some options for trim under a porch

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LMHmedchem

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I guess that this is the correct forum for this question, someone let me know if it is not.

I have mostly finished rebuilding the structure of the porch after significant termite damage. There is a new rim-joist supported by 5 posts and concrete footers. The old trim was an 8" frame of wood with lattice. The wood was wrapped with aluminum flashing.

For the replacement I was going to just use PVC boards and paint it. I don't want to use anything that will be susceptible to insect damage. Looking at the crazy prices, it will be almost $500 for the PVC trim boards, plus the cost of paint.

Today I looked at Hardie fiber cement trim boards. These would cost only about 1/3 of the cost of PVC and come in the color I want. I have never used this product before so I thought I should ask some questions before going that route.

How easy is this product to work with? Does it cut like wood with the correct blade?
How do you manage tasks like caulking and filling fastener holes and any seams?
What kind of fasteners are used?
Is there generally a color matched touch up paint available?
Does it make more sense to use the primed version instead of a color and paint it?

If folks here think that this is a bad idea to try then I could go with pine boards and soak them in copper naphthenate, but I am not sure that I could get the surface to look good after painting. I could go with PVC but that would be very expensive.

Thanks for the help,

LMHmedchem
 

Sparky617

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Can you post a picture? Hardi cuts with woodworking blades. It is dusty and tough on the blades though. A good facemask is recommended. Hardi is attached with galvanized siding nails. I haven't worked with the prepainted stuff, I suspect they have color matched paint to go with it to handle cuts and caulk joints. If not, the paint department should be able to mix up a batch in the right sheen. For anything near grade I would not use standard pine. I prime all 4 sides and the cuts on any exterior pine or fir trim and caulk the joints as I'm installing it.
 

LMHmedchem

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Can you post a picture?
Here is a picture of the right side. The distance from the steps to the outside of the corner post is 135" so a bit less than 12'.

porch_framing_right_01.jpg

The left side is the same only not as long so there are only two posts. I have not yet installed the post caps as I had to fabricate those and they still need to be painted. There are 12" concrete tubes under each post with a 10" deep 20" x 20" square footer at the bottom. When it gets warm again, I will cut out the old concrete on the inside an pour a new pad that is 18" wide and 3" deep. It will stick out about 4" in front of the posts and fill up to right under the light framing that I added to support the bottom trim. The new pad will cover the tops of the concrete tubes by 1.5"-2". Normally I would have poured this before putting on the trim but I ran out of time and it's too cold now. What is there above will have to be dug out some for the new pad. There is also cross bracing to add but I will do that after the trim since it will be harder to put the lattice in with the braces installed.

There will be a 2" section of brick mold at the top, in part to seal the gap between the siding and the rim joist. On top under the brick mold, there will be a 0.75" x 5.5" trim board that runs the full length across. There will be a 0.75" x 7.25" board across the bottom that is flush with the bottom of the light framing. This will stick up 1" above the light framing to provide a stop for the lattice. There will be 0.75" x 7.25" vertical boards at each post to connect the trim across the top and bottom. I have PVC lattice to fill in the center of each rectangle. The end is a little different as it has a door.

My question at this point is what material to use for the boards. I have confidence that I can make pine, pressure treated, or PVC look nice because I have used it before. I am not at all sure about the fiber cement board.

Hardi cuts with woodworking blades. It is dusty and tough on the blades though.
I was under the impression that you needed a PCD blade or carbide blade to cut fiber board. Can you cut it with a normal wood blade?

Hardi is attached with galvanized siding nails.

Siding nalis tend to have very large heads. Can they be counter sunk into the material? If not, it's hard to imagine that they won't show rather badly.

I suppose I would opt for the primed boards instead of the colored as I think it unlikely that I wouldn't end up painting it anyway, or at least some of it.

LMHmedchem
 
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Sparky617

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You don't want to countersink the nails. The heads aren't huge but they are visible. If you counter sink them you'd need to caulk them, even with caulking they wouldn't be invisible.

Most wood cutting blades are carbide tipped and the only kind I buy.

Siding Nails
 
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