View Full Version : James Hardie Cement Fiber - Lap Siding

Michael Schumacher
09-18-2008, 11:25 PM
I'm looking at replacing my siding on the house and looking at James Hardie Cement Fiber. I've been looking online for information/tips about installation and I've looked at their website too
I have a few questions for those that have installed it:

1) For the butt joints in the middle of the siding, not coming up to a trim piece, how should that be handled? I'm wondering if it would best to caulk it (along with the tar paper behind it). What about priming the edges as I install it?

2) Painting - the price of the ColorCast is way too much compared to the primed. I've read online that it holds paint very well, but seems like most are doing two coats of paint. I'm just wondering how much coverage a gallon of paint will do?

3) Trim pieces - I've been priced for a trim piece that is 10' long by 4" I think - about $10.90 per piece. What other options is there that would have the same maintenance as the cement fiber.

4) My current house has that wonderful fiber board (at least that is what I call it) where if it starts getting moister behind it, it starts expanding, which I'll be removing. Under it is 3/4" foam board. I'm wondering what would be the best thing to do - a) Put up Tyvak wrap; b) Use 30# felt paper; c) use 15# felt paper.

If you have any other tips, please share them.

Thanks, Michael

Ken Fitzgerald
09-18-2008, 11:35 PM

When I had my new shop built, it was just an empty unpainted shell. It has James Hardy Cementous siding. The builder left about an 1/8" gap between ends. I caulked them and then painted it. The siding was pre-primed. At the corner the builder placed a brick molding of sorts. It's the type of trim You generally see around doors and windows in brick homes. The siding was butted against it with a 1/8" gap. Again, I just caulked the joint and painted it.

Jim O'Dell
09-19-2008, 7:17 AM
During the first phases of my shop rehab, I stripped the 1/4" ply sheathing off of the shop, made the structural repairs and changes and installed the primed Hardi Board. I used the 1 X 4 for the corners and it has worked out fine. Follow the installation instructions on the Hardi website. They are very specific on how it is to be installed for warranty purposes. I used the 12" wide planks and had to face nail (I used screws) the bottom edge. The 5 or 6" doesn't have to be done that way. Not sure about the 8".
It holds paint very well. I think I used 2 1/2 gallons on my shop. It's 20 X 24, with a 10 X 14 porch I enclosed to be my assembly/finishing room. This also did the eaves, which were not Hardi Board.
Leave the gap between boards for expansion/contraction issues. I used an exterior paintable caulk. Fill the hole proud of the material and run a putty knife down the seam to skim off the excess. I found that if you do this slow enough, the knife follows the texture of the Hardi Board and transmits that to the caulk, and the seam virtually dissappears when painted. I had to do 2 applications of the caulk as it shrinks pretty badly on the first thick application. Did the same thing with the holes from face nailing (screwing) and they also went away.
If you cut with a saw, be sure to wear a good breathing mask, as the dust if fine, and very dangerous. Jim.

Jim Becker
09-19-2008, 8:36 AM
We used the pre-finished product on our home as part of our addition project. When we compared the cost of that to the labor cost of having paint applied, there was significant savings. We also liked one of the available colors (Timberbark) and were fine with the 25 year finish warranty. If you are going to do the work yourself, there is a different dynamic, but you still have to weight the cost of a high quality coating (such as SW Duration with it's 50 year warranty) vs the cost of the pre-finished, too.

At the piece to piece seams, our installers had some backer flashing. Piece to piece seams were not caulked. Edges along the corner boards, etc, were caulked with a color matched product from Hardie.

As for the house wrap, there are several good products on the market, including those that add a small amount of additional insulation over what "standard" Tyvek offers while still allowing the structure to breath as it must. These are all preferable to any kind of building paper.

For low maintenance trim, you'll need to spend some money up front. Azak, for example, which also paints up very nicely with the Duration coating. Our trim work is Azak in areas where its additional durability would pay off and clear pine painted with SW Duration for the majority.

Matt Ocel
09-19-2008, 8:53 AM
1) For butt joints I cut pieces of house wrap 6" wide and as tall as the siding.
2) I'm not a big fan of pre-finishing. To much touch-up after.
3) Trim pieces are all over the board. One tip I can give you is - I nail it using a 15g trim nailer. Smaller nail heads than the Hardi nails and the Hardi nails don't penatrate as good as a trim nail.
4) I'm a big fan of house wrap a bigger fan of Tyvek.

Also - for maximum performance of Hardi, follow "all" James Hardi recomandations for application. Especially clearances.

Matt Ocel
09-19-2008, 9:03 AM
One more tip.

Get a pair of these.


Greg Cole
09-19-2008, 9:12 AM
What Ken, Matt, Jim and Jim said....
I did my house with the Hardi Lap siding. Love it. I'd do it again in a heartbeart too. I used the matching Hardi trim and as Matt said installing that stuff is a bit of a PITA, as it breaks pretty easily. I think I broke 2-3 pieces just mioving them around, nevermind firing nails in it.
I used the pre-primed stuff, 1/8" gaps everywhere as necessary and all filled with caulk. I also applied an additional coat of primer as the preprimed material is primed more to protect the material in storage, Hardi also recommends priming before painting. The fiber cement eats up primer and paint the first go round, but it paints very well. Hardi recommends back rolling after spraying, so I just simply painted with a brush.
My home is @ 1400 sq. feet, I used @ 8 gallons of primer and about the same for paint. I'll say it was worth my time to prime and paint versus the upcharge for prefinished material.
And, definately go with the Tyvek house wrap.


Michael Lutz
09-19-2008, 1:58 PM
I did mine differently due to issues with my house, due to lack of overhangs or eaves.

1) Just butted them together and caulked the joint. I painted the joint after and it is not very noticeable. I didn't leave much of a gap. I didn't use any special backing at the joint. I used PVC inside and outside corners and J channels around the windows. So I left gaps at the corners so they were not as visible. I paint all the cut ends of the siding before I put it up. Instead of running all the siding horizontal, we ran it on an angle parallel with the gable of the house, hence the need for extra protection at the corners of the wall.

2) I purchased the Hardie siding prepainted. They had a color we liked. Ours was factory applied, which was significantly less that the Cabot stain option. It was a Valspar paint which they were able to sell us at the local hardware store to mantch the color exactly. The cost increase only added about $1000 to the cost of the siding. It would cost much more to paint my house.

3) I used PVC azek board for areas which I had exposed where I wanted more protection or needed a wider reveal than the PVC J channels would provide. I used the azek board as freeze boards under the gutters and along the roof trim boards. It paints pretty well.

4) I had water damage in a few walls so I am removing most of the sheating down to the studs to suvey the damage. I used plywood sheathing, foam baord and then a layer of Tyvek wrap. My house originally had the tar paper which didn't appear to do much good to prvent water infiltration from destroying the walls. Around the windows I used bituminous window tape and aluminum flashing. At the corners I used a similar flashing method.

I used SS ring shank nails with a framing nailer. If you are going to cut the stuff with a saw blade, get a diamong blade for that purpose. A carbide blade won't last long.