More Building Matters
I recently left the company I’d been working for in favor of a loose partnership with Brent, a fellow I’ve worked with on and off for the past 15 years. We went to look at a remodeling job last week, one that will keep us busy for a few months. There is no formula with remodeling, and every job is, as my old boss says, a prototype. Trying to do as green a job as possible adds another layer of difficulty in both design and execution.
Building forensics
The original structure in this case is an English-style barn, about 30 x 20 with a hay loft under the roof and the main doors on the side. The house it’s associated with was built in 1795, and the barn is probably the same vintage. It’s one of the older farmsteads in the Norman-Rockwell-ish town I live in, and although the property has been gentrified for probably close to a century, the barn is still rough around the edges. The timber frame is hand-hewn, but square-rule, that is, the joints are laid out with a framing square instead of being individually scribe-fit, one indication that a timber-frame isn’t much older than the late 18th century, which reinforces my guess at its age. A 20th century lean-to addition extends the back side by another 10 feet.
Like a lot of old barns, empty mortises and layers of newer framing testify to how much this one’s been hacked and modified and cobbled onto as its role in people’s lives evolved. It’s currently used as a garage, and its future use is going to be as a nicer garage with a man-cave in the loft. Based on my experience, it’s not surprising that the bits we’re going to have to demo and rebuild are the…
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7 Comments
Andy, great story--as nice as it is to see a perfectly preserved original timber frame, it seems much more common from what I've seen for them to be hacked up or made from at least some salvaged material. And thanks for the credit. I agree that BS + Beer has a lot of potential. New groups are popping up all over the US. If anyone wants a list of tips on how to start their own group, just message me.
To be clear, I had nothing to do with creating the discussion group concept--that was all Dan Kolbert and Steve Konstantino. I wrote about it here ten years ago: https://www.greenbuildingadvisor.com/article/steves-garage. After I moved to a different part of Maine I started a similar group and the silly name BS + Beer popped into my head. Anyone is welcome to use it, preferably for more building science discussion groups!
A question about your article--what makes it an English-style barn? I thought English-style barns had the main doors on the eave side, but I'm not sure if that's a requirement.
Good question, Michael. The barn in the photo is for illustration only. That's what I call a Yankee style barn, which is an English barn with the door on the gable end. Cool barn though, outside of Millbrook, NY. You're right about English barns having the door on the side, and that's what the project I was writing about has. I didn't want to publish a photo of the project barn to protect the owner's privacy.
Andy, thanks, great story, hope you will keep us informed. I appreciate you discuss the gradations of right and wrong in this business.
You link to an article by Martin H at https://www.greenbuildingadvisor.com/article/insulating-walls-in-an-old-house-with-no-sheathing that advises an air gap between insulation and the interior side of antique wood siding, and you seem to be substituting a grooved (DuPont) or very bumpy (Obdyke) rainscreen instead of an air gap - do I have that right?
I wonder if you can say more about why any gap greater than the thickness of ordinary Tyvek is important. Martin's article basically used the analogy that the interior gap in a retrofit is like the exterior gap in a new build that's between siding and sheathing. But I don't get the analogy to the interior. Partly because I have an idea the exterior gap is always part of a drainage plane with an exit for the water at the bottom.
Also, you wrote "It’s looking like the possibilities are Tyvek StuccoWrap or Benjamin Opdyke Slicker outside of tarpaper. The StuccoWrap would leave a little more space for insulation, but the Slicker would make a bigger airspace." I got confused at the mention of tarpaper. In this case do you mean `forgetting about tarpaper because it's not going to solve anything' or do you mean something else? Martin's article did have a detail with asphalt felt + closed cell (that one doesn't seem to let the siding dry to the inside).
David, what I'm thinking about doing is reverse-engineering a rain-screen. I didn't delve into all the details because that wasn't really the scope of the piece. And I'm also hoping someone who reads this has a better idea! So, the drainage plane is either the Tyvek or the tarpaper interior to the Opdyke. The trouble is, there's really nowhere good to drain that. The plan is to slip some rigid flashing as far in between the sill and the siding as possible, but without being able to cut the siding nails, this is a sort of hail Mary. Which points to why I want the Opdyke rainscreen - It produces a larger air gap, which I think will aid drying.
Andy,
Of all the attributes of a rain-screen - A capillary break, redistribution of moisture, a drainage path, a ventilated gap - the one I'm not sure ever gets used as designed is the drainage path. Does water really find it's way down the cavity in amounts sufficient to need a dedicated exit at the bottom? Maybe in extremely rare cases, but designing an interior rain-screen as Martin suggests, even without the drainage path, would still have all the rest of the useful attributes a rain-screen provides.
I like how you think.
Great piece, Andy. Mike, as usual, is being too modest but that's his problem. It's incredibly exciting to see how his name has led to an explosion of groups.
It's great reading about your struggles with the issues - it's critical to what we're all trying to do. I always say that developing an interest in building science is a good way to never sleep again. Add in the environmental concerns and we're really in for restless nights!
And on the technical side - I wonder if you've thought through air sealing enough. Maybe that's a fool's errand on this project.
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