Jacksonville Roofing: Article About Roof Ventilation Basics
In an un-insulated, un-vented home, heat, humidity, and air vapor build up in the house and create condensation and moisture problems in the rafters and attic. Even everyday living compounds this problem since a family of four creates about four gallons of vapor a day just by breathing, showering, cooking, and cleaning. All of that accumulated moisture and heat needs to be vented out of the house or it needs to be mitigated, and that's where a professional Jacksonville roofing contractor is helpful.
A variety of considerations go into determining the best level of attic and roof venting. Many experts recommend that a home have at least one square foot of vent area per 300 square feet of attic floor space, but there is growing evidence that un-vented roofs are better in areas where hurricane-force winds are prevalent. In addition, homeowners with asphalt shingle roofs must follow manufacturers' vent requirements to keep shingle warranties valid. An experienced local roofer will take all of these factors into account and consider the home's structure and attic insulation to determine the best level of roof ventilation.
If the roofer and homeowner decide to install passive roof vents, there are a variety of options.
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For bringing fresh air into the home, soffit vents are most commonly used. These vents fit under the home's eaves and contain small slits or holes that allow outside air to pass through into the attic.
For expelling moisture and hot air from the home, ridge vents are popular choices. Ridge vents are placed along the length of the roof peak, or ridge line, and are capped with an external baffle to prevent wind and dust from entering.
Other passive outflow vents include gable vents, wall louvers and wind turbines. Gable vents are usually installed as high as possible on the gable end of the home. Wall louvers are often square or rectangular vents with angled slats, allowing air to flow outward while preventing debris or dust to flow inward. Wind turbines and can vents use fan blades to help warmed attic air leave the home.
Some building experts believe that proper attic insulation is even more important than venting for keeping moisture, mildew and heat from building up in the attic and damaging the roof system. The science of balancing a home's humidity, heat, and airflow is evolving every day, so it's important for homeowners to work with their roofing experts to find the right venting, attic insulation, and roofing systems that optimize their homes' efficiency.