Hanging and Staining Board-and-Batten Siding
Hello Green Builders. I’m just days away from hanging board and batten on my renovation and I’m looking for a final opinion on which hanging and staining methods to use.
First, the house: 1000 sq feet in central NH. Single story ranch. 2×4 studs. Closed cell spray foam insulation. 1/2″ plywood sheathing. tyvek.
Boards and battens: Pine. Milled by me on site. Dried 2 years. Averaging 10″ wide. Will be semi-transparent stained.
Now, pretty much everything I’ve read online says that strapping is needed when there is not either horizontal spans between the studs to nail off to OR suitable sheathing to hang from. However, in general people will tell you that strapping is needed for the boards to breath and for ventilation. I’ve also heard that the air space can serve as an additional layer of insulation (which is more compelling). The carpenter that did our structural work said strapping isn’t needed. I’m a DIY homeowner/renovator and my carpentry skills are relatively basic. Adding strapping seems to complicate the installation, especially around windows and doors – I’d prefer to keep things simple if there is little benefit to any added complexity. It also seems like if water did get in, the strapping is more likely to hold it against the house longer compared to a flush installation, IMHO.
Next, even here on GBA/FHB, I see mixed opinions on staining 6 sides vs just the exposed surfaces of the cladding. Staining 6 sides before hanging seems like a major operation in itself, not to mention needing all the boards pre-cut/ripped. I would only want to go through the trouble if it’s really important. Hopefully my wood is dry enough after two years that cupping and shrinking wouldn’t be an issue.
Pages that I’ve been referencing:
Thanks in advance!
Paul
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Replies
Nailing the 3/4" siding boards and battens onto 1/2" plywood seems like it would not secure the siding as tightly and positive as would be ideal.
Thanks. What's the risk though? I assume boards cupping or pulling away? What if I use more nails up front? I can always go back and screw any boards that pull away.
Paul,
Unfortunately, Board and Batten siding does a poor job keeping moisture out of walls, and so more than many other claddings benefits from both a rain-screen gap and being coated on all surfaces. Whether the added resiliency is worth the extra complication for you doing installation is a judgement call only you can make.
Thanks Malcom. You actually responded to the other question I linked to. In that discussion, Martin and Dana seemed to think water intrusion would be minimal.
Only using horizontal strapping seems like it would catch and hold any water that found its way in, where a flush installation would have a drainage channel between the boards. I can see that the best practice would be vertical strapping, then horizontal strapping, then B&B - I don't think that's realistic in my case though, given my carpentry skills and the time I have available.
So in my quest to understand the real risk of a flush installation, I'm thinking the following:
- the closed cell spray foam installation really shouldn't be letting much/any moisture through to the outside from inside the house
- moisture that does come from the inside should dry to the outside, as indicated in the other thread
- any significant water that comes from the outside would have to come around the battens and the boards to hit the tyvek or get behind the boards. it should be able to drain between boards (under battens) or wick to the outside
- the biggest concern: rain could come from the top of the boards and seep between the boards and tyvek. for a larger house, i could see this being a problem. I only have 5-6 inches between the tops of my windows and the soffit though - so it would take a wicked storm for water to enter there. under the windows I guess some water could get in. the upper part of the gable ends of the house WILL be installed over 1" strapping so rain hitting the outside will drip outside of the lower B&B
Regarding staining all sides, if the goal of the stain is to protect the wood by limiting water intrusion INTO the wood, it seems like it would actually inhibit drying to the outside if more sides are treated. In other words, if water did get behind the boards, and the boards are stained on the back, the water is more likely to be trapped. If that track of thinking is right, using the minimal amount of stain, only where needed, would be the better option. That would mean just the outside for aesthetics and to protect the most exposed surfaces. I can see the combination of a rain screen gap AND staining all sides being a bit more useful.
Kind of thinking "out loud" here. Let me know if I'm way off base.
Thanks!
Paul,
- To avoid the horizontal furring holding water you an either slope the tops, or use a propriety system like Cor-a-Vent.
- Something pretty big has to go wrong for the wall to have to actually drain bulk water down the cavity and out the bottom. Much more common is water wicking it's way along the edges of the battens and boards, leading to constant dampness, or moisture moving through the boards and wetting the backside. What stops these things causing rot is the ability of the boards to dry, and that is substantially increased by having a gap between the boards and the WRB behind.
- As to coating all sides of cladding, Dana Dorsett put it better than I could:
"Not only does back-priming prevent rot, it prevents bowing & cupping. All siding takes on seasonal moisture from sources as diverse as direct rain, wicking, and vapor diffusion through the wall assembly. But if it's painted on only one side both the wetting rates and drying rates differ between the exterior & interior faces, which creates mechanical stresses that result in warping/bowing/cupping/splitting.
But when you back-primer the siding the differences in drying & wetting rates are small, the goods stay pretty flat."
I just did something very similar a year ago. Board and batten with site milled cedar at a true 12" wide and some as long as 20'.
I agonized over these details forever. What I wound up with in the end was this...horizontal 1x3 blocking inside the house between the studs and 3/8" plywood strips vertically on the outside for the rainscreen gap. I did a semi transparent stain on all six sides (for the reasons Malcolm and Dana point out above) with a second coat on the outside. Stainless ring shank nails are holding it all up and so far there has been no visible cupping whatsoever after a very wet winter and dry summer.
Oh yeah, don't forget to cut some strips of window screen to fold over the spacers to keep the bugs out!
Thanks everyone. Here's what I've decided on:
- No strapping. It may not be the best option, but lots of people do it. I might put some drainage grooves in the boards under the windows, which is the only place I can see water getting in. Wish I had a molder!
- I got a weather sealer that I'll put on the backs of the boards a day before hanging. Cheaper than stain...
- Face of boards will have semi-transparent stain. Will probably stain after hanging boards, before the battens go up. Went for "Atlantic Blue" - decided to be daring. :)
- Sides of boards will be untreated
- Boards will be hung with 1 5/8" #8 stainless screws, spaced vertically every two feet, two screws 1/3 apart (more grip than nails, since our sheathing is 1/2")
- Battens will be pre-stained on 3 sides and sealed on backs
- Battens will be hung with 2 1/2" #8 trim head stainless screws
Thanks again.
Paul