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advice on siding

I am finishing up an addition and need help with the siding. We would like to use fiber cement board with clapboard style boards.

1. Is it a good idea to miter the corners? i saw a thread that advised against it for Dutch lap style. Does the same opinions (that the joint can/will open up) hold for clapboard? The look of a mitered joint seems more consistent with the rest our house (which is vertically hung cedar)

2. Do most feel the investment of shears (as opposed to a circular saw with a composite blade) is worth it? I am not sure I could cut at a 45 (for the miter corners) with a shear.

Thanks in advance for any help.


Re: advice on siding

I looked at some hardiboard sites and I did not see this done, nor did I see if anyone even asked the question. I think you can do it, but be aware that you are entering uncharted waters here. If you do, try going to some sites about hardi board, particularly sites with a factory connection that have a forum. Ask for advice, take plenty of pictures and if it works out, you might get featured by the James Hardie company.

Hardie board is a very stable siding, it doesn't absorb water and doesn't change dimension much due to normal temperatures. It is too thin to pin or nail the corners. I would recommend that you use some type of water proofing over the framing on the corners so that if a gap opens up, water will not get to the studs. Set the corners in a bed of caulk, the Hardie corp has some recommendations on which caulk to use.

When you attach the siding, you want the caulk to spooge out of the corner, then wipe off the excess before it dries. This is the recommendation for the butt joints so I would carry that over to the corner joints. BTW, you do not miter cut the butt joints like you would for wood lap siding.

Most fiber lap siding comes pre-primed so it is ready for top coat. My daughters house has a little cement fiber lap siding on it, mostly its brick, but I'm repainting it for her. It has a coat of "contractor paint" on it (5 years old) but we are using Velspar to repaint it and I have found that it really soaks up the first coat. I recommend that you use only a top quality paint like Behr or Velspar and buy plenty of it. BTW, the paint went a lot further on the second coat but the first coat was like trying to paint a sponge.

Re: advice on siding

with hardiplank NO! it wont perform correctly and the edges are too delicate.. but them into a corner board and caulk the joint. its the only way you can keep your warrenty intact

Re: advice on siding

I haven't tried what you are describing, but as Hardiplank is not tapered, it might be difficult to get the effect you want.

Re: advice on siding


The HB instructions call for a slip of tar paper to be placed at all joints. This is a really good idea as when the caulking fails, the tar paper will be there to shed the water. See figure 2

After seeing so many cracked caulked joints we know space the planks a smidge under 1/8" apart to get a decent bead of caulk in there. If the pieces are butted, the caulking will crack.

We also run the planks to the corner, then install the corner trim pieces which overlap the siding. Old school cause it works. I can't see how butting the planks and caulking that seam will work better.

Re: advice on siding

Does anyone have pictures as to what this looks like?? :confused:

Re: advice on siding

Perhaps Simpson makes a sheet metal corner for mitered look like the made for hardboard/masonite siding.

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