Podcast Episode 166: Venting a Barndominium, Sealing Exterior End Grain, and Flashing Details for a Metal Roof

Follow the Fine Homebuilding Podcast on your favorite app. Subscribe now and don’t miss an episode: Patrick and Matt kick off the podcast by grilling Rob about his messy metal shop–but they all agree that (most) craftspeople need to have a ready supply of scrap materials at hand to feed their creative projects. Then it’s on to an assortment of...

Follow the Fine Homebuilding Podcast on your favorite app. Subscribe now and don’t miss an episode:

Patrick and Matt kick off the podcast by grilling Rob about his messy metal shop–but they all agree that (most) craftspeople need to have a ready supply of scrap materials at hand to feed their creative projects. Then it’s on to an assortment of listeners’ emails, with questions about ventilation requirements for a metal-clad, slab-on-grade home; the ideal product for protecting end grain on cedar and hemlock that will be exposed to the elements; and options for keeping water out of the gap between a chimney and a metal roof.

Editors’ updates:

Patrick and Matt have nothing new to report, but Rob shares some photos of a blacksmithing project he’s working on in his barn workshop. Of course, the guys spend more time talking about Rob’s cluttered shop than they do about metalwork.

Rob's metal shop
Rob's metal shop

Related links:

News: Lowes employee attacks customer

Think twice before arguing with box-store employees. Patrick stumbled upon a news story about a store associate who lashed out when he was called out about his lack of knowledge about types of tile grout.

Question 1: What should provide the make-up air in a well-insulated barndominium?

Joseph writes: Hello, Enjoy the podcast. Thanks! I’m currently working on what’s called around here a barndominium (basically an apartment built inside the shell of a metal building). slab-on-grade foundation. Entire building envelope has 2 inches of continuous closed cell foam sprayed on the backside of the metal. See pics. Only two exterior doors and 5 windows, Mitsubishi mini splits, Panasonic ERV.

Haven’t done a blower door test but can’t imagine a tighter house.

My question: When the owner turns on the stove exhaust or bathroom exhaust what should provide the make-up air?

Joeseph's barndominium
Joeseph's barndominium

Question 2: At what point do I need to consider an HRV or ERV when renovating an old home?

Matt writes: Hey, guys. Love the show and the magazine. I’ve learned so much from your content and have done a ton of work on my house as a result.

My question is: as an old house is renovated and becomes tighter, at what point should external ventilation (HRV/ERV) be added?

No clue how my 1967 house would perform on a blower door test, but I have air sealed a decent amount (attic, rim joist, downstairs renovation). Wondering at what point I need to consider fresh air. Thanks!

Related link:

Question 3: What works best for sealing cuts in exterior untreated wood (like hemlock or cedar)?

Blake from Northern Vermont writes: Hey all, I’d like to hear your opinions on products to seal end cuts. I bought anchor seal for the end cuts of a timber frame porch I built last summer on my place, I used it both on particularly vulnerable spots of the PT deck framing and the green hemlock posts. My father in law – a cabinet maker – insists that it’s useless since it’s wax based. He says it will eventually just evaporate. He prefers to soak the end cut in oil before installing.

I know there is a specific product for PT end cuts, but what do you guys think is best for untreated wood – like my green hemlock, or the cedar decking, or cedar siding? And what if primer isn’t an option because the wood will be stained with an oil-based stain and not painted? Just dunk it stain and move on with your day?

Thanks guys! Love the podcast!

Question 4: How would you handle the flashing where a metal roof meets a chimney?

Andrew writes: Hello, I am considering re-doing the roof on my 1946 bungalow with screw down metal roofing. Metal roofing in the town of Plymouth, NH is not out of place and I am in favor of it for a few reasons, ease of application, affordable compared to standing seam and longevity compared to shingles. We all know the 30 year warranty on asphalt shingles is pointless and is lucky to last 20 years. The mounds of old shingles at transfer stations are also an environmental concern for me. There is the concern of leaking on the metal roof with penetrations but most houses don’t have a problem and replacing the screws in the next few decades is still easier than a new roof. I also have a theory that if the roof is steep enough the water will want to run off rather than want to work its way under rubber washer.

Anyways, my only hesitation with the metal roof is the chimney flashing. I have watched numerous youtube videos and it seems there are many methods out there and most rely heavily on sealant at the seams between the roofing and the flashing. Snow could accumulate behind chimney and wind driven precipitation could find its way behind flashing. I had an idea to run ice and water shield vertically on the roof deck near the chimney to add a waterproof barrier but there will always be a seam near the chimney.

Similar to some of you, my pockets and ego cannot deal with hiring a specialist.

How would you handle the flashing?

#KeepCraftAlive trucker hat
Keep Craft Alive Trucker Hat

This episode of the podcast is brought to you by MiTek, ZipSystems, and Danner boots

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