-under-siding

LP Smartside composite siding is typically available at both Home Depot and Lowes.

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