In April of 2023 I had the opportunity to observe benefit of Roof Penetration Adapters of through-roof bath and kitchen fan ducts at roof caps, in a DIY overlay re-roof of my own home, now a rental.
A white roof will measurably reduce summertime heat burdens,* and reduce heating-season radiation loss of energy to night skies. This is Owens Corning Shasta White, not much in demand and in limited supply.
* Google and Yale Environmental 360 affirm this.
I don't worry about moss or other discoloration because my neighbor to the South taught me that roof life is extended by yearly application of a 50-50 mix of 20 mule team borax and powder laundry detergent. I have added a six year confirmation in this to that of 25 years for my neighbor. I didn't like using commonly and wrongly-applied copper sulfate.
Here, I confronted the steel roof cap of the 6" steel duct from the kitchen exhaust fan, Panasonic in-line. The roof cap is Famco PB6BK, modified with maximum circular enlargement of the back opening, salvaging the backdraft damper of the 6" pipe stem. See my as-always surprising treatment of the roof cap as merely a rain cover. There is no need to deeply tuck the cap under shingles. Not knowing the full story, a roofer will see this as error. That thing is going to leak!
A separate Roof Penetration Adapter here seen inverted, is under that roof cap, tucked even under roof membrane. A 6" pipe male end tightly engages the ID. My adapters for now are 12" square aluminum plates spinning-formed to about 1" tall upward stem. $25 each, hard work, not sustainable. Production adapters would be stamped inexpensively. I or some other fabricator, await demand. Reader: please get interested.
See a fixed relationship of the kitchen Panasonic in-line fan, and its' roof penetration adapter, fan strapped-up and resting upon plywood flooring over the R49 attic insulation.
Here a 6" steel warm-air elbow penetrates the roof sheathing and engages the throat of the penetration adapter. The roof cap without a stem is easily detachable without attic access. A cap with a stem, screwed and taped to the fan piping as required, would command attic entry.
The backdraft damper of a Famco PBK6BK Roof Cap is now riveted to this spun-aluminum 6" penetration adapter, captured in first-layer roof shingles. I think this should be the topside appearance of every fan-to-roof penetration. Advocate then that Famco should set an example in offering these separate components, rather than one-piece caps with stems. Every roofer might get comfortable with the offer of means to get the job done, without difficult, or impossible, attic access. Here, just accept that shingle-over is made much easier. In a tear-off the dampered adapter might remain nailed to sheathing; lace new membrane under and over.
There are no leaks anywhere in the thirty year old expired shingling I applied as a tear-off at house age fifty years, replacing much rotted 1x8 shiplap with a reserve of lumber found in the attic. The durable underlayment is 20 pound felt nowhere brittle, overlaying the penetration adapter of the four remodel fan ducts that I had installed over a span of twenty years; this the most recent. I trust the penetration adapter, now buried one layer deeper, to protect against leakage at any layer, for the life of my new reroof. Just snip the new shingles about a 6 1/2" circle. Roof cement at-the-ready for any first-layer rebuild, isn't of value here.
Reset the roof cap, now with less-pretty alignment to the shingle pattern.
With little nibbling of top-layer shingles, the rain barrier hinges down, perfectly aligned with and coupled to the duct and fan below.
Here is a job photo from a customer installation of a Famco PB8BK, with more challenge from hacked-in termination of a 6" kitchen exhaust with needless enlargement to an 8" cap then leaking.
The 8" penetration adapter with 12" square surround is tucked under scrap sheet metal or shingle that reaches as high as possible, directly against the underlayment, for full shingle effectiveness.
This is far better than simple jamming-in of a roof cap, which had leaked. If there is a second layer of shingles someday, this roof cap will still work with no diminished effectiveness.
See visible, smart use of appropriate gasketed screws.
