Industry News

How to Minimize Buckling of Asphalt Shingles

Of all the residential roofs in the U.S., 95 percent are sheathed with wood structural panels. This is because the panels are easy to install and form an excellent substrate for finished roofing, such as asphalt shingles. Proper installation is important, however, to ensure optimum performance of the shingle roofing and reduce roof callbacks and complaints. Roof coverings, such as asphalt shingles, may show some waviness when moisture conditions cause the roof deck substrate to move. To prevent buckling, follow these simple guidelines… Read the full article.

Attic Ventilation is NOT Just a Summertime Concern

Balanced Attic Ventilation Helps Fight Wintertime Moisture and Ice Dams

Read the full article at RoofingContractor.com.

The Edge Vent Passes 30-Day Ice Dam Test

The Edge Vent withstood a stringent 30-day ice dam test conducted at PRI Construction Materials Technologies in a simulation designed to give further confidence to roofing contractors using the roof-top intake vent in northern climates. Even after an ice sheet built up over the entire Edge Vent, at no time during the testing did The Edge Vent leak. Read the test highlights and the full third-party report authored by PRI.

The Edge Vent was intentionally covered under an ice dam for 30 days. It did not leak.

International Residential Building Code Changes for 2012 Announced

The International Residential Code for 2012 has been published and is ready for local municipalities to adopt effective January 2012. It includes attic ventilation changes that resulted from the efforts of the Roof Assembly Ventilation Coalition, of which Air Vent is a member. Below we have listed sections of the code language and highlighted the specific changes and their significance.

The IRC 2012 for Roof Ventilation will read in part as follows:

R806.1 Ventilation required. Enclosed attics and enclosed rafter spaces formed where ceilings are applied to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain and snow…

R806.2 Minimum vent area. The minimum net free ventilation area shall be 1/150 of the area of the vented space.

Exception: The minimum net free ventilation area shall be 1/300 of the vented space provided one or more of the following conditions are met:

In Climate Zones 6, 7 and 8, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.
At least 40 percent and not more than 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the attic or rafter space… with the balance of the required ventilation provided by eave or cornice vents.

R806.3 Vent and insulation clearance. Where eave or cornice vents are installed, insulation shall not block the free flow of air. A minimum of a 1-inch (25mm) space shall be provided between the insulation and the roof sheathing and at the location of the vent.

R806.4 Installation and weather protection. Ventilators shall be installed in accordance with manufacturer’s installation instructions…

What Changed?

The exception for reducing the attic ventilation area from the 1/150 ratio to the 1/300 ratio when a vapor retarder is installed on the ceiling now only applies to cold-weather climates.
The exception for reducing the attic ventilation area based on cross ventilation now requires no less than 40% and no more than 50% (previously 50% and 80%) of the required ventilating area to be placed in the upper portion of the roof.
The code now clarifies that vents must be installed in accordance with the manufacturer’s installation instructions.

Rooftop-Installed Edge Vent Solves Various Intake Ventilation Problems

One of the leading causes of attic ventilation problems is insufficient or incorrectly installed intake ventilation. To work efficiently an attic ventilation system must be balanced with intake and exhaust vents.

Air Vent, the leading manufacturer of residential attic and foundation ventilation products, has recognized this fact for years after extensive laboratory and field testing. Unfortunately, intake is often overlooked. Perhaps it’s because the roof design makes installing intake vents impractical (no overhang). Maybe it’s because the contractor doesn’t want to hassle working overhead cutting into the soffit/eaves.

Read the full story at Roofing Contractor

Air Vent’s Five Attic Ventilation Traps to Avoid

Use the right type of attic vent for the right project and roofing contractors can expect efficient performance and energy savins from the attic ventilation system. But sometimes, roofing professionals become frustrated because they’re stuck in one of the following traps they’d be wiser to avoid.

Read the article published in Roofing Contractor, February 2011 issue

University of Florida Research Confirms
Attic Ventilation Reduces Moisture Buildup in Hot, Humid Climates

Data collected at the University of Florida Energy Park (Gainesville,FL) under the guidance of Dr. Wendell Porter and Barrett Mooney supports the benefits of a balanced attic ventilation system. The research was presented at the 17th Symposium on Improving Building Systems in Hot and Humid Climates August 24, 2010 in Austin, TX. In their research paper they summarized data collected from 2001 to 2006 specifically analyzing the impact balanced attic ventilation has on moisture control in attics in hot, humid climates. In the study, Air Vent’s ShingleVent® II ridge vent (a copolymer, shingle-over ridge vent) was used for exhaust and Air Vent’s aluminum continuous soffit vents were used for intake. The research paper focused on data collected in 2006:

“A ventilated attic possesses many advantages for a hot, humid climate,” Porter and Mooney write. In particular the paper points out:

Relative humidity remains well below that of the external environment
Condensation on roofing members is rare
Moisture is removed quickly

The researchers write: “A ventilated attic supports cost effective, energy efficient climate control of unconditioned spaces in hot, humid regions. …The resulting data describes a climate that maintains a steady resistance to saturation providing a solid barrier to the elements. This climate serves to remove moisture at a rate consistent with the prevention of mold and mildew growth, and in the event of moisture intrusion can alleviate damage to insulation and prevent seepage into the conditioned space. …It is possible that sealing the attic spaces entirely and insulating the structure would reduce the thermal heat transfer from an attic, but this would provide no outlet for moisture transported through porous roofing materials or past the ceiling plane. …This investigation concludes the conditions in a ventilated attic are stable through seasonal changes and promotes cost effective, energy efficient climate control of unconditioned spaces in hot, humid regions.”

Read the entire research paper “Internal Microclimate Resulting from Ventilated Attics in Hot Humid Regions”

Read our condensed version of the U of FL research—“Balanced Attic Ventilation Reduces Moisture Buildup in Hot, Humid Climates”

Air Vent has partnered with Oak Ridge National Laboratory

Air Vent has partnered with Oak Ridge National Laboratory in constructing energy efficient homes as part of the ZEBRAlliance—an alliance maximizing cost-effective energy efficiency in buildings. Air Vent’s gable-mount solar powered fans are being used in some of the test homes. You can read more about the project by clicking on the link below.

http://www.zebralliance.com/about.shtml

Roof Assembly Ventilation Coalition

Increasingly Air Vent is hearing folks question if it’s really necessary to vent an attic. “Why not seal the attic and not worry about venting?” is what we are hearing because some research is making the claim it may not be necessary to vent.

Through the Asphalt Roofing Manufacturers Association Air Vent (and many of our fellow vent competitors) are pooling our resources to combat this argument. We’re organized under the “Roof Assembly Ventilation Coalition” under the arms of ARMA.

Read more about the debate to ventilate attics in this white paper prepared by RAVC:
Debate over Sealed Attics vs. Ventilation Intensifies Amid Calls for More Scrutiny

To learn more about visit the Roof Assembly Ventilation Coalition website.

Before;
Unbalanced

After;
Balanced

Air Vent Case Study: Balanced Attic Ventilation vs. Unbalanced Attic Ventilation

Air Vent partnered with Risk Management and Engineering to study a house in Mansfield, TX (a suburb of the Dallas-Fort Worth Metroplex) analyzing temperature readings in 30 different attic and living space locations. On both the “before” (unbalanced attic ventilation) and the “after” (balanced attic ventilation) test days thermo-graphic photo readings were taken during 12-hour periods on days with similar maximum outdoor temperatures and solar insolation (the radiant heat energy from the sun that heats the roof deck).

The unbalanced attic consisted of a mix of ridge vents and electric power fans without intake ventilation. The balanced attic consisted of electric power fans repositioned for maximum efficiency and Air Vent’s new Edge Vent™ – a shingle-over intake vent.

Read more about the case study in a three-page “Executive Summary” (PDF 76k)* authored by the 3rd Party RME or our one-page “quick hit” summary (PDF 1MB)*.

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