Home & Garden

Podcast 364: Exposed Headers, Mansard Roofs, and Outdoor Rooms

Podcast 364: Exposed Headers, Mansard Roofs, and Outdoor Rooms

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Mark and Mike show us their exposed spiral ductwork. Wayne shares an article about bad stucco. Tamperjoe ask about durable wood choices for timber lintels. User-7829614 wants to know how to insulate a Mansard roof and walls. Dan wonders if his water-stained subfloor is okay for hardwood. Dack asks about combining indoor and outdoor spaces in a new build.

Editor Updates:

  • Rob’s new pedal tractor
  • Jeff’s garage water line for ice-maker
  • Kiley’s mystery insects

Listener Feedback 1:

basement ductsMark from North Easton, MA writes: I’m a big fan of the podcast and I enjoy listening while I’m working on one of my many home projects on the weekends. During last week’s show, you jokingly talked about the use of exposed spiral ductwork in a finished home. I thought I’d send along a photo of my recently completed new home where I featured exposed spiral ductwork in the finished basement. I’m an HVAC engineer by training so the design and installation of my new system was something I cared deeply about. I designed a variable speed and capacity air system with the distribution ductwork located in the basement. The system has 4 temperature control zones and 17 zone dampers and controlled from a Lennox icomfort multizone module. I also installed an HRV unit to provide fresh air to my aero-sealed building envelope. (1 ac/hr at 50pa) The system is super comfortable and extremely efficient. The spiral ductwork in the basement has an industrial feel and the branch ducts are neatly tucked between the floor joist.

The basement is insulated with 2 inches of closed-cell spray foam which extends to below the slab where there is 4 inches of insulation. The thermal break between the slab and exterior wall makes the basement a thermos and extremely energy efficient.

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Listener Feedback 2:

A-frame spiral ductMike Guertin writes: Hi Patrick, I think it was in podcast 358 where you briefly discussed using spiral duct and leaving it exposed.

When my HVAC guy came out to discuss installing central AC in my mother’s A frame house, I already had a plan: exposed spiral duct resting on the top of the rafter ties. There are no walls and no attic in the house and I figured it would be the least objectionable air delivery option. There was already a closet on the second floor where we could position the air handler.
Modern commercial design often embraces the mechanicals and makes them features. If mechanicals can be exposed it simplifies HVAC delivery. And as a side benefit, it makes service easier. Hopefully residential designers can convince home owners to expose more of what we often spend a lot of time and effort concealing (or jamming in a hot attic or unconditioned crawlspace).

Don’t ask about the odd arrangement of ugly ceiling fans – they are the remnants of my father’s attempt to circulate the warm air that hangs out in the peak of the house in winter to the lower floor. And ignore the I joist gang-planks—they’re my avenue to raise and lower the insulated skylight covers in the late spring and fall. Handling a 28 ft ladder inside the house was becoming a pain.

Listener Feedback 3:

Wayne writes:  Good morning Patrick, Attached is a good article in Construction Specifications Canada’s (CSC) June 2021 Construction Canada magazine on this topic. Perhaps a good topic for discussion on a future FHB Podcasts. Keep up the good work.

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Question 1: What type of wood works best as a durable exposed lintel over a window?

TamperjoeTamperjoe (from the FHB forums) writes: Hi all, we are building a modern Mediterranean home in Central Oregon. The exterior is stucco and stone and there are wood faux timber headers over the top of each window. See sample inspiration pic below. I am trying to decide on what type of wood would work best as a timber header; western red cedar, Douglas fir, or other. Something that won’t rot easily and won’t need yearly attention. I like the way cedar ages and turns gray over time but in central Oregon we get snow and low temps so I am not sure cedar won’t get moisture stains. I have Doug fir timbers in an outdoor patio/kitchen at our current home in the NW and the beams that see direct weather need pressure washing and stain every other year to keep them from turning black (and I’m losing the battle). Does anyone have any experience or advice about the type of wood that works best in this application?

I would also be interested in any flashing advice. I have solid plans and details for waterproofing and flashing for the top of the timber but I am concerned about the lower left and right corners of the timber. The timbers extend 4″ horizontally beyond the window frame so the lower left and right corners will be contact with the stucco. How do you keep water from getting trapped in the corners? Sorry for the long post and I appreciate any help. Thank you

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Question 2: Should I vent my mansard roof that will be on top of a conditioned third story?

user-7829614 (from the FHB forums) writes: I am currently designing a mansard roof which will become a new third story on top of an existing structure. The steep portion of the mansard will be clad in slate shingles over ZIP System Roof Sheathing and closed- cell spray foam insulation in the stud bays. The ‘flat’ portion of the room will be EPDM roofing over ZIP System Roof Sheathing over TJI’s with closed-cell insulation in the stud bays. Will it be necessary to provide ventilation baffles in the steep portion of the roof behind the slate shingles? In addition, should the flat portion of the roof also remain unvented? Venting the flat portion of the roof seems as though it will be inviting moisture-intrusion. Please note that the entire third floor space will be conditioned.

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Question 3: Can I pull out the metal straps I found under my old carpet? And should I be worried about old water stains on a plywood subfloor?

Dan writes: I am removing 30 year old wall-to-wall carpets in 4 bedrooms and installing new 3/4″ Solid Red Oak Hardwood (leaning toward 3 1/4″ wide). I have pulled up the rugs and see a few metal straps sticking out from the wall sill plate. See pictures. What are these straps and are they performing a needed function? Can I just cut them out?

Also, I have a couple areas near outside walls where the plywood subfloor has water stains from past water intrusion issues (leaky roof/windows). The water intrusion was resolved years ago, but was wondering how to determine if the subfloor is okay or do I need to replace stained portions? It seems structurally sound and is not delaminated or swollen, I do have some hairline cracking (have some hairline cracks in other non-stained areas also). I read that if the subfloor is water damaged, it could impact the flooring nails’ holding strength? Provided picture of worst water stain which is in a closet. Any comments or suggestions appreciated.

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Question 4:  Do the construction details on the “Lakeside Living” house only make sense in a mild climate?

FHB #300, July 2021

Dack writes: Hello FHB Podcast People! Love the show. It’s the first thing I listen to on Saturday morning. The house on the cover of the July 2021 issue is awesome, especially the “outdoor room.” But I am wondering about a few things:

* Do you think this makes sense in climates any colder than Ontario?
* It looks like anyone staying in the upper level bedroom at the south end would have to go downstairs and then back upstairs (if they were staying there between October and March). Do you think this would end up getting tiresome over time?
* Do you have any suggestions on achieving a similar-type *indoor* space in a long, narrow box like the featured house? Perhaps dual garage doors that don’t look like garage doors? Let’s get weird.

Thanks for any thoughts. This is essentially the house I am designing now (except ours is 1 story).

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End Note:

High-performance ducts photoCaption this picture from Mike:

…plus, here’s one solution we found if you absolutely must use exterior ducts:

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Published at Fri, 18 Jun 2021 05:00:26 +0000