What You Should Know About Attic Ventilation

Each type of attic ventilation system basically works the same, it draws outside air through intake vents located at the eves of the roof or soffits and vents it out through higher vents like a ridge vent, gable vent, roof fan or static louver vents. When stale, overheated air is replaced by fresh outside air, creating an “air exchange”. For the attic ventilation to work properly, the volume of air intake must equal or exceed the air exhaust. How do you know if you have the proper amount? First you must speak to a trained roof and attic ventilation expert to determine the proper amount of ventilation for your home. Rule of thumb, for every 300 square feet of attic area you need at least 1 sq Ft. of attic ventilation.

Many homeowners do not understand how important it is to have the correct amount of attic ventilation for their roof. Without a sufficient ventilation system there are multiple problems that can occur from the moisture and heat that is being trapped in your attic. Without an equal balance of cool air intake and exhaust, there are many problems that may arise.

• Heat and moisture can cause roof structure, shingles and roof decking or sheathing to warp or deteriorate prematurely.
• Increased energy bills, when heated air is not being exhausted, it causes your air conditioners to work harder and longer.
• The excess moisture can lower the R-value of your insulation and create mold, mildew and or wood rot.
• Also in the winter poor attic ventilation will cause ice dams and leaks near walls, in roof valleys and over windows.
• Excess heat and moisture will not only effect the structure of your home but it will also cause damage to anything you have stored in your attic space.
• In the winter, any moisture from your home appliances or simply taking a shower can condense in your attic space, freeze to the underside of the roof and fall off to cause mold or mildew in your insulation or on the roof sheathing.

So now that you know what a roof ventilation system does and what it can prevent, here are the most common systems and how efficiently they work. A very popular system used in older homes, were gable vents. Gable vents are located on the gable sides of your home and should allow air to cross through your attic space from one side to another. In most cases, outside air is being sucked in through both vents and causes a cyclone of air in your attic, equals no air exchange.

Another common system used, are roof vents and roof fans. If you have lower intake or soffit vents and the correct amount of roof vents this system can work very well. The drawback to having multiple roof vents, is multiple penetrations in your roof. Any experienced roofing contractor will tell you that the less penetrations in your roof the better. In most cases a home will need several vents in order to have the correct amount of exhaust, this creates several more problem areas. Great way for insects and rodents to enter your home. Possible leaks with heavy rain or snow build up.

The most efficient and commonly used attic ventilation system is a ridge vent in combination with soffit vents. A 2-inch space is cut along the ridge line of your house and covered with a wind- baffle style cap-over type ridge vent. Along the soffit areas, holes or channels will be cut and covered with vented aluminum or vinyl soffit to be used as the intake part of the system. If there is insulation in your rafters, plastic or Styrofoam rafter baffles should be installed to allow proper air flow. The hot air rises and exhausts out of the ridge vent while fresh cooler air is being drawn in through the soffit vents.

Note: Only one of these systems should be installed on your home. If you use gable vents with a ridge/soffit vent system, the air will not exchange properly rather just sit in your attic.

The gable vents in this case would need to be either eliminated or closed off from inside the attic.

Price Rite Roofing & Siding will be sure to install the correct roof ventilation system for your home.