Builder’s Technical Sessions - Professional Home Builders
Transcript of Builder’s Technical Sessions - Professional Home Builders
![Page 1: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/1.jpg)
Attic Ventilation
Presented by: Rob Kaethler
Presented in Partnership with:
Builder’s Technical Sessions
Insert your
logo here
![Page 2: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/2.jpg)
Residential VentilationAgenda
Principles of Ventilation
Types of Ventilation
Building Code
Vented and Un-Vented Attics
Balanced Ventilations
Cold Weather roofing
New products and solutions
Trends
![Page 3: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/3.jpg)
Poor Ventilation
![Page 4: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/4.jpg)
Insufficient Ventilation
![Page 5: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/5.jpg)
Adequate Ventilation
![Page 6: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/6.jpg)
Roofing
Manufactures
Require
Ventilation
![Page 7: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/7.jpg)
9.19.1.2 Vent Requirements 1) Except as provided in sentence (2), the unobstructed vent area shall be not
less than 1/300 of the insulated ceiling area
2) Where the roof slope is less then 1 in 6 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 any
combination thereof, 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 is separately vented, roof joists spaces shall be
interconnected by installing purlins not less than 38mm by 38mm on the
top of the roof joists
5) vents shall comply with CAN3-A93-M, “Natural Airflow Ventilators for
Buildings”
![Page 8: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/8.jpg)
Highlights of Building Code
• 1 in 300 rule for normal attics
• 1 in 150 rule for rafter attics
• Uniformly on opposite sides of the roof
• Minimum 25% at or near ridge
• Minimum 25% at or near the bottom
• Meets CSA
![Page 9: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/9.jpg)
Three Strategies for Controlling
Moisture in Roof Assemblies:
• Controlling moisture entry.
• Controlling moisture accumulation.
• Removing moisture that does accumulate by drying.
![Page 10: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/10.jpg)
Un-Vented Roofs
• Un-vented roofs operate on the principle that moisture can be controlled from entering the roof assembly
• The building must have a tight building envelope
• The different parts of a building must be properly pressurized
![Page 11: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/11.jpg)
Un-Vented Roofs
• Building code doesn’t totally allow for it
• Shingle manufactures may not allow for it
• There is no margin of error
• Shingle longevity may be be reduced
![Page 12: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/12.jpg)
Vented Roofs
• Remove moisture from roof cavities
• Control ice damming
• Enhance roofing material life span
• Increase occupant comfort
![Page 13: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/13.jpg)
Vented Roof Assumptions
• The building envelope is tight
• The roof assembly has enough insulation
• Inlet and outlet areas are distributed evenly
• The outside air is able to absorb moisture
![Page 14: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/14.jpg)
Cold Weather Roofing Keys
• Minimize the amount of moisture attic ventilation must deal with
• Use a good vapour retarder
• Reduce air leaks through the ceiling
• Educate home owners about indoor humidity levels during cold weather
![Page 15: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/15.jpg)
The Stack Affect
• Attic air heated by contact with a hot roof on a
warm day tends to rise. This is natural
convection, which pulls cooler air from the soffit
up towards the ridge.
• Natural convection, with a balanced system of
soffit and vents at or near the ridge is the most
effective means of venting the roof.
• The steeper the roof pitch the better the stack
affect works in particularly cold weather
![Page 16: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/16.jpg)
NFA (Net Free Air) or Airflow or
CFM
• NFA is a static measurement;
• Airflow is a dynamic measurement.
• Cubic feet per minute
![Page 17: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/17.jpg)
Balanced Ventilation
• Means for every inch of air exhausted, it must be balanced by providing the same or greater amount of air intake at the eaves or soffits.
Why is balance so important
![Page 18: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/18.jpg)
Balanced Ventilation
![Page 19: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/19.jpg)
Cold Weather Venting
![Page 20: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/20.jpg)
Why Vent an Attic In Cold Weather
• Reduce “ice dams”and “icicle ups”
• Remove moist air from the attic
• Occupant comfort
![Page 21: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/21.jpg)
“Ice Ups” and “The Icing Envelope”
• Snow melts on the roof
• The melt water refreezes
• 22°F or -5.6°C is the magic number
![Page 22: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/22.jpg)
Why We Vent in Cold Weather
“the Icing Envelope”Snow on the roof begins to melt anytime the attic temperatures reaches 30°F(-1.1C), but only refreeze when the outdoor temperature is below 22°F (-5.6C) This is called the “icing envelope” Ice dams could be avoided if attic ventilation could maintain the attic at 30°F or lower when the outdoor temperature was 22°F or lower
Army Core of Engineers
![Page 23: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/23.jpg)
Why we Vent in Cold Weather
Ice Damming
![Page 24: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/24.jpg)
Cold Weather Roofing Keys
The system approach
• Insulation
• Vapour Retarder
• Ventilation
![Page 25: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/25.jpg)
Cold Weather Roofing Keys
Insulation
• A properly insulated home keeps as much of the heat in the house as possible
• Keeps the attic as cold as possible
• Saves money
![Page 26: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/26.jpg)
Cold Weather Roofing Keys
Ventilation
• Balance the ventilation
• What is your air intake?
• What is your air exhaust
• What solution are you using? Why
• Certifications
It is tougher to keep snow out of an attic then rain
![Page 27: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/27.jpg)
Types of Vent Solutions
![Page 28: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/28.jpg)
Potential Vent Options
• Front and back soffit venting
• Gable end vents
• Traditional plastic or metal pot vents
• Ridge vents
• Off peak vents
• Power ventilators
• Wind driven Ventilators
![Page 29: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/29.jpg)
Front and Back Soffit Venting
Slots for Ventilation
Dropped Gabel Truss
![Page 30: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/30.jpg)
Front and Back Soffit Venting
![Page 31: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/31.jpg)
Products and Solutions
• Air intake vents installed low on the roof
![Page 32: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/32.jpg)
Trends
• Solutions to specific application
• Low or no maintenance
• Curb appeal
• Longevity of our roofs
![Page 33: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/33.jpg)
New Products and Solutions
– Off-peak air intake vents
Air Intake Vent
![Page 34: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/34.jpg)
Vents for Special Applications
• Roof meets a wall
![Page 35: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/35.jpg)
New products and solutions
Vents For Hip
![Page 36: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/36.jpg)
New products and solutions
• Vents for specialty applications
– Flexible Vents
![Page 37: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/37.jpg)
Powered Ventilation
![Page 38: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/38.jpg)
Drawbacks of Powered and
Mechanical Ventilators
• If the fan is turned off how much NFA are you getting?
• If it is a mechanical device and it does not function correctly how much NFA are you getting?
• If the air intake doesn’t match the air exhaust where does it get the additional needed air?
![Page 39: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/39.jpg)
Certifications and Standards
• Is it a standard that requires certification or compliance?
• Does the vent have to be modified to meet the standard?
• Is this important?
![Page 40: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/40.jpg)
Miami Dade County• Wind driven rain test 8.8-inches of water at 110 miles per
hour
• Independent NFA Verification
TDI
• Static Pressure Uplift
ICC
Independent NFA Verification
Wind driven snow tests
Dust exposure test
![Page 41: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/41.jpg)
UL and ULC
• Fire Testing
• Code compliance testing
CSA
• CAN3-A93-M
![Page 42: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/42.jpg)
Conclusion
• Reduce the moisture load to the attic from the house
• Make sure you have a balanced system
• Air intake is critical
• Vent for all the weather conditions and all seasons
![Page 43: Builder’s Technical Sessions - Professional Home Builders](https://reader031.fdocuments.net/reader031/viewer/2022020703/61fb2e872e268c58cd5b1f06/html5/thumbnails/43.jpg)
Questions?