How Whirlybirds Can Help Keep Your Roof BreathingA Roof's Temperature Contributes Significantly to the Life of Your Roof
Whirlybirds Helps Your Roof Breath
A properly vented attic and roof space
How Does Roof Venting Work?
In the heat of the day, the sun’s rays hit your home’s roof and heat the roofing material – this roofing material may be shingles or metal decking, etc.
In any roof material case, this heat then radiates through the roofing material and roof deck (usually plywood) and subsequently heats the air within the attic space. Due to the laws of thermodynamics, this heated attic air rises to the highest point of the attic space seeking an exit. This exit point, or exhaust, can be accomplished by the use of various roof exhaust vent styles including ridge vents, gable vents, or whirlybird wind turbines. The exhaustion of heated attic air only proves beneficial, however, if there is a sufficient cooler air supply provided within the roof ventilation system.
Supply, or intake, air is typically provided via soffit vents located along a home’s eaves. A sufficient supply of cooler, fresh exterior air via soffit vents coupled with the proper exhaust of hotter, stagnant air via ridge vents and/or whirlybirds provides a complete roof ventilation system.
The end goal of any roof venting system in any climate, hot or cold, is to keep the attic space air very near or at the same temperature of the ambient, exterior air. Roof/attic venting works in both winter and summer weather, however, its primary benefits vary depending upon each of these climate conditions.
Roof Venting Benefits
It is a common fear to think that venting your roof within the winter months or within a cold climate is expelling precious, sought-after warm air from your home. Nevertheless, in cold weather climates, the goal of proper ventilation of the attic space is still to keep the attic air cold and similar in temperature to the ambient air. Otherwise, even with sufficient ceiling insulation and airtightness, the heat from your heated living spaces at the lower levels of your home or the sun’s radiation (even in the winter) will migrate into the attic space and warm the roof deck.
This warmth will then allow accumulated snow and ice to melt. This melted snow and ice then drips down to the eaves and gutters and subsequently re-freezes causing ice dams and icicles. Ice dams can wreak havoc on your roofing system and can lead to lifted shingles, damaged gutters, and even water leaking back into your home. Suffice it to say, a properly vented roof system which allows the attic space to stay cold, along with sufficient ceiling insulation within your attic will help minimize ice damming while allowing the living spaces of your home to remain comfortable.
The key to energy efficiency and containing heat within living spaces during winter months or in cold climates within a vented attic home is the addition of insulation within the ceiling deck of the attic space. Too often, a lack of insulation in the ceiling allows a significant amount of heated air into the attic space. This, coupled with poor ventilation, creates a prime environment for melting snow and ice.
Additionally, in cooler weather, moisture may condensate within the attic space if there is a lack of proper air flow. Accumulated moisture over time may generate mold and mildew
In hot weather climates, proper ventilation of the attic space, again, maintains the attic air temperature near that of the exterior, ambient air.
But in a hot weather situation, proper ventilation will allow the hotter, stagnant air generated by the sun’s rays hitting the roof to be properly exhausted and allow cooler, exterior air to take its place.
Without this cycling of air, the energy necessary to keep a home air conditioned is significantly increased. Many times, air conditioning systems are installed with ductwork within the attic space.
Should the attic space become excessively hot, this heat transfer through the ductwork walls will decrease the effectiveness of supplied cool air throughout the home. A combined approach of proper attic ceiling insulation, ductwork insulation, and proper roof venting will drastically improve energy efficiency.
The hot, stagnant air created in a hot weather climate naturally rises and seeks a place to escape.
Static vents such as ridge vents or gables are often chosen to provide exhaust openings for this heat to escape, but they can often be under-sized for the air volume and application.
Whirlybirds, however, can provide added air exhaust volume capability, thereby allowing a larger volume of cool, fresh air into the attic space in far less time than a natural air flow process.
How to Properly Vent a Roof
So how does one properly vent their roof to achieve these benefits? Typically, local and regional building codes dictate the proper venting requirements for any particular area and climate. However, most homes contain improper ventilation and could use a ventilation boost. As previously mentioned, proper ventilation is a system – air intake and air exhaust.
Intake vents are found in the form of static soffit vents that are found under the eaves of your home and are often spaced every 2 or 3 meters under the eaves, depending on your home’s attic size. Exhaust venting can be achieved via static venting at the ridge, or apex, of a home’s roof or at the roof gables. Static exhaust venting relies on the natural tendency for heat to rise.
This can be problematic; however, as ridge ventilation alone often does not provide enough air ventilation and can be supplemented by the use of active turbine exhaust vents, or whirlybirds. The addition of whirlybirds adds a new dynamic to the expulsion of air from an attic space. Most whirlybirds use wind power to assist with more rapid air removal.
Even with a slight breeze, a wind-powered whirlybird can begin to spin quickly. The spinning of the whirlybird fins (or turbines) creates a vacuum that sucks the air out of the attic space at a higher volume over time than that of a static ridge or gable vent. The result is a significant increase in air turnover within an attic space, thereby allowing increased venting and increased venting benefits.
Proper ventilation, however, requires a balance in both exhaust and intake air flow. A proper balance will allow continuous movement of air with no “bottlenecks” in the system. A lack of supply (intake) air will cause negative pressure and seek to pull air from areas with poor seals between conditioned living spaces and the attic space. A lack of air exhaust will cause stagnancy and increased heat and moisture build-up which exacerbates the problems mentioned previously.
Depending upon your regional climate, a typical building code will recommend the amount of attic ventilation by way of a ratio between square meters of enclosed attic space to square meters of ventilation required. Once the square meters of ventilation required is known, a properly balanced system is created by splitting that ventilation value between intake ventilation features (soffit vents) and exhaust ventilation features (ridge vents or whirlybirds). Each ventilation product available should provide the equivalent ventilation area applicable to a single unit.
This is also called the Net Free Area (NFA). For example, to determine how many whirlybirds are needed for exhaust ventilation, divide the total square meters of exhaust ventilation calculated above by the NFA information provided by the whirlybird manufacturer. This will provide you with the approximate count of whirlybirds necessary for your particular roof/attic ventilation system.
Mostly near the roof ridge for better functioning. Depending on the size of your budget or the climatic conditions you are against, you can choose the most suited roof air vents for your house.
• Intake Vents
Intake vents are not very easy to spot because they are not installed on the roof. They are mainly located at the edge of roofs, under the shingles or at the drip edge. Most intake vents are made of copolymer material.
The primary purpose of intake vents is to allow cold, low-pressure air to enter the attic and force the hot air to leave through the exhaust vents. This continuous process is what provides the cooling effect on the roof and the attic.
Whirlybird Installation Guide
In addition to being cost-effective, efficient ventilators, whirlybirds are a good choice for do-it-yourself homeowners looking to increase roofing exhaust ventilation due to their relative ease of installation. Most residential whirlybirds can be simply mounted to a plywood roof deck with minimal tools and know-how.
In general, a whirlybird consists of a sheet metal aluminum or galvanized steel flashed base unit that is secured to the roof deck with roofing nails and further caulked for water tightness. (Note: The following is merely a general guide to installing a standard wind-powered whirlybird on a shingled roof.
Be sure to follow the installation instructions of your particular whirlybird manufacturer for a proper installation.) If your roof is pitched, it will be necessary to determine the roof pitch angle so that the whirlybird elbow can be situated such that the whirlybird turbines are perfectly vertical for proper, free spinning operation.
Be sure to confirm your pitch can be accommodated by the whirlybird unit of your choice, as some very steep roof pitches may not be accommodated.
Once the base elbow angle is determined and confirmed, layout the whirlybird base on the roof in the location desired and mark the opening to be cut on the shingles. Be sure to situate the whirlybird near the apex of the roof so that it can be exposed to all wind directions. If you are installing a solar-powered whirlybird, position the unit at the apex of the roof, but also in an area that receives plenty of sunlight throughout the day.
Also, be sure to layout your whirlybird between rafters, as straddling a rafter (though it can be done) will cause a decrease in airflow efficiency. Truthfully, the hardest part of the installation is getting the confidence to cut a hole in your perfectly watertight roof. Have no fear, though, because once the whirlybird is installed and the base caulked, they provide watertight service due to their fin design.
After cutting the hole in the shingles and roof deck, position the whirlybird base under the upper layer of shingles and nail in place. Next, using a quality roofing sealant/cement, seal all nail heads, seams, and flashing connections to ensure a watertight base installation to the roof deck. Lastly, simply install the turbine per your manufacturer’s installation instructions and ensure the turbine spins without issue. You now can enjoy your improved roof and attic exhaust ventilation capabilities.
Whirlybird Maintenance and Tips
Whirlybirds are relatively maintenance free; however, several common-sense tips should be employed: First, be sure to keep the whirlybird turbines and base free from buildup of leaves, sticks, pine needles, etc. which could inhibit the rotating turbines and gum up the bearings as well as encourage pooling of water around the base. Second, despite what some may tell you, do not plug your whirlybird vent with insulation in winter months. As we explored previously, the benefits of
Plugging the whirlybird in the winter months only serves to short-circuit your newly improved ventilation capabilities. Third, some whirlybird models may require that you periodically lubricate the bearings on which the turbines turn. Check your manufacturer’s requirements, and ensure this maintenance gets performed as recommended to minimize noise and inefficient operation. Lastly, periodically ensure water tightness around caulked joints and nail holes. Even the best roof sealants and types of cement degrade over time and need the occasional boost.
If installing multiple whirlybirds on your roof, be sure to align them all at the same level along the roof ridgeline. This ensures that all whirlybirds pull air from the lower intake vents at the soffit, rather than pulling air from lower, improperly located whirlybirds. Remember that proper attic ventilation is a dual system of intake and exhaust ventilation.
Therefore, an increase in exhaust ventilation without an equal increase in intake ventilation will not achieve the results and benefits you are after. If you are in doubt of your ventilation needs, it may be best to consult a builder or architect to review your local codes requirements and your home’s current ventilation system.
It is important to remember that proper attic and roof venting should be combined with additional measures to properly insulate and air-seal your home as a whole. Attic insulation for vented attic homes should be layered above the ceiling and at a proper R-value based on the region in which you live. If possible, your attic should also be free of obstructions, including HVAC units, ductwork, and even storage.
This may sound undesirable, but obstructions such as these hinder proper air flow from lower intake soffit ventilators to upper exhaust ventilators like whirlybirds. This multi-faceted home improvement approach will lead to even larger gains in energy efficiency and temperature control than singular approaches of additional ventilation.