Roof Ventilation

Condensation

Without sound roof ventilation, condensation may appear during the winter months. 

In the winter, warm and moist air rises through the ceiling into the attic and condenses on cold surfaces. The frosted underside of the sheathing causes several problems for Edmonton homeowners. The most common one is "attic rains" - the melting frost or ice dripping onto insulations and sometimes seeping through ceilings, bathroom fans and light fixtures. 

Pic: condensation around the bathroom vent duct.

Ice dams also happen when the snow melting/freezing cycle occurs at the eaves and gutters. This cycle can result in a pool of water and ice backing up under the shingles and behind the fascia boards. 

Pic: ice dams on the eavestrough and the roof edges. 

Having sufficient insulation (a rule of thumb is having at least 10 to 12 inches of insulation) and roof ventilation will remove warm, moist air from the attic space, reducing the risk of ice dam formation and attic condensation for most sloped roofs.

Roof Ventilation types

Duraflo offers a selection of vents for Edmonton homeowners. 

Standard Roof Vent (Box Vent or Roof Louvers) is installed close to the ridge to ventilate warm air out from the attic space. 

WeatherPro Turbo Roof Vent (Tall Vent) has a much larger 117 sq. in the net free area and stands tall on the roof. 1 Pro Turbo = 3 Box Vents. 

Ridge Venting allows smooth airflow over the ridgeline, maximizing effective ventilation from the attic space. They feature 18.3 sq. in. per linear foot of net free area. Ridge venting is used when the roof slope is shallow and has minimal attic space.

WeatherPro Slantback can be used as intake vents when the soffit ventilation is blocked or nonexistent. Soffit ventilation is located on the underside of the eave.

We also carry premium grade metal vents by Ventilation Maximum. 

Shingle Warranties

Shingle manufacturers require that the roof ventilation system meet local building codes. If not, the shingle warranty terms may be void.

Learn more here.

Roof Ventilation questions

1. Is the ridge vent the best vent? 

No, it is not. Ridge vents (like other roof vents) will work effectively only when a proper intake venting system is in place. Focus on installing a balanced ventilation system first. 

2. Most vents don't have turning parts. How do they work? 

A wind-driven flow of air (wind's speed) creates areas of high and low air pressure. High pressure forces air into the attic, while low pressure draws air out. High-profile non-powered ventilation designs usually do not require a lot of wind speed. The lower the wind speed requirement, the higher the efficiency of the vent. 

3. Are intake vents more important? 

For maximum efficiency, the net free area ("NFA") of the intake vents should be equal to or greater than the NFA of exhaust vents.

4. How should I vent vaulted ceilings? 

We recommend using a ridge vent system with an air space of at least 1" between the wood sheathing and insulation. Before installing ridge vents, a proper intake venting system must be in place. Without a balanced system, moist air can be pulled from the living space, saturates in the narrow attic space, which will promote mold growth and increase the risk of condensation. 

5. My home has a bad roof ventilation system. How much do you charge to upgrade them? 

We need to inspect your current system first before we price them out. There is no consultation charge if we can utilize GoogleMaps to figure out what is wrong with your current ventilation. And we can provide you with recommendations and a free quote.

In some cases, an attic inspection is required. Then, we will charge for the inspection. The fee is $300 or more. 

6. Can I do a roof ventilation upgrade in the winter? 

You may notice ice damming and attic rains during the winter months. To resolve the problems permanently, you may need to upgrade the roof ventilation system. For the best results and for safety reasons, roofing works should be performed from spring to fall, and not during the winter months. The cost is between $300 to over $1,200 depending on the scope of work.