I have an old stick-built 10' x 10'shed with a concrete slab. The bones are in good shape, but the exterior trim, door, siding and potentially window need to go. This is a new project for me, and with the possible exception of hanging the door, doesn't require as much skill as it does a best practice knowledge base. I have some inital questions and am sure I'll have more.

First, I'd like to pull off the old rotten siding, and replace with Hardie Plank. The current siding is nailed directly to the studs, but the studs are not braced. There is no sheathing or moisture barrier. The shed is only 10'x10' with maximum height of 10'.

Should I brace it or add sheathing, eg. 7/16" OSB, before siding with Hardie Plank? How about adding a moisture barrier on a shed?

Looks like a lot of folks prefer the power snips instead of using a circular saw. The dust is pretty significant, apparently with the circular saw even using the recommended dust reducing blade. I saw some snips in a video that were an attachment to a drill. Opinions?

I know I need the HZ5 plank based on my climate. I'm fairly sure I want the pre-primed siding, but the pre-painted sounds like it might be worth it because of the process they use that increases longevity of the paint. Opinions? One issue is my project is small, so acquiring what I want in small quantity might make it expensive. Looks like pre-painted runs about $15 each for the 12' x 8.25 if I'm buying 240 of them, but I only need about 60, so I expect to be charged a premium.

Are Gecko Gauges worth the money for a project this small?

Thanks.

The way you handle moisture varies with the climate aka area you are in.
Here we use a breathable membrane aka house wrap and yes I'd use a plywood (not OSB) sheathing 5/8" is sufficient.
As far as the dust they I'd use one of those tile saws with the water feed although a 10x10 shed shouldn't be much of an issue to just deal with the dust, just use a blade made for it > circular or chop saw.
YMMV

I had a siding job done last year. I was thinking about Hardi but the supplier and contractor showed me an engineered wood siding called LP Smartside.

The contractor did the house and I did the detached double garage. I’m very satisfied and it installed easily.

its just a shed...you can put the hardi plank right on the studs.

or you could throw some plywood, wrap it in fabric and then hardiplank it and it wont matter where the nails hit.

remember to caulk the ends and then to paint it.

Sheathing is needed for shear strength. 1/2” OSB is fine as long as you use a moisture barrier. I would replace the window and do a proper moisture wrap on the window jamb. I would hit the studs with the fasteners. Might as well do it right.

I have a Hardi Plank snipper I could send you to use. I would use 1/2" plywood under it, house wrap is an option on a unheated building, but in my book, not necessary.

I rebuilt my garage and did osb sheathing, tyvek wrap, corrugated plastic for rainscreen, and LP Smartside. I'd rather cut 4x8 panels to fit rather trim than a bunch of lap siding. The thinner SmartSide goes over sheathing, the thicker stuff can stand alone. I think it's fine for a shed. The big deal is to prime all cut edges.

I used the primed Hardie Plank on several houses we renovated. Hardie holds paint really well in my experience. I wouldn’t think the prepainted stuff would be necessary from a longevity standpoint.

Good info guys, I appreciate it, even the differing opinions. I think the wife is stuck on the "charm" of the siding, plus it looks like the Gecko Gauges make it pretty easy. She likes to dress it up with window boxes and stuff.

The Hardie pre-painted siding goes through a process where they heat the siding and apply the paint. Apparently that improves longevity to as much as 20 years. If it's 15% more, it might be worth it. We've had Hardie on part of the house for more than 15 years, and I'm very impressed with it.

Thanks for the offer of the snipper, wreckdiver. Not sure what I'm going to do yet, but tell me how you fell about using the snipper. I'm curious about how clean the edges are and how hard it might be to create a really straight edge? What about when you need to rip a plank?

There is a hardie board saw blade available for your circular saw. That what I used. I also have an old asbestos shingle cutter that worked well.
I would snap chalk lines and hang the siding.
Leave an 1/8" gap near the corners, doors and windows for caulk and fill each row as you put them up. Dont wait till the end.
Post some pics when you have a chance.

I had a shed built in Jan.2011 using Hardi Board with a metal roof. Painted it myself and it still looks good. Only maintenance is occasional pressure washing to clean it.

We have prepainted hardi-plank siding on two houses in Northern Michigan. The one house is 13 years old and the other 10 years old. The walls on each that get exposure to the sun need to be painted. The pre-paint started peeling last year. Also, the planks shrank a lot. There are 1/2" gaps where planks were butted and the planks have cracked where they we notched for windows and such. Again, this is only happening where the sun is beating on them.

^^^that’s interesting. I live about 100 miles from the border with Mexico and have hardie siding (not the prepainted type) on the west side of my house, where it really does get beat on by the afternoon sun. Wood on that side has to be repainted every 3 years, the hardie siding hasn’t really needed it since we put it up over 10 years ago. No shrinking or cracks, either. Except where the inept chowderhead yard man (me) has hit it with the mower and broken a chunk out of the edge of it.

As a builder local to you let me interject my 35 years of opinions!

You definitely don't need 5/8" plywood that is just ridiculous..
I would recommend 7/16" OSB for bracing. It's relatively cheap ( although currently prices for all building materials are through he roof!). As far as a vapor barrier that depends on if your planning on conditioning the interior. If not you don't need a vapor barrier as both side are in equilibrium.

Now for the big one...as far as Hardi Plank is concerned I would have you consider Smart Lap as a better choice. It is an OSB product that has superior binding properties and will last longer. I have personally taken a piece of Hardi Plank and Smart Lap and placed them both in a 5 gallon bucket of water for over a month and suffice to say the Smart Lap was in almost perfect shape while the Hardi Plank had swollen considerably. We exclusively use Smart Lap now for our lap siding. The added benifit is that you can easily cut it with a regular saw. You can look on our website in my signature line to see some of the houses we build.

As far as pre-painted versus primed I will recommend primed all day long. The reason being is that you will inevitably have to do some touch up and even if you buy the touch-up paint from Hardi your application of it won't match the commercial application done in the factory and you will be able to see it if you look carefully. You should also be able to paint it much cheaper than buying the pre-painted product. Even paining it yourself if you use a good quality paint it will last 10 years or more, particularly if it is a lighter color. Darker shades will require more frequent applications.

Regardless of which product you use be sure to watch the companies videos about how to properly install it. Proper spacing and flashing will go a long way to keeping your project looking great for years to come.

Let me know if you have any other questions.

Thanks for the input smsig. Food for thought.

Priced the pre-painted Hardie today, and almost $17 vs. $9 for the pre-primed. So, no to the pre-painted planks.

By Smart Lap I assume you mean LP SmartSide? I love the idea of no special tools, but it's more expensive per board foot than the Hardie. The 16' length, if that's all it comes in, is awkward for my small project. Hardie has also been great around here to deter the carpenter bees, but worth considering.