Do we need to paint the bottom of the rainscreen battens
idahobuild
| Posted in General Questions on
hey all,
We have a 3/4″ rain screen going over 2″ of rigid Polyiso. Where the battens are low, and closer to the bottom/rain, do we need to paint or treat them?
We live in a fairly dry, high desert area in Idaho. I am leaning toward no, as they should have time to dry out between rain events.
Also, any reason to move from 1×4-8 fir strips ($3.34 ea) to use Common lumber ($6.47) for battens? At 1,900 linear feet of batten it makes quite a difference.
Detail attached.
Thanks
Walt
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Replies
Walt,
They should dry out between rain events, and are pretty well protected by (usually) ending about an inch above the siding, with a screen below.
If you are particularly worried about it, another option is to run an L flashing 3/4" below the siding.
Ideally you want a vent at both the top and bottom of the rainscreen to allow for air movement. Cor-a-vent SV series vent strips are often a really good fit here, or use perforated channel or even window screen wrapped over the bottom edge of the furring strips. I'd avoid aluminum screen here though as it tends to degrade over time. Fiberglass is better, but more prone to critters chewing through it. My favorite material is stainless steel screen, but it's the most expensive option.
Edit: somehow I read that as asking about venting, but your title was about painting. I agree with Malcolm that they'd probably be OK in a dry climate, but I'd personally give the last few inches or so a coat of Coppercoat, or at least exterior paint, to help avoid any issues in the future.
Bill
Hey Walt,
Check out FM3 from AlBuild Systems. FM3 is a steel hat channel with corrugated flanges that allows for efficient drainage & ventilation behind your siding. Can be installed horizontally without the cost & hassle of double-strapping. Very labor-friendly product, and much less product waste than wood furring.
https://albuildsystems.com/fm3-vhv/
Amelia
Amelia,
It looks like an interesting product, but GBA's policies don't allow for the use of the site as a forum to advertise products or services.
"Also, any reason to move from 1×4-8 fir strips ($3.34 ea) to use Common lumber ($6.47) for battens? At 1,900 linear feet of batten it makes quite a difference. "
Not sure if you're talking about 2x4 as common lumber, but I wouldn't bulk up like that. Sure it's a little stronger for siding attachment, but a well secured 1x4 should be adequate for almost all siding and 3/4" is plenty of air gap for the rain screen.
If you're talking about upgrading the lumber quality for the 1x4, then I don't think that's worth it either as even if you're getting a straighter board it's not going to make much difference in end quality here. I've even built a rainscreen with ripped down 1/2" ply that we had on hand to save costs.
As others have already noted, painting the ends of your battens isn't needed as the Cor a vent specced in the drawing will prevent them from getting wet by any rain splash back.