Depends on how thick the strapping is.

Ok, so if our OSB is 7/16 (I think) how thick would the strapping need to be?

Hard to know without your window, trim and labor workmanship details. Use ring shank fasteners, 3/8-3/4" battens and skip the blocking as long as you arent in a high wind design area like on the coast or top of the mtn.

Thanks!

kind of depends if hes face nailing, or blind nailing. face nailing will only net you the thickness of the materials behind the cladding. Blind nailing (at an angle) will give you more penetration, because of the angle of the nail thru the substrate.

My experience is that it takes less fastening strength to hold the cladding in place with a rain screen, just because the siding does not move nearly as much.

You may be confusing two very different issues: 1) structural rigidity using continuous solid blocking; 2) a water drainage path for the exterior siding or cladding.

If you are in a seismic or high wind zone, then you will certainly need continuous solid blocking in vertical, horizontal and roof planes.

What does your local building code and building official say?

Good luck with your project.

I think Kiwigem is referring to what some here say is necessary behind the horizontal battens and sheathing to get "proper" fastener depth. I say worry about other things.

The success of nailing vertical siding to strapping and sheathing instead of to the frame of the house will dependent not only on the thickness and kind of strapping but on (1) the width of the vertical board siding, (2) the type of joint (shiplap, T&G, batten, etc), (3) the moisture content of the siding (KD preferred), (4) the nail holding capacity of the sheathing (5/8" plywood preferred) and the kind of nails used.

In order to allow good drainage and simplify the detailing at the windows and doors the strapping should be thin and very porous rather than thick and solid.

Hi Kiwigem, just wanted to say it is great that you are paying such close attention to this and also that you have my sympathy. I am glad the pros here are weighing in.

We also have vertical siding (Hardie panel simulated board and batten). Despite detailed construction plans, when it came down to it, our architect, builder, framer and "green consultant" had to huddle to re-puzzle out the wall system. We also had some kind of horizontal strapping with standoffs and because we used advanced framing there was some blocking(?) added. As a result our exterior insulation is not continuous, which was a mild disappointment. [note: I very well could be using terms incorrectly, this is just from memory] If there ever is a next house we are using horizontal lap siding or shingles!

Good luck.

Thanks Oaktown. In the area of exterior cladding, I think designers get carried away with blocking for the most part. As you say, continuous insulation is important which is why exterior, insulative sheathing is required in many climates by the the 2012 building codes. Insulative sheathing is uninterrupted R value and typically much more meaningful than advanced framing details.

Thank you all for weighing in. Yes, Brian you are correct; the question was about fastener depth.
Oaktown: Thank you for that thought! The continuous insulation hadn't even occurred to me. What it looks as though everyone agreed upon after our "huddle and re-puzzle" is normal 1X3 strapping set on the diagonal with no horizontal blocking. Siding will be blind nailed so no visible fasteners. Whew. My crew will be glad to be finished with all these ruminations, as will I!
I am so grateful for everyone's input, I can't even tell you.

3/4" strapping will require some additional details/flashings at the windows and door openings. Sorry, just had to throw that in from an experience standpoint. That is why I moved away from 3/4.

The details kill you...

Famous last words, but... That's my architect's problem :-)

Diagonal strapping has the unfortunate disadvantage of directing water to window and door openings instead of downward to weeps. The advantage of gravity for drainage should be disrupted as little as possible.

Again, rainscreens and the idea of air gaps behind the siding or cladding is to improve the physics of drainage and drying for the structural sheathing, siding and finishes. There should not be very much water flowing behind the siding. If there is, there are bigger flashing problems going on that need improvement.

Reno8 as always, you raise an excellent point and now that you mention it, it seems so obvious! I will bring it up with our architect.

Brian, I get your overarching point, but not sure if I am clear on your specific point; do you mean there should be so little water that it won't hurt the horizontal strapping, that if the strapping is on the diagonal it won't hurt the windows, or both? Thanks.

A simple space/gap in the diagonal strapping prior to the opening should stop any water from getting to the weak point in the system . Like 1 foot away..

Should there ever be a breach/ defective area in the cladding, it will be much harder to diagnose where the actual problem is, because it may exacerbate itself a considerable distance away from the breach.

Now, I'm not saying don't do this, or it's a bad idea, just throwing a "what if" out there.

Okay okay! Horizontal strapping it is :-) I have no allegiance to the diagonal; was suggested by my architect, but your points make a lot of sense.

Good luck with your project. :)

Both! There should not be enough water running behind siding or cladding to hurt horizontal or diagonal strapping/battens. As for diagonals redirecting water, window and other horizontal interruptions should still have cap/z-flashing so it shouldnt matter there and the strapping should have gaps where they run into windows, trim or other vertical transitions.

Yes, a vertical batten/strapping system is preferable but I would argue for reasons of ventilation as much or more than than bulk water risk. So with this thinking, a diagonal batten system should allow more ventilation.

Nitpicky details are what usually prevent people from committing to a rainscreen and that is unfortunate. Its the airspace that matters. Diagonal and horizontal battens are typically much better than no rainscreen or airspace at all.

This post was edited by Brian_Knight on Wed, Oct 15, 14 at 14:38