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 an exemplary rental. 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.
Here is a photo album of the shingle overlay process, done by myself alone after on-roof delivery.
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 tri-sodium phosphate and 20 mule team borax. 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 experience the ease of overlay shingling past the first of three 4" fan ducts.
Press the next shingle to the 1" tall throat of the penetration adapter and stab with an awl to break away a divot. A tin snip doesn't work nearly as well.
With a nod to ordinary, expected appearance, I will fit the next shingle row by cutting a 6 1/4" width slot about the square raised base of the roof cap. Do the same for all three 4" fan caps.
This is not a simple house. That first fan cap reset is over an added half-bath in the kitchen. The third of the three 4" caps is for passive radon venting. The house has 1 1/2 baths.
See the half-bath construction as a pair of walls with a pocket door, joined to new kitchen cabinets.
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 PBK 6 BK, 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!
Reveal the roof closure with a 6" penetration adapter and its' transferred flapper..
Stab out a circular divot around the adapter throat.
And fit a full circle cutout.
With little nibbling of top-layer shingles, the rain barrier hinges down, perfectly aligned with and coupled to the duct and fan below.
As with the 4" fan ducts, produce an expected tuck with the cap captured only by the two screws at bottom. This is not full surrender to expected appearance. For fan retrofit to a good roof, always employing a penetration adapter, I will continue to defend that the cap is only a rain cover, perhaps not tucked at all.
Now, regret all surrender to expected appearance. Shingle edges covering the cap are not well-protected against lift and tear-off with high winds. Did I tar them here? Did I apply screws at the cap upper-edge, now captured?
See a fixed relationship of the kitchen Panasonic in-line fan, and its' roof penetration adapter, fan strapped-up and pinioned from 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.
Here is a cross section of the kitchen 6" duct first-course shingling:
With this cross-section view, recall concern that the caps' discharge screen area is not generous. The air path is needlessly resistive. Whai if I am unhappy with fan performance and want to try a better cap?
Famco offers a better, Goose Neck cap:
With either, I am at present burdened to nibble out the stem and flapper. With either, I might want to lift the modified cap from the roof to clean or fix the screen. Note the ease of swapping Famco caps. Note that an uncertain seal between the body and the plate is no longer of concern.
The new roof overlay is especially white in this Google Summer mid-day satellite photo
My renters found no need of air conditioning in Summer 2024. Their resort is to one master bedroom window unit that interferes with usually-wanted natural ventilation.
