GUIDE TO GOOD VENTILATION

Transcription

1 GUIDE TO GOOD VENTILATION Printed in Canada

2 Canplas, the manufacturer of the Duraflo PROventilator, has over 45 years of building materials manufacturing and product innovation experience. Leading edge injection molding technology and high grade UV and cold impact resistant polypropylene are used in the manufacturing process. This approach to manufacturing gives the PROVentilator many unique design features as well as a highly durable dent and corrosion resistant finish. Drawing on a rich history in the ventilation industry the PROVentilator was engineered to provide high performance airflow and weather infiltration protection for the home. The PROVentilator combines the field tested benefits of the patented WeatherPRO internal baffle system with multi stage, high volume, air flow. The superior performance combined with the ease of installation make the PROVentilator the ideal choice for building ventilation. 2

3 Variances & Airflow P. 4 High Performance Airflow P. 6 Net Free Venting P. 7 PROVentilator Venting P. 8 Blocked Soffits P. 9 Soffit Solution P. 10 Structures With No Soffit P. 11 Roofside Intake Venting P. 12 Gable Ventilation P. 13 Mixed Ventilation P. 14 PROVentilator Features P. 15 How It Works P duraflo@canplas.com GD

4 90 Side Angle wind Negative Negative A. Positive Negative Negative B. Positive Negative 90 Front Angle wind Variances & Airflow The main influence in proper attic ventilation is air moving around and through a building (A). When wind hits a building it creates positive pressure on the area blocking its path (B). 4

5 Negative C. Negative Positive 15 Right Angle Wind Positive Negative 5 15 Left Angle Wind Variances & Airflow As air is forced around and over the building areas of negative pressure are created (C). Air movement from areas of positive pressure to areas of negative pressure helps generate the exchange of air in a properly vented attic space.

6 50% Exhaust 130 Sq. In. 25% Soffit 65 Sq. In. 65 Sq. In. 25% Soffit High Performance Ventilation Roof vent exhaust = Soffit vent intake: For optimal performance balancing the intake and exhaust NFVA as much as possible is recommended: 50% in the exhaust openings, 50% in the intake or soffit openings. The National Building Code indicates that no less than 25% of the total ventilation can be in either the intake or exhaust portion of the system. 6

7 40ft 30ft Nation Building Code Requirement: For every 300 square feet of attic floor area 1 square foot of NFVA is required split 50/50 between intake and exhaust Moderate to Steep Slope Roof Attic Floor = 40ft x 27ft = 1080 Sq Ft 1080 Sq Ft 300 Sq Ft = 3.6 Sq Ft total NFVA req d 50% of total NFVA in Exhaust Venting = 1.8 Sq Ft Converted to Sq Inches: 1.8 Sq Ft x 144 Inches = 260 Sq Ins of Exhaust NFVA # of PROVentilators at 130 Sq In NFVA each: 260/130 = 2 Calculating Net Free Venting Requirements A well designed ventilation system is composed of several elements. The most important components are sufficient open venting area or net free venting area (NFVA), in relation to the area of the attic and balance between the air exhaust and air intake components of the system. The National Building Code requires that for every 300 square feet of attic floor space (including soffit overhang) one square foot of ventilation is required. For low sloped roofs it is recommend that this be increased to one square foot of ventilation for every 150 square feet of attic floor space. Note: For the specific ventilation requirements in your area please refer to the national and local building codes. 7

8 Positive Negative Negative The Draw Power of the PROVentilator The principles of positive and negative pressure variances also apply to individual roof vent openings. The air draw created by any roof vent is based largely on how wind (air) moves through and around the vent. When wind hits the vent exterior it creates positive pressure on the surface impacted. As air is forced around and over the vent areas of negative pressure are created. These areas of negative pressure generate exchange of air as air from within the vent and attic rushes out to fill the negative pressure areas. 8

9 Without cooler air entering the soffit helping the heat escape through the roof vents, the air movement in the attic slows and heat builds up in the space. Insulation blocking air from entering through the soffit Common Issue: Soffits blocked with insulation One of the most common and significant issues with a poorly functioning ventilation system is a lack of intake venting. Typically intake venting is located under the eave of a roof with perforated soffit providing the openings. Often insulation and/or building materials extend past the exterior wall of the building and cover the soffit area. 9

10 Rafter vents hold the insulation back allowing room for air to enter the attic space through the soffit. Blocked Soffit Solution: Rafter Vents In a properly functioning ventilation system the intake venting area is free from obstruction allowing fresh, clean air to enter the attic space replacing the exhausted stale air. One of the most effective ways to ensure there is adequate venting area between the insulation and roof decking is with the use of rafter vents. 10

11 Without cooler air entering the soffit helping the heat escape through the roof vents, the air movement in the attic slows and heat builds up in the space. A house with no soffit built into the structure. Common Issue: No Soffit on Structure Depending on the style of the building and the roof design intake venting through the soffit may not be possible. In these situations roof side intake venting is another option. Without adequate intake venting a ventilation system cannot be balanced and will be limited in the amount of air that can be exchanged in the attic space. 11

12 Internal baffles allow for extreme weather protection while allowing for high airflow. PROSlantBack used as an intake vent when no soffit ventilation exists Solution To No Soffit: Roofside Intake Venting One of the main issues with roof side intake venting is the increased possibility for weather infiltration. The WeatherPRO Slantback is a high performance exhaust vent that can also be used in conjunction with the PROVentilator as a solution for roof side intake venting. The PROSlantbacks high degree of weather infiltration protection and attractive low profile appearance make it an ideal choice for an intake application. 12

13 Common issue: Gable Ventilation A common practice in ventilation, especially in older buildings with gable style roofs, is to use gable end venting. This is not typically the optimal form of venting as a full exchange of attic air is not always possible. When using the PROVentilator in combination with gable end vents the air at the eave of the roof many not circulate. The PROVentilator could draw in from the gable vents localizing the air exchange to the upper end sections of the attic space. X Solution: Soffit Venting A better option for a more balanced ventilation system is the use of soffit venting with the PROVentilator. By closing in the gable end venting area and focusing on the soffit areas for intake venting the air exchange is distributed more evenly from peak to eave. 13

14 The large amount of air exiting the PROVentilator creates a large amount of suction from the surrounding area inside the attic. Standard vents positioned to close could become intake vents, limiting air intake from the soffits. Less airflow through soffits allows heat to stay in the lower parts of the attic Common issue? Mixing Exhaust Products Mixing ventilation exhaust products in a single system is not recommended. With the drawing power of the PROVentilator standard vents installed in close proximity can become intake vents disrupting the air exchange in the attic and increasing the possibility of weather infiltration problems. Solution: Similar Exhaust Products If more venting area is required adding additional PROVentilators to balance the exhaust portion of the ventilation system is recommended. Whenever possible all exhaust vents should be evenly spaced across the ridgeline to minimize any intake issues. 14

15 WeatherPRO s patented internal baffles deflect water and snow, allowing moisture to drain harmlessly out of the drainage openings. Designed for high airflow while providing excellent defense against weather infiltration. The PROVentilator s High Performance Airflow The chimney style design allows the PRO Ventilator to harness wind energy and create pressure variances that powerfully draw air out from within the attic space. The PROVentilator s Easy Level features Lightweight, no-assembly design makes for easy handling. Setting the pitch is quick and simple with centralized pivot points, built-in adjustment tabs and pitch stops. Durability: Engineered polypropylene resists denting, crushing, extreme heat and is cold impact resistant to /8 Dimensions: Colours: Black Brown Grey Weatherwood 60PRO150BL 60PRO150BR 60PRO150G 60PRO150WW /8 19-7/8 15

16 Engineered with the contractor in mind. The lightweight, durable construction and rotating pitch adjustment system are designed to simplify the installation process saving you time and money Features: 1. Unique baffle system wards off wind driven snow and rain 2. External Drip tray allows moisture to drain harmlessly away from vent openings 3. Large top cap improves appearance of the roof line 4. Easily adjust to roof pitch with front and back locking tabs 5. Multiple pivot stop points for quick leveling 6. Molded in screw guides help secure vent position quickly and accurately 7. Fully assembled no top and base attachment required on the jobsite Visit.com for complete 3-part master format specifications. 4.