Hardi Planking

Has anyone out there had any experience with Hardi cement fiber planking for exterior siding,installing good or bad,what type of fastener is best,screws ,nails power nails. I would like to hear about your experiences.


one must use the pneumatic nailer designed for this application. I’ve tried hand driving a nail through it and it just shatters the siding. Keep in mind that a vapor barrier must be installed between the sheathing and the siding, whether it be tar paper or home wrap.

I had a Realtor a couple of years ago tell me, after I called out missing caulk on hardie siding,(deferred maintenance) that she had two other inspectors tell her that hardie did not need to be caulked, after I emailed her the installation instructions she would no longer talk to me. The Realtor called last month for an inspection for a very particular customer that requested a thorough inspection. go figure. Both of those inspectors are now out of business.:smiley:

I had plenty of that on my last home (2500sf home with 3 car detached garage). I thought it was pretty good stuff. The installers did a fair job, only had a few gaps between some of the planks, but other than that it was fine. Not too much waviness, just what was being telegraphed through from the framing in a couple of spots. Driving nails or screws through it is a little hard, kind of helps to drill a pilot hole first. You will need a masonry blade for cutting it. Well, at least the guys putting mine up used one. It is preprimed so painting is easy. No knots, splits, checks, or rot to worry about. I did get a little mildew on one area but it cleaned right up. Oh that is another good thing, you can power wash and not have to worry about shredding it.

The biggest problem down here is they putt it on with as few nails as possible and none at the studs so the bottoms flare up instead of laying flat. The lizards love it.



I install it with stainless steel ring shank gun nails, blind nailing and leave gaps that have to be caulked later.

Always cut downwind and wear a mask, definitely don’t want to breath in the silica dust.

Good Advice.


Ive installed a bunch of it. I used the shears to cut it most of the time. There is a special 7 1/4 inch blade for a skil saw for those times when the shears do not work. The shears have a short learning curve but will save you hours on top of hours cutting. I also highly recommend buying a set of Gecko gauges / clips to use when hanging the boards. It will save you time, aggrevation and hair. It allows you to work hands free and automatically sets the overlap of the boards perfect every time. If I can find the web URL I will post it so you can find both these items. I too used a nail gun. Find where the studs are and mark them out on the sheathing for a good finish. Like someone said, follow the instructions carefully and it is a superb product. Ive replaced most of the crappy Louisiana-Pacific lapboard siding on my own home and used it numerous times on others’ homes. My sister did her entire house in Hardiboard and it came out great. Paints like a dream, never rots, shrinks, bows, twists or any of the other problems normally associated with lapboard siding. Impervious to water, termites, hail, and green pine cones flying at 140 MPH in a hurricane.

Starting place for the right tools:

Actually earlier Hardi Plank instructions indicated that caulking at butt joints was optional. I have their year 2000 instructions still in PDF. (See excerpt below) So technically the two inspectors are correct on older applications when quoting the manufacturer.

Dents, chips and cracks can be filled with
a cementitious patching compound.
James Hardie products must be painted. For best results
install Hardiplank siding with our exclusive Prime Plus™
factory priming system and a 100% acrylic topcoat (s).

If our Prime Plus™ factory priming is not being used,
Hardie recommends the application of an alkali-resistent
primer along with 100% acrylic topcoat (s).
(For paint manufacturer’s paint
specifications, refer to JH
Technical Bulletin No. S-100.)
*Note: Please refer to paint
manufacturers’ specifications for
application rates.

A high quality, paintable caulk is recommended.
For best results use caulks that
comply with either ASTM C 834 or ASTM
C 920. Caulking should be applied in
accordance with caulking manufacturers
written instructions. (Leave 1/8” gap at trim
for caulk. Caulking at butt joints is optional.)

Hey Doug, You might find this interesting, it’s from the lasted issue of Coastal Contractor magazine.

The author is talking about installing a rain screen behind siding.

" For fiber-cement lap siding I use the same furring method as clapboards, yes I recommend back venting fiber cement, not so much for paint performance but to promote drainage and help the siding dry. Fiber-cement siding is a “reservoir” siding, just like wood, meaning it sucks up water and holds it for awhile and then releases it (dries out). The more opportunity you give fiber-cement to dry front and back, the better the wall will stay dry".

The furring method he talks about is ripping strips of 3/4 PT locating them over the studs and building out the windows and door ETC.

Thanks, I get Coastal Contractor too (a freebie subscription) but I rarely have time to read it anymore. Someone mailed me a sample of rain screen for just such an application. I have to admit, Ive never had any Hardi take up any water but now you got me curious. I am going conduct a few experiments with some scrap pieces I carry in the truck for show and tell with clients.

I found the sample; it is a yellow mesh sheeting that goes behind the siding;

Here is a sample shot. this channels any water down towards the bottom and keeps it away from the siding material. Bet is isn’t cheap.

Doug, The author did not like the Homeslicker because it’s hard to drive nails and he ends up with to many cracked “claps”

He goes on to say the PT furring strips are more cost effective.

PS, His responce is on page 5 under the letters section.

Thanks, I will look it up tomorrow or tonight. I actually have a day off for a change (so far). My wife may enlist me for something.

Doug, keep us posted, if you do a hardie plank job with or without a rain screen, please post some picture’s. I think it would be helpful and interesting

You can go to Hadie’s website for info on install & products it is: