Can An Attic Vent Fan Extend the Life of a Roof?

Many homeowners have heard discouraging news from roofing contractors telling them their roof is ruined years before it should need to be replaced.  The cause is often excessive heat or moisture in the attic, problems that can be resolved with the installation of an attic vent fan.  In this roof guide we discuss problems caused by heat and moisture, the value of attic ventilation, and how an attic fan can extend the life of a roof and protect trusses and the roof deck as well.

How Heat Destroys a Roof

Heat can build up in attics in sunny, warm weather, often to temperatures in excess of 150 degrees F.  Heat rises, so the hottest layer of air is right against the roof itself.  Asphalt shingles are especially at risk from excessive heat.  It can cause them to shrink, usually at the edges first, and this will lead to cupping, curling, or splitting.  Consistently being exposed to high temperatures will also cause them to become brittle, and when this happens they are easily damaged by wind, hail or someone walking on them.

Similar problems may occur with wood shakes or shingles, especially when they get excessively dry.  They may split or crack and can also become very brittle.  Inspect your roof on a regular basis and if you see any of these signs in the asphalt shingles or wood shakes or shingles, you may have a problem.

How Moisture Destroys a Roof

Moisture gets into your home in one of two ways generally.  First, if your home isn’t well ventilated, moisture from your bathrooms, laundry, kitchen and elsewhere will find its way into your attic along with rising heat.  Secondly, as your attic’s trusses cool at night, moisture tends to condense on them and absorb into the wood.  A roof deck — the sheathing that forms the wooden base of the roof below the shingles or other roofing material — with too much moisture in it might eventually rot or at least warp, causing severe damage to any type of roofing material that is on them. If you inspect the interior of the roof and find wood that is wet, has mold on it, or staining from previous moisture, you’ve problem got a moisture problem.

Excessive heat and moisture in attics are common roofing problems in many homes.  Now let’s look at the solution.

Ventilation is the Key to Roof Durability

Ventilation brings cooler air into the attic space in the summer and drier air into the attic space in the winter, resolving the conditions that cause the problems.  Proper roof ventilation is produced by a combination of ridge vents, gable vents and soffit vents.  The basic problem with these types of vents however, is that they are passive.

How an Attic Vent Fan Can Extend the Life of a Roof

An attic vent fan is active ventilation and vastly improves the climate in the attic over passive ventilation only.   They can be installed either in the roof or high in up in the gable, near the peak.  When activated, they push hot air out of the attic and draw cooler and/or drier air into the attic through the passive vents.  In summer, the attic vent fan will extend the life of the roof by ridding the attic of damaging heat and in winter it improves roof durability by flushing moist air out of the attic and drawing in air that is less humid.

Placement of an Attic Fan

Where the ventilation fan is installed is crucial.  An attic vent fan can extend the life of the roof it is placed where it will draw air in from all around the roof.  For this reason, a fan with a large enough capacity needs to be purchased.  Attic vent fans are typically sized by the CFM, or the cubic feet per minute, that they can move.  They are also rated for a specific number of square feet that they can serve.

The physical installation is something that many DIY homeowners can handle, but it is knowing where to place the attic vent fan that may require the expertise of an experienced roofer.  If you’re concerned about the longevity of your roof, inspect your roof for signs of common problems associated with heat and moisture.  Call a qualified roofing contractor to assess the ventilation in your attic and to discuss with you the benefits of installing an attic ventilation fan to improve the durability of your roof.

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