Ventilation Frequently Asked Questions
- Where does the moisture that affects an attic come from?
- Can I over ventilate my attic?
- What is net free area (NFA)?
- What is the difference between an intake and exhaust vent?
- What products do you manufacture?
- Which exhaust ventilation product is most effective?
- How does a ventilator’s design make a difference in its long term effectiveness?
- What are your product warranties?
- How do I obtain warranty service?
- My warranty has expired, can I purchase replacement parts?
- How do I choose a proper sized ventilation system?
- How difficult is it to install a ventilator?
- What role do insulation baffles play in a ventilation system?
- What is the best way to ventilate an attic with a "kneewall."?
- How does roof line design affect a ventilation system?
- Are aluminum or vinyl soffit panel systems good sources of intake ventilation?
- Can I add ventilation to my existing system?
- Should I cover my turbines in the winter?
- Where are Lomanco’s products produced?
- Where can I purchase Lomanco products?
Where does the moisture that affects an attic come from? (Back)
Houses are built much "tighter" today than they were 20 or 30 years ago. Windows are more efficient, house wraps are now commonly used, the R value of insulation has increased. Overall, our homes are more weather-tight. In doing this we trap the moisture in the home. Indoor moisture is generated by many things. The normal perspiration and breathing of a family of four adds about ½ pint of water to the air every hour. Cooking three meals a day adds four or five pints of water to the air. Each shower contributes ½ pint. In fact, every activity that uses water, (like dishwashing, mopping floors, doing laundry) adds moisture to the air. Experts say 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. Air moisture will flow toward drier air to equalize itself. This equalization process actually forces the indoor moisture through the ceiling and insulation into the attic area.
In attics which are not properly vented, moisture is also created by simple condensation. The air inside an improperly vented attic will be warmer than the air outside. When this warmer, moist air comes in contact with the colder roof sheathing condensation will occur. In effect, it can actually "rain" in your attic.
Can I over ventilate my attic? (Back)
The ideal ventilation system maintains the same temperature in your attic as outside or at least within 10 degrees. Minimum property standards and codes where developed in 1948. These codes were set as minimums based solely on the attic floor space. Due to the many variables in construction (roof pitches, roof color, ceiling designs), you may need to increase the amount of ventilation. Also, minimum standards may not provide an equality between intake and exhaust ventilation. Just remember if you increase the amount of exhaust ventilation – you must have an equal amount of intake. If either part of the system is unbalanced, it is better to have more intake.
What is net free area (NFA)? (Back)
Net free area is the standard of measurement used by our industry. It is the unobstructed area of a ventilator through which air may flow. For an example, a C816 cornice vent is a 16x8 vent. The hole cut for this vent would be approximately 15 inches long by 7 inches wide. The area of the opening would be 105 (7x15) square inches but the net free area of a Lomanco C816 is 65 square inches. The louvered section and screening hinder the air flow and their net free area is lessened by their measurements.
What is the difference between an intake and exhaust vent? (Back)
The most important difference in an intake and exhaust vent is their location on the roof. All exhaust type ventilators 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.
Note: Sometimes, due to the lack of overhang-under-eave area, roof louvers are installed low on the roof and used as intake. We DO NOT recommend this due to the possibility of weather infiltration.
What products do you manufacture? (Back)
We manufacture a complete line of residential or light commercial attic and crawlspace ventilation products. Our products fall into seven categories: Turbine Ventilators, Roof Vents, Power Ventilators, Ridge Vents, Gable Vents, Intake Vents, and Foundations Vents.
Which exhaust ventilation product is most effective? (Back)
Ventilation products are part of a system of intake and exhaust ventilators. As long as the proper number of vents are used and the system is balanced, (50% exhaust and 50% intake), ridge vents, roof louvers, whirlybirds, power ventilators or gables will be equally effective. However, the design of the product does make a difference in it's long term effectiveness.
How does a ventilator’s design make a difference in it's long term effectiveness? (Back)
We incorporate the "Lomanco Balance", which simply means you get the maximum ventilating capacity and the best weather protection available. Let’s examine how this is achieved:
- Ridge Vents: For a ridge vent to work it must have an exterior baffle. Once the wind hits the baffle it will create a low-pressure area around the ridge vent and pull air from the attic. Lomanco’s Omni Ridge shingle over ridge incorporates an exterior baffle the full length of the ridge vent plus patented Omni baffles utilizes the winds when parallel to ridge vent.
- Whirlybirds®: Any ventilator with moving parts must provide longevity. The Whirlybird® turbine ventilator is a prime example of a well designed/ engineered product. It’s dual ball bearing system and weight load distribution enables Lomanco to offer a Forever Guarantee transferable from homeowner to homeowner. Remember if a turbine is not turning it is not working!!
- Intake Vents: Lomanco’s under-eave vents incorporate an "eyebrow" designed opening to insure the ventilator can not be crushed down and the ventilator capacity closed off.
- Roof Louvers: The Lomanco 750 is engineered with a tall collar or stack. A ventilator is a lot like a chimney. The higher the stack the better the draw. If you lower the stack – you get down drafts. Cubic Foot per Minute testing has proven the 750 superior to other 50 square inch vents on the market. In addition to its capacity to ventilate, the 750 will not leave those unsightly discoloration circles on your shingles.
- Power Ventilators: The LomanCool 2000H comes complete with a built in thermostat and humidistat. Most power vents on the market today are equipped with thermostats and only operate when temperatures in your attic reach approximately 100 degrees. Since attic ventilation is required year around, a humidistat must be installed to activate the unit based on excessive moisture being present in the attic area.
- Gable Ventilators: We use more metal (aluminum) when manufacturing our 900 series adjustable triangular gable vents. This allows us to have a wider pivoting blade for better weather protection. Even though we may have the same number of blades as a competitor, our frame length will be longer thus providing you more net free area of ventilation capacity.
- Foundation Vents: The aluminum construction of our most popular model, 179, provides a workable unit at all times. Aluminum will not rust. Some other foundation vents on the market use galvanized steel with raw edges. Once the rust forms the unit becomes stationary, and unfortunately it is usually rusted in the closed position, robbing your home of its protective air movement.
What are your product warranties? (Back)
Product warranties vary by type of product – please choose the appropriate product for warranty details:
Turbines, Roof Louvers, Power Vents, Ridge Vents, Gable Vents, Intake Vents, Foundation Vents
How do I obtain warranty service? (Back)
The fastest way to receive service is by contacting the dealer from which the product was obtained. If you are unsure, please contact our customer service department at 1-800-643-5596. Please refer to the warranties listed above for specifics.
My warranty has expired, can I purchase replacement parts? (Back)
Replacement parts for power ventilators are available for units manufactured in 1976 or after. These can be obtained either through your local supplier or by calling our customer service department at 1-800-643-5596. The quickest and easiest way to purchase power ventilator replacement parts is to use our online store.
How do I choose a proper sized ventilation system? (Back)
Local roofing professionals and supply houses can assist you in determining the best ventilation system for your home. Lomanco provides slide rules and charts to help them determine the ventilation necessary to meet minimum property standards. By meeting this minimum standard you will meet local building codes, (U.B.C.; CABO; BOCA; SBCCI; CSA; etc.) and fulfill the warranty requirements on major building components such as shingles and insulation. The Lomanco Selector Guide chart is also provided at this site.
How difficult is it to install a ventilator? (Back)
Most consumers choose to have their ventilation system installed by a professional – cutting a hole in a roof can be intimidating to say the least. However, step by step instructions are provided for your reference.
What role do insulation baffles play in a ventilation system? (Back)
Insulation baffles (proper vents, vent chutes) are a major factor in insuring your intake ventilators are functioning. These baffles are placed in between the rafters in your attic to provide an air space between the intake and exhaust ventilators. We recommend you use a baffle in every rafter tail area when using continuous soffit vent . If baffles are not used, make sure that the insulation is pulled back away from the soffit vents.
What is the best way to ventilate an attic with a "kneewall."? (Back)
A kneewall exists when a room is built within the attic cavity. The lower attic area is separated from the upper attic area. Lomanco recommends the insulation baffles be used between every rafter where the ceiling of the kneewall meets the sloped rafters. This will facilitate a system of intake to the exhaust vents located in the upper portion of the attic.
How does roof line design effect a ventilation system? (Back)
Today’s roof scapes are very diverse; hips, gables, dormers, and other variances. These variances are crucial in determining the type of ventilation required. For example:
Hip roof designs sometimes have short ridge runs (less than 20 feet). Ridge vents installed on this ridge would not provide the proper net free area required. Lomanco would recommend; Whirlybirds®, power ventilators, or roof louvers be used.
Multiple gables also present ventilation dilemmas. Gables take away from the amount of under-eave-overhang area of a home. This area must provide for the under-eave or intake ventilation. Remember intake ventilation must be 50% of the ventilation system.
Intake ventilation should be provided on dormers too. Exhaust ventilation for the dormer attic area can be provided by the main upper roofline to meet minimum property standards. If the dormer has a cathedral ceiling it must be vented with a ridge vent type product for exhaust. If the dormer has an attic space sealed off from the main attic area, then it must be treated as a separate attic.(explain further)
Homes with little or no overhang present a problem when providing the intake part of the system. Lomanco would recommend a SV-10 be used. It is a drip edge and continuous soffit combination. Lomanco does not recommend using conventional roof louvers installed on the lower part of the roof for intake.
What is the best way to ventilate a cathedral or vaulted ceiling? (Back)
On a true cathedral ceiling, which has an air space between the insulation and roof decking of at least 2 inches – we would recommend a continuous soffit vent for intake and a continuous ridge vent for the exhaust. This will insure ventilation between each set of rafters.
Are aluminum or vinyl soffit panel systems good sources of intake ventilation? (Back)
We recommend fully vented panels be used continuously around the soffit area to maximize intake ventilation. Check with the manufacturer of the panel for net free area ratings. Remember, intake is 50% of the system. It is very important to insure the intake net free area is balanced with the net free area of the exhaust ventilators.
Can I add ventilation to my existing system? (Back)
Yes. We recommend if you add additional exhaust vents to use the same type. If Whirlybirds® exist, add Whirlybirds®, if roof louvers exist, add roof louvers. We do not recommend mixing exhaust systems. Exhaust vents look for intake from the path of least resistance. When different types of exhaust vents are used, they tend to pull from one another and can cause weather infiltration problems. Remember gable vents are exhaust vents. Also, do not overlook the intake part of the system. A balanced system has 50% exhaust and 50% intake.
Should I cover my turbines in the winter? (Back)
Attic ventilation systems are required year around. Most people associate attic ventilation with heat; however, of the two major destructive forces at work in your attic, moisture, not heat, is the most destructive. Since winter air is drier, it absorbs moisture from your home and you. The attic space is even more susceptible to excessive moisture in the winter. Plus when air is trapped inside the attic – it will always be warmer than the air outside. The roof sheathing/decking will be colder in winter months. Thus creating even more condensation. It can literally "rain" in your attic. This moisture produces mildew, rotting conditions damaging wood members and destroying shingles or it drips down to the ceiling below to damage plaster or paint. Insulation also becomes wet and provides less resistance to heat loss – in effect loses its R-value.
Where are Lomanco’s product produced? (Back)
Lomanco’s corporate offices and main manufacturing facility is centrally located in Jacksonville, Arkansas. We also have a plant in Kingman, Arizona to better serve our West Coast distribution network. Additionally, we have manufacturing partners located in Australia, Asia, and Africa.
Where can I purchase Lomanco products? (Back)
We distribute our products throughout in the United States, as well as Canada, Mexico, South America, Europe, Africa, Australia and Asia. Lomanco products can be found in most lumberyards, roofing supply houses and building material retailers throughout the U.S. and Canada. Internationally, our products are distributed through manufacturing partners and various suppliers. If Lomanco products are not available at your local supplier, please call 1-800-643-5596 or Email us at lmcwebmail@lomanco.com for a supplier in your area.
Our distribution network includes area market managers throughout the United States who may also provide assistance in locating our product.