Why Your Roofing Company Needs to Properly Ventilate Your Attic

by | Nov 12, 2015 | Home Maintenance Tips

Attic VentilationAre your roof and attic well ventilated? This question is important because insufficiently ventilated attics can cause damage to your home.

Here’s why you want to ensure you have a properly ventilated attic:

Ice Dams

Living in southern Ontario, our biggest concern with poorly ventilated attics is the formation of ice dams.

When ice on your roof melts, runs down your roof, then freezes again (usually in the eavestrough), it forms an ice dam. As more and more snow melts and follows the same path, it runs into the ice dam and gets stuck. Water can get forced up under your roof shingles and underlayment, which can cause lasting damage to your roof.

Ice dams that aren’t quickly dealt with can even cause extensive (and expensive!) damage to your insulation, ceilings, or walls.

Insufficient ventilation triggers ice dams because your home loses too much heat through the roof, which melts the snow.


In the summer, poorly ventilated attics face a different problem – overheating. If too much heat builds up in the attic and has nowhere to go, it can:

  • Prematurely age your roof and shingles
  • Warp or otherwise damage wood framing
  • Damage siding, paint, and/or wallpaper

Moisture Buildup

Lots of things in our homes generate moisture. We generate moisture when we cook or take a shower, for example.

An attic with poor ventilation will collect this moisture. From there, it can cling to the underside of the roof and get into the attic insulation. When this happens, homeowners can find these problems:

  • Reduced insulation efficiency
  • Roof deck warping or rotting
  • Mildew or mould growth
  • Shingle buckling

Shingle Warranties

To avoid the damage caused by poor ventilation, building codes specify ventilation standards based on best practices. Shingle manufacturers typically include these standards in their warranty documents as a requirement for the warranty to be valid.

If you don’t have proper ventilation, you could end up with no warranty to cover your shingles if they need repairs.

Roofing experts and building codes typically recommend 1 square foot of attic ventilation for every 300 square feet of attic space, but this can differ depending on roof structure or the climate. Next time you hire a roofing company for a new roof or for roof repairs, you should inquire about whether you have adequate attic ventilation.

>> Herb Lodde Roofing provides full roof replacements and repairs. We can assess your roofing ventilation and make improvements if necessary. Contact us today!

Serving homeowners in St. Catharines, Burlington, Niagara, Hamilton, and Oakville.

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