Cutting a hole in hardie


Old 10-09-17, 07:06 AM
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Cutting a hole in hardie

Howdy folks,
I am trying to figure out the best way to drill a hole in my hardie siding to make a hole for my dryer vent. The people that built the house ran a special vent in between the studs and then ran it another 12 feet or so to the roof. Unfortunately they screwed it up and put the roof vent in wrong and a bird made a nest in the pipe and damaged the vent. Now it does not close properly and it leaks water when it rains severely. I want to exhaust the dryer right through the wall to the outside but I have to go through the metal in wall vent and then through a very thin exterior semi rigid insulation and then through hardi plank siding. There is no exterior sheathing on this house ( Texas has some pretty lax code in this area), so I just need to go though the hardi so I can slide the new dryer vent all the way through. My issue is what would be the best hole saw for this project and what if any flashing should I put in once I have the hole made? I do not know why the builder didn't just vent it to the outside wall in the first place but I need to get this done soon as possible because I have noticed some small water stains on my laundry room wall and one time there was water on the floor under the dryer when I moved it out of the way. Any help would be appreciated.
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Old 10-09-17, 10:44 AM
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The "best" thing to do is to cut out the siding square, and mount a 7 1/4 x 7 1/4" square of Hardie trim to the wall, cut the hole in that, and mount your dryer vent to a flat surface, and caulk the siding to the edges of the Hardie trim. With no sheathing, you would need to install a piece of 2x12 blocking between the studs so that you can nail both the block and the cut ends of the siding.

If you just drill through the lap siding in an arbitrary location, your dryer vent may land over 2 different pieces of siding, which is a real crappy way of doing it.

You can cut and drill the siding just like wood, it will just dull your blade pretty fast. When I can, I use a Hardie jigsaw blade to cut holes... drill a small hole, then use the jigsaw. You may have a hard time finding that blade, depending on where you shop.
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