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  E.H. Lawrence Co., Inc., Construction & Remodeling Services, Chisholm, MN  

Information About Attic Ventilation \/

A properly designed attic ventilation system must be installed with new shingles to:

• Validate new shingle warranty.
• Help protect the attic from damage and moisture in the winter.
• Help shingles and roofing materials last longer.
• Help prevent the formation of ice dams in cold climates.

The Ideal System Must:

• Provide free flowing air along the entire under side of the roof deck for optimum results.
• Work year-round.

How Air Vent Ridge Vents Work:

Air Vent Ridge Vents are designed to provide exceptional weather protection and enhanced ventilation.  Ventilation is enhanced by the use of and external baffle that deflects wind and weather over the vent and creates negative pressure to "pump" air from the attic, resulting in increased airflow.  Air Vent products also feature a patented weather filter to provide further protection from the elements.

• Negative pressure enhances airflow.
• External baffle works at wind speed as low as 1.5MPH, and deflects weather away from the attic.
• Patented, internal weather filter provides added protection against weather, dust, and bug infiltration.
• Works year-round without energy.

Moisture-laden air is removed from the attic before condensation can cause structural damage.

Proper ventilation reduces moisture which can reduce the R-value of some insulation.

In the winter, ventilation helps keep the roof deck uniformly cool, reducing the likelihood of ice dams and water damage.

In the summer, heat build-up is minimized so living areas stay cooler and air conditioners run less.


The concerns typically encountered with unsuccessful cold roofs include:

• The airway is too small or blocked.
• Ventilation in the attic is constricted or blocked at the outside walls where the vertical distance between the roof and the ceiling is minimal.
• Airway inlet is inadequate.
• Airflow is blocked in rafter spaces by cathedral ceilings, hips, valleys, and roof penetrations such as chimneys and skylights.
• Screen mesh openings at the eave or ridge are too small or clogged with snow debris and do not allow adequate free air movement.
• Ridge ventilation is inadequate or placed so that it becomes obstructed with snow.
• Roof penetrations add heat to the cold ventilation space.
• Air ex filtration allows excessive heat loss from the building due to inadequate or poorly installed insulation.
• At high elevations above sea level, high intensity solar radiation shines more directly onto south facing roofs. On those that drain to a shaded area, the melt water refreezes. Generally, a simple roof makes it easier to create a design that will require less maintenance in a mountain environment. Skylights, chimneys, and dormers create shaded areas and are difficult to vent around.

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