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Patching fiber cement siding

guyatwork | Posted in General Discussion on August 13, 2005 02:47am

HVAC guys came out and tore up the fiber cement siding in 2 places.  One place I replaced 2 “boards” and life is good.  Other place they drilled a ~1″ hole thorough the sidewall, (and siding) for a gas pipe and then decided it need to be a few inches lower.  I’m backcharging the HVAC company, but the second area is the problem.

The misplaced 1″ hole is through a “clapboard” that also has the gas pipe and a large electrical line running through it for the HVAC electric supply.  The elect disconnect is mounted where the electrical (10/3?) comes through the sidewall.  So, in order to replace this 1 piece of siding, it would involve both electrical and gas piping work – neither if which I’m licensed to do.  I could probably wing it on the electrical but I don’t mess with gas piping.  Also, if I call the HVAC company back in, they will send the same crew – who are NEVER going to work on any of my houses again… 

So, can I putty the 1″ hole somehow?  I was thinking of using bondo… Thoughts form anyone with first hand experience or specific data?
 

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  1. User avater
    MarkH | Aug 13, 2005 04:19pm | #1

    I don't have any experience or specific data, but I think I would find something to cover the hole, rather than patching it.

    1. User avater
      Huck | Aug 13, 2005 05:27pm | #4

      That's my thinking: depending on the location, maybe something like a j-box cover, a desktop cable grommet (I think some of them come with a solid plug), a dryer vent cover over a plug, or who knows? - a trip to the hardware store might inspire any number of options.View Image

      1. guyatwork | Aug 14, 2005 12:02am | #7

        The plug thing I hadn't thought about.  I'm gonna try filling it, but just in case that doesn't work, I'll see what kind of plug I can find while I'm at the store.  

        Two things I left out are: 1) it is smooth Hardi plank - not textured and 2) the gorillas filled the hole with silicone caulk, which I can probably just push through. 

        Edited 8/14/2005 9:09 am ET by Matt

        1. User avater
          aimless | Aug 14, 2005 07:51am | #8

          Not a pro, so this is probably a screwy idea, but what about a dutchman repair? I believe that Hardiplank is not tapered, so it would just mean cutting a square around your hole, cutting another square of the same material and then gluing it in, followed by prime and paint. That way the materials are perfectly matched as opposed to using a plug made of another material.

  2. joeh | Aug 13, 2005 05:04pm | #2

    Got any Happy face stickers?

    Joe H

  3. Notchman | Aug 13, 2005 05:17pm | #3

    I always block out for penetrations, for bases for light fixtures, etc.

    In your case, you can use a diamond saw on a 4 1/2" grinder, cut a nice square (or whatever shape you desire) out around the offending area, cut a block to fit it (a piece of Azek board is a decent choice), drill a hole just over the size of gas pipe, then slice the block in half through the hole then slip the two halves into your siding cut out and around the pipe.

    I would "glue" it in with something like Vulkem 921 and nail it with finish nails.

    Prime the cut edges of the F/C, than caulk the seams between block and siding.

    Paint to suit.

  4. TJK | Aug 13, 2005 09:23pm | #5

    A 1" hole? Just use epoxy or bondo to fill it and before it sets drag a wide putty knife across the grain to pattern the filler. After you prime and paint, it will hardly be visible.

  5. TRIGGER | Aug 13, 2005 11:23pm | #6

    Pour-rock (pour stone) is a cement product that you can do wonders with.

  6. Waterbear | Aug 14, 2005 04:19pm | #9

    I was told by the James Hardi (unofficially -of course) that the brown bag Durabond works well for patching or smoothing. I think the stuff says on the bag that it can be used for patching concrete in limited applications. If you do go that route, you might want to get some of that alkali-resistant joint tape to reinforce any larger gaps.

    1. guyatwork | Aug 14, 2005 06:18pm | #10

      Is "brown bag" for exterior use?  I'm no mud expert... :-) 

      1. Waterbear | Aug 15, 2005 04:36pm | #12

        Here is all I could find on the James Hardie website:"Dents, chips and cracks can be filled with a cementitious patching compound."Hope it helps...

      2. timkline | Aug 16, 2005 09:32am | #17

        No.

        Durabond is not for exterior use.

         carpenter in transition

  7. fartherhome | Aug 14, 2005 06:35pm | #11

    Make a plug from scrap hardie plank with a hole saw and glue it in,then bondo

  8. User avater
    Soultrain | Aug 15, 2005 05:04pm | #13

    Just put an exterior outlet there.  That way if someone ever has to work on the HVAC in the future, they have a convenient place to plug in.

    1. guyatwork | Aug 16, 2005 02:36am | #14

      I am not a licensed electrician and do not do electrical work on other peoples homes.  I guess part of producing quality includes following the rules.  It is an intregueing thought though.  Thanks.  Also code requires an outlet within 25' of the HVAC unit - there is one about 8' away, and just around the corner.

       

      1. IdahoDon | Aug 16, 2005 03:24am | #15

        I wouldn't hesitate to use bondo on a 1" hole.  It is usually a good idea to use air to blow off any loose dust first and work (rub with stick) the bondo into the edges of the hole to be filled for good adhesion.  On larger holes a tile nipper works well to rough out a "plug" patch and then bondo it in place.  When working with bondo on exterior surfaces a sharp carbide scraper will plane down the high spots well enough to be undetectable once painted.

        Cheers, Don

        1. User avater
          Huck | Aug 16, 2005 05:58am | #16

          Don - I had a prehung metal clad exterior door (foam core) blow over on a jobsite and dent, before I had a chance to install it. I used an automotive putty similar to bondo to build the dent back up, several coats and lots of sanding. It turned out great - primered and painted you can't even tell, even after several years now.

          1. IdahoDon | Aug 21, 2005 04:08am | #18

            Yep, Bondo sure is great stuff.  Minwax "high performance wood filler" has mixing directions that are word for word what Bondo has on its cans so it seems to look, smell, mix, and read like Bondo, so that's probably exactly what it is. *grin*  Who would have thought woodworkers would pay 4x the price for this stuff in a different can. 

            In an autoparts chain store I came across a Bondo-like filler called "Royal Gold" or something along those lines.  It has a tan color that is more user friendly for most word working.

            Cheers,

            Don

  9. EricS | Aug 21, 2005 02:08pm | #19

    Do what fatherhome advised - patch it with a hole saw made plug and glue/fill with the Minwax HP filler.  Just make sure you rough up the existing hole well.

    While I agree with Don that the Minwax has the look, smell, and feel of "Bondo", I just believe it's a little different but . . .

    I have successfully patched beaded, smooth FC with cut pieces and the Minwax.  After sanding and painting, you would be hard pressed to know it was repaired.

    Eric S. 

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