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How Most St. Louis County Roofers Get Attic Ventilation Completely WRONG


How Most St. Louis County Roofers
Get Attic Ventilation Completely WRONG

More Ventilation Doesn’t Always Mean Better.
In Fact, Too Much Ventilation Can Lead To Major Problems & Skyrocket Your Energy Costs.


Attic ventilation is one of the most overlooked and misunderstood components of roofing. So it’s no wonder that so many St. Louis County roofers get it completely, unequivocally wrong.

Here’s why…

Proper attic ventilation is a delicate balancing act between intake ventilation (soffit vents) and exhaust ventilation (gable vents, ridge vents, box vents, turbines, powered fans). The U.S. Federal Housing authority recommends one square foot of attic ventilation—evenly divided between intake and exhaust—for every 150 square feet of your attic. 

In other words, you have to strike a perfect balance between the two types of ventilation to achieve the best results. Otherwise, you’re looking at a whole heap of problems (which I’ll get to in a moment).

The issue is that a lot of roofers don’t take the time to accurately assess the proper systems and ratios for their customers’ homes. They take the approach of “the more, the better” and install as much ventilation as possible. 

If the roofer installs more exhaust ventilation than intake ventilation, it causes an imbalance. You need sufficient air exchange in your attic. Otherwise, it creates negative air space, which can cause conditioned air in your home to be pulled into the attic from items with unsealed openings (recessed light fixtures, exhaust-fan openings, etc.). If you cannot achieve a balanced system due to design flaws or other restraints, then it’s better to have more intake than exhaust.

Another common problem is roofers mixing different types of exhaust ventilation. When two exhaust systems are installed, the stronger one pulls air from the weaker one, which essentially turns the weaker system into intake ventilation. This can leave large areas of the attic unventilated, as well as cause weather infiltration.  

More Problems With Unvented Or Improperly Vented Attics

  • Moisture Buildup: Poor ventilation will allow moisture to accumulate in your attic, which can produce mold and rot.
  • Condensation: Houses are built tighter and more efficient than ever. It used to be that some heat would always escape through windows and doors. But with everything in today’s homes being so airtight, heat has nowhere to go but up. If that heat meets cold air in your attic, it will create condensation.
  • Overheated Shingles: Too much hot air in your attic can overheat your shingles, leading to problems like decomposition and granule loss. 
  • Higher Energy Bills: A hot attic equals a hot home. This means your cooling system will work overtime to compensate.
  • Ice Dams: Hot air trapped in your attic heats your roof, which melts the snow on top of it. The snow runs down the roof until it gets to a part that’s cold (usually the eaves beyond the exterior wall). The snow then refreezes, forming ice dams that can expand under your shingles and potentially create leaks.

How To Ensure Proper Attic Ventilation In St. Louis County

There’s no such thing as a “one-size-fits-all” attic-ventilation system. Every home is different, and therefore requires a custom solution to ensure optimal ventilation.

This is why it’s important to choose a roofer that takes attic ventilation seriously. When getting a roof inspection or quote, make sure the roofer examines your attic space. Then hit them with the following questions:

  • Do you adhere to the U.S. Federal Housing Administration’s 1/150 rule?
  • How do you plan to balance my attic’s intake/exhaust ventilation?
  • What kind of exhaust ventilation do you propose? (If they say more than one type, run away!)

Asking these three simple questions will weed out the roofers that get attic ventilation WRONG… saving you a ton of money and problems in the process.

At XteriorPRO, we provide custom ventilation solutions for all of our customers. Check out our Master Elite Roofing Installation page for more details. Then get in touch for a free roof/attic analysis and quote.