Raising the need for roof vents

Roof ventilation is key to protecting your roof and attic space. Attics and roofs need to breathe or they’ll start to decay. Remember, we produce a lot of moisture in our homes, from showering, doing laundry, cooking, doing dishes — even breathing. All these things lead to moisture in the home, and that moisture needs to escape or you’ll run into issues like mould and rot.

We know hot air rises and that it can hold moisture. As the hot air rises, holding that moisture, where do you think it will end up? In your attic, and once it’s up there you’ll get condensation.

You don’t want condensation in the attic. It will soak your insulation, making it lose its R- value ( a material’s resistance to heat loss or heat transfer). During winter, it can lead to frost buildup on the underside of the roof, which can cause issues such as mould on the roof ’s sheathing, rafters or trusses. Sometimes homeowners will think they have a leak — they’ll see a big stain on a ceiling — but really it’s just too much condensation in the attic.

Your attic is a cold zone — or at least it should be. That means it needs to be properly sealed off from the living space below with vapour barrier and insulation, and have a minimum R- value of R50.

The vapour barrier must also be properly sealed with Tuck t ape or acoustical caulking to help stop warm air and moisture from getting in.

That attic must also be ventilated, which means it’s necessary to have enough roof vents. How many you need depends on the size of the attic. The standard is one vent for every 150 square feet, but it all depends on where you live, or if there’s a vapour retarder on the ceiling of the room below the attic.

Insufficient ventilation can wear down a roof prematurely ( meaning t hat shingles can blister because of too much heat in the attic). That means re- roofing more frequently. So it saves you money to make sure there’s enough ventilation.

There are different types of roof vents, including: ❚ Box- style vents: These are the typical roof vent, squareshaped with the open side facing the ground. ❚ Soffit vents: These are the narrow horizontal section on the underside of a roof ’s overhang. They’re perforated, usually made out of vinyl or aluminum. ❚ Gable vents: These are located not on the roof but at the top of the wall on either end of a peaked roof. They tend to let in less moisture but they cannot work without wind. ❚ Ridge vents: These run along the peak of a roof to allow for continuous airflow. I love ridge vents but they’re more labour- intensive to install and more expensive.

Whether your roof has soffit or gable venting or ridge vents, the most important thing is that there are enough of them to ensure the attic is properly vented — and they cannot be blocked by insulation on the inside or by snow on the outside.

In one home, the roof vents on the north side of a home were constantly covered by snow. ( The north side of a home tends to get more snow accumulation.) This blocked the ventilation in the attic, which led to condensation. The homeowner thought there was a leak but it was just a roof venting issue.

The way to fix this? Raise all the roof vents on the north side of the home.

Also, when adding extra insulation in your attic — which is a great idea, especially before winter — make sure it doesn’t block the soffits. One solution is to use Styrofoam baffles that direct airflow from the soffit to the top of the attic. Something else I often find is old wooden soffits that have been covered over with perforated aluminum during an update or renovation, but no holes were made in the original wood soffit under the new layer of aluminum, which means there’s no venting.

We also need to make sure our roof vents are properly protected against critters. Squirrels love to chew through them and pull up the flashing that protects the roof area around the vent.

If you’re not sure whether your roof has enough ventilation, have a professional roofer take a look. It’s not a bad idea to get it checked especially as we move into winter, and usually the best roofers get booked up fast. If you invest in your roof, it pays you back.

YOUR ATTIC IS A COLD ZONE — OR AT LEAST IT SHOULD BE.