Rainscreen with Vertical Cedar Siding
vanderlin
| Posted in Green Building Techniques on
We are about to start putting up siding for our house and have questions about a rainscreen. There are many posts about this topic but was hoping to get advice for our situation.
Wall assembly:
closed cell spray foam + 2×6 framing + zipr 1.5″
Building in Northern New Hampshire.
We are putting up unfinished vertical cedar siding. (we like the silvered look)
We are looking for a more affordable approach to building a 1×3 lattice rain screen. We had a plan to go just horizontal only but worry about water pooling. Looking for advice.
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Replies
What style of vertical siding are you planning - board and batten, plain butted boards, shiplap, or...? Will you be installing it green or dry?
Are your windows already installed and if so, are they installed right on the sheathing?
The siding is a "rustic channel shiplap" 1x6, they are dried boards. The windows are not installed yet, the plan is to buck the windows out the 3/4" with strapping (liquid flash and tape) to meet the siding.
So I put up 1x6 shiplap green hemlock on my garage. I used 1/2" ply furring over 1/2" ply sheathing. The furring strips were ripped at an angle so any water is pushed out to the siding. I used ringshank framing nails fasten the siding. The shiplap joints gapped to about 1/8" after drying, creating drying and ventilation paths. I don't think it's as good for ventilation as a large gap like you get with a lattice but it's better than nothing. It's only been up a year so I can't really give you a review. Since your cedar is dry and I'm assuming will be installed tight, this won't work, but you could cut kerfs into your strapping or make the furring out of T1-11.
Before using Coravent, or even 1/2" ply strapping, I would consider the fastener hold in the ZIP-R and whether it's enough to hold the wood tight, unless you've installed blocking between studs. (I don't know if just OSB enough)
If you're planning on spacing out your windows anyways I would just do the full double layer lattice. You could save material by not using full length strapping for the first layer, though that might take longer.
If you can afford spray foam insulation, Zip-R sheathing and cedar board siding, surely you can afford to invest in a proper rain screen. I've used diagonal strapping to create a vented space that drains in one layer, but I find horizontal battens to be easier to work with. There are batten products available that will drain (https://www.greenbuildingadvisor.com/article/understanding-rainscreens) or you could use a drainable WRB such as B.Obdyke's Hydrogap under the strapping.
I have a slightly different wall assembly: cellulose/ply/WRB/1” rockwool/furring lattice/vertical cedar siding.
In this case can the siding be attached directly to the horizontal furring if it is only attached to the vertical furring and not the sheathing, as I would like to minimize WRB penetrations.