Repair of a Leaking Attic High Vent, Employing A Roof Penetration Adapter

This post of an action in 2016 is important in a Year-2025 campaign for broad employment of "roof penetration adapters" in residential roofing. Click the hyperlink to find a reverse chronology of all of my writing on this subject, in this blog.

Clarification is needed, whether penretration adapters are needed at attic high vent caps. They do have virtue. Please read on.

Here is a leaking condition that had recurred about once a year when high winds and driving wind would create a siphon under an attic high vent:

March 13, 2016

See that this attic vent was blindly cut in by roofers, without awareness of roof joist locations, as a new requirement on a home built in 1970. It would not have happened with a shingle tear-off.

A new problem was introduced in a re-roof, with cap misalignment from the shingle and sheathing cuts.

There are solutions against these misalignments. Immediately defy the siphon by stuffing a shingle bridge under the roof cap.

Better with a new venting opportunity on an already-shingled roof, let the vent locations be piloted from within the attic. Let all holes be circular, cut from the roof about the pilot hole. Insert a penetration adapter then to divert water flowing down-roof. Thereafter in a tear-off, center the adapter on the roof cut.

An imperative of easy and safe freedom in-attic to place high vent pilot holes would have been served by my self-funded campaign of Mandatory Attic Access Walkways. Know that vents clog over time from the inside. Circular high vents might have more promise of long unobstructed service, than roof-peak slots. A high vent cap should be easily removable for cleaning, from the roof,  without pulling any shingle nails.

Get the idea of the new-roof high vent installation process from rework of a found 4"  roof cap, now to serve a strong kitchen exhaust fan with 7" ducts. My roof adapter has bore 7 1/2" ID, 1 1/2" tall, formed of spun aluminum. The available roof cap is Famco 8". The 2x8 board has deck screws that when worked into composition shingles about the pilot screw will enable a well-defined sheathing cut by Sawzall. This is the same-size adapter plate that was tried by a very competent roofer under my instruction, to fix my leaking roof high vent.

Construction Metals RV38 Vent Cap Over Added 7.5” Roof Penetration Adapter

The penetration adapter is one shingle row deeper than the roof cap. A lower shingle bridge stops possibility of siphon action, even without the penetration adapter. The penetration adapter is redundant except as a can’t fail locator of the sheathing and shingle cuts. The adapter is locked in posution where it is attached to a duct. For a non-ducted roof cap, set it permanently upon the sheathing cut using upper-edge screws or nails. With a firm-set adapter rim, cut replacement composition shingles by stabbing-around with an awl; then breaking away the divots.

A further virtue of the adapter is in allowing a powered fan to be set in place of a static vent, without disturbing roof shingles, tiles or metal sheeting. Want all powered fans to be freely removable for service or replacement, without disturbing roofing.

The leaking vent was repaired including employment of a 7 1/2” spun-aluminum duct penetration adapter. Opportunity of better alignment with the roof cut was missed, and the use of shingle bridges is unknown. There has been no return of leaking. If respected, this will be an example to a roofer someday of ensuring alignment with the sheathing cut. Wish that better alignment of the adapter will be chosen. Wish the cut of plywood ang skip sheathing had not been excessive. Sharp corners are stress risers for lumber splitting.

We find that very many bath fans and kitchen exhaust fans are badly, even dangerously ducted. In any existing home the rather frequent retrofit of a new fan is not subject to building codes/ permitting review. Awful access to the attic contributes to the problem. I see this as a unique engineer/ inventor/ contractor/ technical writer. From age 60 twenty years ago, I have been a general contractor focused mainly on attics and crawl spaces. I know that dirty, awful work, delegated, is without learning and practice with ever-better materials, methods and procedures. I demand that practice of myself and am unaware of another like-minded attics person anywhere.

A roof penetration adapter is very useful when a roof cap is served by a through-roof duct. We shall want that all roof caps and roof-top powered fans are removable for service or replacement, without need af attic entry.

A ducted roof cap with a stem invites others to bond the duct to the cap; then removable only with attic entry. My preference is that ducts shall be galvanized steel "warm air" pipes. The crimped end is upward toward the roof, engaging often as an elbow, to full, tight penetration of the adapter plafe throat. Slight maneuvering of the adapter in a reroof shall not decouple the duct somehow strapped-up.

There shall not be compromise aiming of a duct pipe or flimsy plastic thing toward an existing attic high vent cap. There shall be no capping over framing or roof sheathing at a static vent cap, with a common "duct starter" plate, the usual practice wrongly taught to weatherization contractors.

 At 2025 there is a wrongful trend to offer duct-served roof caps only with long stems that reach into the attic. There is at least one cap manufacturer with thinking somewhat like mine.

 InOvate/ BetterVenting 

Product RoofNeck

Employed with 4" stemless caps for clothes dryer ducting. This is a rolled-in plate with a pipe length necessarily reaching both directions from the plate. I do not want a rolled-in pipe engagement.

Where the adapter has a stem penetrating roof sheathing, it is securely indexed to the roof cut, but there is likelihood the pipe below will be locked to the stem by screws and tape. The RoofNeck is likely to be a nuisance in a re-roof, requiring roofer access to the attic. Roofers do not want this.

For an adapter without sheathing penetration, as I  offer of spun aluminum, some other means must index the plate to the duct. A crimped pipe end protruding through sheathing, works. I do not prefer an adapter with a long stem. It is so very much harder to interleave with shingles, requiring more nail pulling in an insertion through already-placed shingles.

Want one-piece adapter plates with a simple neck at least 1 1/4" tall, as formable in stamping of aluminum. If a short neck protruding downward is needed as a location index, let it be a separate galvanized steel pipe length, crimped end, inserted from the attic. The stamped upper protrusion has needs of leak-free permanence. The downward-extending 

Slow Progress In Solar-Powered Attic Ventilation

I missed the boat with a customer having only gable vents, no possibility of opening up soffits.

Observations were reported here:

Wednesday, September 5, 2012

A Residence Attic Ventilation Review 

I had pleaded with the roofer who would have opportunity in Summer 2013, to try something new. Please don't cut in roof high static vents, where there were none to start. High vents and gable vents clash unpredictably, with little net air circulation. I would come in after the reroof, and install a solar-powered attic fan at roof center. That fan, on hot Summer days, would draw cooling air through both gables. I got no call. Driving by last Fall, I found the usual static vents, over the peak on North side of roof.

No roof high vents, still, visible from the street.

I blame the missed opportunity of experiment, and still-hot attic for this customer, on slow progress in inspiring a manufacturer to offer a suitable fan. I had bought a  Solaro Aire  , with built-in PV array, for this job.

I brought the fan back to the factory and discussed concerns and wishes for something better. This fan has a 12.5" bore, and should require not more than a 12.5" roof hole. I was troubled by wasted metal spinning of rounded shape in the base, not a factor in aerodynamics, and then of not having means of adding a bellmouth draw pipe under the fan in the attic. Troubled that fixes I might devise should be offered by the manufacturer.

I am appalled by the installation procedure for the Solaro fan, as presented in this video . A 19" hole is commanded through shingles and sheathing. Nails are in the way of lifting shingles for the fan tuck of course. Just hack them off by swinging a reciprocating saw over sheathing, under all shingle layers. Rely on poor blind application of caulk, smeared-off in sliding, to stop wind-driven rain up the roof. Hope the reciprocating saw didn't develop leaks through tears. I would NEVER follow those instructions.

My wishes of better and of ever-constant learning, are driven by progress installing a Costco US Sunlight attic fan, as reported in this photo album:

Costco Solar Attic Fan 

I am unimpressed with aerodynamics of the US Sunlight fan, but accepted it. The customer made the choice for his convenience and cost savings. I insist upon sealing an adapter plate into the roof for any fan penetration, 4" bath fan, 8" static vent, 14" fan here, whatever. The fan body is only a rain cover, minimizing concern about blind tucking. Shingles are cut in a circle only slightly larger than the sheathing cut, and there is a maximum of shingle overlap upon the real seal of the adapter plate. High-quality caulk can be applied copiously with full visibility, and yet there is minimum reliance on caulk. I wish never to rely on caulk, at all.

Here are graphics conveying my wishes of better, to Solaro, and to all manufacturers.

The simple adapter plate is set atop roof membrane, sealed at top to the roof membrane. All involved lower shingle courses rest on the adapter plate.

Fan electronics are serviceable/ swappable, without impact on roof sealing. A bug-blocking screen will get fouled, and may be serviced from the roof as needed. Good fan aerodynamics include smooth draw through a bellmouth. If fan blades of larger diameter than the roof cut are better, let the fan reside below the flare or bellmouth. Let us get over treatment of attics as inaccessible trash pits as treated by the Solaro crew.

Here is my only Costco solar fan installation, over an accessible attic. 

A Residence Attic Ventilation Review

This is continuation of posts of  November 30, 2010, December 15, 2010, and February 20, 2012. 
Please pick:

Another Really-Nice Job, Done 
Excellence Is Better Value 
Sealing With Three Times The Value Of Added Insulation 

My customer was served with the exceptional diligence I demand of myself. Yet, attic ventilation was not improved. The only ventilation is in the gable openings, about 90 sq in at each end of the attic, and that has been adequate. There are no mildew problems in this attic, even though the bath fan is not yet ducted through the roof. 

The soffits seem to have ventilation paths, and I did not have the courage or mandate as an insulation installer, to question this.

I dutifully baffled all roof joist bays, not knowing where vents might come through. There was no visible light.

With re-roofing imminent, I have questioned the contracted provision of added ventilation paths, two new static vent cans near roof peak. No one has yet taken responsibility for soffit vents. I now see that the holes in the vinyl soffit facia are tiny, and are fully blocked by wood structure. Soffit reconstruction is not feasible.












We are left, then, with the option I have imagined all along. For high-summer heat, rely on a solar-powered roof fan, and enlarged gable vents. Place the bigger gable vents symmetric if possible, and partially shutter them, to fully open only when the roof fan is operating. For the roof fan, I like the concept of Air Vent, Inc. with a PV array facing South, separate from a fan on the back side of the roof, North here. None of the involved elements are mature, and I hope to find more-suitable products in 2013. While waiting, there has been little summertime heat burden, due to thorough attic insulation.

If a re-roof must proceed before I am ready with powered-fan elements, I will instruct through the home owner, that there be no high roof cans. Such static vents lead purists to say that gable vents get confused, and should be blanked-off. The argument in this is stronger if a continuous roof peak vent is considered. I think I have a better handle on the big picture, and will confidently lead to have things my way. Retain and improve the gable vents.

This review is for information to the contracted roofer, for conversation with Joe Lstiburek, a no-gable-venting purist, and for inspiration of solar fan and gable louver manufacturers, who ARE part of the solution. Case in point.

And I might stand corrected. Air Vent Inc. reminds me there is another option for low air intake, SmartVent. 

I approach this as a skeptic. SmartVent claims 9 sq in per ft net free area, nfa9, through a load-supporting edge 3/4" thick. I think that is impossible.

Nfa9,  is needed here, at one sq ft per 150 sq ft house area, 60% for inlet paths, in a solution of static venting only, no gable vents.










Job Revisited, November 2013

There is a further post at February 2014, addressing wished-for innovation in design and installation of solar attic fans.

Sadly, I find that the roofer brought into this job has disregarded pleas that he not add static roof vents where they serve no inlet flow paths. There is NO air circulation from lower down, and the new roof vents clash in function, with existing gable vents. There is only one solution to this new problem. The home now must have solar powered fans, and they must occupy both new static vents. The gable vents will serve always as air inlets while the fans are running. This is the direction I wanted all along, but think this small house would be better served by a single solar powered fan. I contributed to this new dilemma by not finding a suitable fan in advance of the reroofing.