Roof Ventilation
Roof Ventilation is a system of intake and exhaust that creates a flow of air. Sound roof ventilation keeps attic airflow all year round, creating cooler attics in the summer and drier attics in the winter.
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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.
Frequently Asked Questions
1. Why is roof ventilation important for my home?
Roof ventilation is essential because it regulates airflow in the attic space, helping maintain a balanced temperature and moisture level. Without proper ventilation, heat and humidity can build up, leading to premature roof aging, mold growth, and structural damage. In summer, ventilation helps release trapped heat, reducing strain on cooling systems. In winter, it helps prevent ice dams by keeping the roof temperature more consistent. Overall, it protects both the roof system and the home’s energy efficiency.
2. How does proper ventilation extend roof lifespan?
Proper ventilation extends roof lifespan by reducing extreme temperature fluctuations and preventing moisture accumulation. When heat and moisture are trapped in the attic, roofing materials can deteriorate faster, causing shingles to warp, crack, or lose adhesion. Ventilation helps maintain a stable environment, protecting the underlayment, decking, and shingles from unnecessary stress. This balance significantly reduces long-term wear and delays the need for repairs or replacement.
3. What are the signs of poor roof ventilation?
Common signs of poor roof ventilation include excessive heat in the attic, musty odors, mold or mildew growth, and visible moisture or condensation on roof decking. Homeowners may also notice curling shingles, ice dams forming in winter, or higher-than-normal energy bills. In some cases, peeling paint near roof lines or damp insulation can also indicate ventilation issues that need immediate attention.
4. Can bad ventilation increase energy bills?
Yes, poor roof ventilation can significantly increase energy costs. In summer, trapped heat in the attic forces air conditioning systems to work harder to cool the home. In winter, uneven temperatures can contribute to heat loss and ice dam formation, which further reduces efficiency. Proper ventilation helps regulate indoor temperatures, easing the workload on HVAC systems and lowering overall energy consumption.
5. What types of roof ventilation systems are available?
There are several types of roof ventilation systems, including ridge vents, soffit vents, gable vents, roof turbines, and powered attic fans. Ridge and soffit vents work together to create continuous airflow along the roof structure. Gable vents are installed on exterior walls, while turbine and powered fans actively pull air out of the attic. The best system depends on the roof design, attic size, and climate conditions.
6. How does ventilation prevent moisture buildup in attics?
Ventilation prevents moisture buildup by allowing humid air to escape before it condenses inside the attic. Everyday activities like cooking, showering, and laundry release moisture that can rise into the attic space. Without airflow, this moisture settles on cold surfaces, leading to condensation, mold growth, and wood rot. Proper ventilation continuously cycles fresh air through the attic, keeping it dry and structurally sound.
7. Can poor ventilation void roofing warranties?
Yes, in many cases, poor ventilation can void roofing warranties. Most manufacturers require proper attic ventilation as part of their installation guidelines. If damage occurs due to heat buildup or moisture caused by insufficient ventilation, the warranty claim may be denied. This is why professional roofing systems always include a balanced ventilation setup to ensure both performance and warranty protection.
8. How often should roof ventilation be inspected?
Roof ventilation should typically be inspected at least once a year, often during routine roof inspections. It’s also recommended after severe weather events or if homeowners notice signs of attic heat or moisture issues. Regular inspections help ensure vents are not blocked by debris, insulation, or pests, and that the system is functioning properly to maintain airflow efficiency.
9. Is roof ventilation necessary in cold climates?
Yes, roof ventilation is especially important in cold climates. It helps prevent warm indoor air from causing snow on the roof to melt and refreeze at the edges, which leads to ice dams. These ice dams can cause leaks and significant roof damage. Ventilation also reduces moisture buildup from indoor heating systems, protecting insulation and structural components throughout the winter season.
10. Can ventilation be added to an existing roof?
Yes, roof ventilation can be added or upgraded on an existing roof. In many cases, contractors install additional soffit vents, ridge vents, or attic fans without requiring a full roof replacement. The process typically involves assessing current airflow, identifying problem areas, and strategically adding vents to improve circulation. This upgrade can significantly improve roof performance and energy efficiency without major reconstruction.
