I’m looking at doing my first project with HardiePlank Lap Siding and Trim on my house.  I’ve read the technical documentation and overall it looks like it pretty strait forward to install.  This project is a partial remodel of an American Foursquare in a historical district. I’m trying to match an existing trim details on the house as much as possible to avoid issues with the review board and I would like it blend as well as possible.

  • Existing door/window trim (aluminum) features a 45-degree cut between the top and side trims.  Does HardieTrim support being cut in such a fashion?
  • Existing window trim features a 2” thick sill, but it appears your max thickness is 1”.  Any suggestions to achieve this thickness with the Hardie product or should I plan to modify the style with a 1" sill?
  • Unrelated to the trim, a side of the house that is getting Hardie Plank has a deck fence/railing next to the wall.  If I understand the technical materials, this post needs to be at least 2” from the material to prevent drying issues?

Thanks, Mike

Existing House Window Detail

  • 1
    About the sill... are you replacing the windows, because the windows generally sit upon the sill (as seen in your photo of the existing window)? If you are replacing the windows during this remodel, the technical specs. for the new window(s) will detail sill configuration/requirements. I would not want my windows sitting on a sill that was only 1" thick. Also. I see nothing in the technical instructions requiring a 2" gap from siding to deck post, where are you seeing that? Aug 26, 2020 at 0:24
  • As long as you have the right saw blade (cement ones are expensive) then I don't see why there would be a problem with cutting it at any angle. Cutting at a 45 is no different than cutting at a 90-degree angle straight through.
    – TylerH
    Aug 26, 2020 at 13:54
  • Although PVC moves a lot in temperate areas, shorter pieces may do well here. PVC can be glued up and shaped to match your existing profiles. Mill parts so they do not simply apply to the face of existing structures, set/shape so a physical barrier is created so the weather does not get the chance to infiltrate, not by caulk only, which degrades and needs to be maintained.
    – Jack
    Aug 26, 2020 at 14:53
  • I agree with Tylerh it should cut fine, I have used hardie trim and was not impressed. I love the lap siding and sheets but that trim I have had nothing but problems with. .I usually go with cedar 5/4” for trim usually works much better I quit trying to use their trim 20 years ago so possibly it is better now but it was quite fragile and cracked even when pre drilling after 2 times trying to use it I never again purchased it.
    – Ed Beal
    Aug 26, 2020 at 15:37


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