AN ARCHITECT’S PERSPECTIVE

The perimeter venting system uses passive means to extract moisture from the crawl space.

John Gresseth is the founder and managing partner of John Gresseth Architects in Friday Harbor, Washington. He graduated from the University of Washington in 1970 with a professional degree in architecture. He has been a licensed architect since 1977. Gresseth has used a continuous perimeter vent system on several projects. He was asked about his experiences.

How did you hear about the continuous perimeter foundation vent system?

Gresseth: I initially saw it at the Seattle Home Show.

Why did you choose to use this system?

Gresseth: The system is very well detailed and effective. The installation results in a clean look and provides continuous venting throughout the crawl space.

The installation is different from what is typical for foundation venting. Did this cause any problems in the construction phase?

Gresseth: Other than initial skepticism on the part of the builders (because of unfamiliarity) installations went well. In fact, I was at a housewarming recently where the builder commented on how he thought it was a very nice system. There were no problems in our jurisdiction from code officials once I supplied test results provided by (the manufacturer).

You specified the premium cover of extruded aluminum rather than standard white for your projects. Why is that?

Gresseth: The standard cover comes only in white. In fact, we painted the vent covers in one of our jobs.

What is your overall impression of the system?

Gresseth: I think [the system] is a superior product providing great, continuous venting and a superior finish look.

CASE STUDY: RESIDENCE, SEATTLE AREA, WASHINGTON

For the wet and humid Pacific Northwest, the continuous perimeter venting system provided a good solution to several problems.

For a custom home in the Seattle area of Washington, a continuous perimeter venting system was chosen after the typical ventilation method was deemed unacceptable for several reasons.

“In this market, we don’t have a lot of options for venting crawl spaces,” says Brian Finney, a project manager residential construction industry.

What is typically found in the wet and rainy area are typical 8-inch x 16-inch boxes or rim vents, Finney explains.

However, such a venting system requires a buildup of 8 inches to accommodate the boxes. And whether that vent is in the stem wall or the rim, “that vent is a requirement in each and every jurisdiction so it’s got to happen,” Finney says.

In the area where Finney works, the topography includes a lot of sloped lots, and that creates a lot of grading obstacles to overcome.

With this particular build on a view lot, Finney had a target mark that he had to hit in height. Specifying the perimeter venting system allowed him to eliminate that 8 inches of foundation he would normally need for conventional vents.

“It doesn’t seem like that much, but in reality, you can accomplish a lot with 8 inches,” Finney says. “This system allows the house to sit low and have that low-sitting profile, not standing out of the ground too proud.”

Finney says the perimeter system “just makes your project look better from the curb. It’s a benefit to be able to look at the house and not have it too proud out of the ground or be looking at those vents.”

According to Finney, the venting function achieved with the perimeter system is also superior. “Typically, you’re looking through your plans and looking for the optimal place to put the traditional 8-by-16 vent,” he explains. “With those 8 by 16s being randomly placed, you can get the draw and the draft and the airflow, but the airflow isn’t continuous, and it’s not even. When disturbed, it starts to diffuse, and that flow isn’t really there like you would get with a continuous perimeter vent system.”

“And I didn’t have to worry about vent wells and keeping the grade of the land away from these vent pockets,” he adds. “So you’re not only meeting but exceeding the venting that’s required by jurisdictions.”

On the project, Finney also used the continuous vent system for the soffit. The system fit in well with the contemporary design and produced a clean look. “All the louvers are concealed so you just see a continuous trough up in the eaves. It has a really good look to it,” he says.

For building professionals who might want to specify a perimeter venting system, Finney suggests choosing a manufacturer that is very involved with the project and supports the architect with the design. Lead time and how quickly a manufacturer can get the product to the site are also concerns.

“For me, it was the only solution we had to accomplish what we had to accomplish here,” Finney says. “This is one of the best venting solutions for homes in really wet, damp climates where you want that house to breathe really well. It’s your truest, purest crawl-space vent.”