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 in a first or second reroof of the home built in 1970.

A new problem was introduced in the blind placement of the roof vent cap, badly misaligned with the shingle and sheathing cuts.

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 cut. Cut replacement 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 shingles.

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 edges 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 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.

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.