Overall, our homes are more weather-tight than they were 20-30 years ago and tighter homes trap a larger amount of moisture in them. Indoor moisture is generated by every activity that uses water, including: dishwashing, mopping floors, doing laundry, cooking and even breathing. It is believe that the daily living activities of a family of four can add more than 18 gallons of water a week into the air of a home. Through the natural equalization process the flow of moisture is towards the drier areas of the home which typically include the attic space.

A secondary cause of moisture in a poorly vented attic is by simple condensation. The air inside an improperly vented attic will be warmer than the air outside. When warm, moist air comes in contact with cold sheathing condensation occurs.

Net Free Area or Net Free Venting Area is the method of measurement used by the roofing industry. It is the open area of a vent through which air can pass unobstructed.

All exhaust type roof vents are to be installed on the upper 1/3 portion of the attic area. Intake vents are generally installed in the under-eave/ overhang or fascia area.

We have a WeatherPro® Series product line that has a WeatherPro patented internal baffles which deflects water and snow, allowing it to drain harmlessly out the drainage opening. The WeatherPro® Series product line is designed to allow high airflow while providing excellent defense against weather infiltration. We have three product groups to choose from: WeatherPro® Turbo, WeatherPro® 50 Roof Vent and the WeatherPro® Ridge Vent. These products are tested and approved by CSA and Miami Dade County.

Ventilation products are part of a system of intake and exhaust vents. As long as the amount of NFA system is balanced, (approx. 50% exhaust and 50% intake), roof vents, ridge vents, or turbo vents will be equally effective.

A cathedral ceiling can be one of the most challenging ventilation scenarios. We would recommend a continuous soffit vent for intake and a continuous ridge vent for the exhaust. There must be an air space between the insulation and roof decking to ensure adequate ventilation between each set of rafters. We also recommend, when possible, that insulation baffles be used between every rafter to ensure proper airflow in the rafter cavity.

In short the answer is yes. If additional exhaust vents are required to balance the overall ventilation system (50% exhaust and 50% intake) we recommend the same vent type be used. Mixing ventilation exhaust systems, gable vents included, is not recommended. When different types of exhaust vents are used, they can draw from one another and increase the likelihood of weather infiltration problems.

A typical reference in answering this question for the US is the International Building Code. The code indications that:

“The minimum required net free ventilating area shall be 1/300 of the area of space ventilated, provided a vapor barrier having a transmission rate not exceeding 1 perm in accordance with ASTM E 96 is installed on the warm side of the attic insulation and provided 50 percent of the required ventilating area are provided by ventilators located in the upper portion of the space to be ventilated at least tree feet (914mm) above the eave or cornice vents, with the balance of the required ventilation provided by eave or cornice vents.” If no vapor barrier is present the ratio is typically 1/150.

In the Canada the guideline comes from the National building code. In general terms it states that:

1) The obstructed vent area shall be not less then 1/300 of the insulated ceiling area.

2) Where the roof slope is less then 2 in 12 or in roofs that are constructed with roof joists, the unobstructed vent area shall be not less than 1/150 of the insulated ceiling area.

3) Required vents may be roof type, eave type, gable-end type or combination there of, and shall be distributed:

a) uniformly on opposite sides of the building

b) with not less than 25% of the required openings located at the top of the space, and

c) with not less than 25% of the required openings located at the bottom of the space.

4) Except where each joist space is separately vented, roof joist spaces shall be interconnected by installing purlins not less than 38 mm by 38mm on the top of the roof joists.

5) Vents shall comply with CAN3-A93-M “Natural Airflow Ventilators for Buildings”

In all cases it is recommended that the local building code and/or officials be consulted to ensure the correct ventilation guidelines are followed.

Typically, building codes will defines attic square footage as the length x the width of the attic floor.

For a balanced ventilation system proper soffit ventilation will need to be installed so that the ridge vent/roof vents may draw in fresh, dry air at the eaves and exhaust warm moist air at the roof peak. If gable vents are present it is recommend that they be closed off after the soffit ventilation is installed. If they are left open the exhaust vent may draw from the gables interrupting the optimal air flow path.

With some building designs the installation of soffit vents is not possible. In this case a roof side intake vent should be reviewed as a possible option.

No, it is recommended that Duraflo Roof vents be installed on a shingle style roof only. Duraflo products are designed and tested with sloped, shingled roof types in mind.

The National Standard of Canada states in Section 3.2 “Insect Protection. Ventilators shall incorporate screens or small louvers designed to keep out most insects. Screens shall not be coarser than 3 mesh per 10 mm. Opening in small louvers without screens shall not exceed 3 x 125 mm.” All of the Duraflo Roof Vents are designed to meet this standard.

Yes, we have a skylight roof vent that is ideal for storage sheds, garages and barns. This product is called our Shed Light Roof Vent and is available in 50 & 75 sq. in. This product will let in natural light.

In general Duraflo roof vents and roof flashing products can be used on a 3/12 to 12/12 roof pitch. Please refer to the specific product sections of Duraflo.com for the pitch range for each product.

Yes, all Duraflo flashings and roof vents have been cold impact tested at -40° to simulate extreme cold weather.

Yes, the Duraflo PermOseal® Multiple Size 3in1 flashing that can be used to fit a 1-1/2”, 2” & 3” pipe Size. Duraflo also manufactures a Stretch Fit flashing that comes in two different sizes, 1-1/2” to 2” and a 3” to 4”, this flashing doesn’t require any cutting, peeling or adjustment.

Yes, we have several colors available for the majority of our roofing products. These colors include Black, Brown, Gray, White, Green & Weatherwood. Please visit our website to see which colors are available for each product.

Please contact our US office at 1-888-461-5307 or our Canadian office at 1-800-461-53001-800-461-5300 to receive information on our warranty policy.

You can contact us in the US at 1-888-461-5307 or in Canadian at 1-800-461-5300 for any other inquires.