Ventilation Calculator

How to Calculate

Step 1: Measure

Measure the length and width of the attic floor space to be ventilated.

Step 2: Calculate

Enter the length and width or the total square footage of the attic floor space to be ventilated.
Check Mark in Badge Icon

Step 3: Identify

See recommended quantities below for each GAF Ventilation Product (typically rounded up).

Let’s get started

Use this calculator to help determine the proper amount of attic ventilation based on U.S. FHA 1/300 guidelines.*

Please choose an address from the list or your address won’t be submitted.
Enter your measurements below.
Please enter a valid number
Please enter a valid number

Or

Please enter a valid number

Suggestions for 900 sq. ft. Area

Numbers shown represent the recommended total number of units required for a single product.
384 Minimum Sq. In. of Net Free Area of exhaust needed at or near the ridge.
And
384 Minimum Sq. In. of Net Free Area of intake needed at or near the soffit.

Please Note:

Some local building codes require the 1/150 attic ventilation rule, which increases the minimum attic ventilation needed. Always consult local building code requirements in your area for details.
Note: N/R = not recommended

Exhaust Ventilation

ProductLineal Feet Required
Cobra® RidgeRunner®31'
Cobra® Rigid Vent 322'
Cobra® SnowCountry®22'
Cobra® SnowCountry® Advanced22'
Cobra® Hip Vent43'
TruSlate® Ridge Vent43'

Product

Cobra® RidgeRunner®

Lineal Feet Required

31'

Product

Cobra® Rigid Vent 3

Lineal Feet Required

22'

Product

Cobra® SnowCountry®

Lineal Feet Required

22'

Product

Cobra® SnowCountry® Advanced

Lineal Feet Required

22'

Product

Cobra® Hip Vent

Lineal Feet Required

22'

Product

TruSlate® Ridge Vent

Lineal Feet Required

22'

ProductLineal Feet Required
Cobra® Exhaust Vent - Hand Nailable31'
Cobra® Exhaust Vent - Nail Gunnable22'

Product

Cobra® Exhaust Vent - Hand Nailable

Lineal Feet Required

31'

Product

Cobra® Exhaust Vent - Nail Gunnable

Lineal Feet Required

22'

ProductLineal Feet Required
AR1031'

Product

AR10

Lineal Feet Required

31'

ProductNumber Required
RT65 Plastic Square - Top31
IR61 Plastic Slant - Back31
R50/RV50 Metal Utility31
IR65 Plastic Slant - Back31
SSB960 Metal Super Slant - Back31
HCD144 High-Capacity Dome Vent31

Product

RT65 Plastic Square - Top

Number Required

31

Product

IR61 Plastic Slant - Back

Number Required

31

Product

R50/RV50 Metal Utility

Number Required

31

Product

IR65 Plastic Slant - Back

Number Required

31

Product

SSB960 Metal Super Slant - Back

Number Required

31

Product

HCD144 High-Capacity Dome Vent

Number Required

31

Intake Ventilation

ProductLineal Feet Required
Cobra IntakePro®31'

Product

Cobra IntakePro®

Lineal Feet Required

31'

Product

Cobra® Fascia Vent (Mesh Roll) 1"

Lineal Feet Required

22'

Product

Cobra® Fascia Vent (Mesh Roll) 1.5"

Lineal Feet Required

22'

ProductNumber Required
LSV8 Metal Continuous Soffit Vents (Lineal Feet)31'
EAP 4x12 Plastic Soffit Vents31
EAC 16x4 Metal Soffit Vents31
EAC 16x8 Metal Soffit Vents31
EmberShield® Closeable Soffit Vents31

Product

LSV8 Metal Continuous Soffit Vents

Number Required

31

Product

EAP 4x12 Plastic Soffit Vents

Number Required

22

Product

EAC 16x4 Metal Soffit Vents

Number Required

22

Product

EAC 16x8 Metal Soffit Vents

Number Required

22

Product

EmberShield® Closeable Soffit Vents

Number Required

22

Intake or Exhaust Ventilation

Note: Gable louvers are typically installed in pairs

ProductNumber Required
DA 12x1231
DA 12x1831
DA 14x2431
DA 18x2431
DA 24x3031

Product

DA 12x12

Number Required

31

Product

DA 12x18

Number Required

31

Product

DA 14x24

Number Required

31

Product

DA 18x24

Number Required

32

Product

DA 24x30

Number Required

33

ProductNumber Required
SL 8x831
SL 12x1231
SL 12x1831
SL 18x2431

Product

SL 8x8

Number Required

34

Product

SL 12x12

Number Required

35

Product

SL 12x18

Number Required

36

Product

SL 14x24

Number Required

37

Product

SL 18x24

Number Required

38

ProductNumber Required
RLSC 2"31
RLSC 3"31
RLSC 4"31

Product

RLSC 2"

Number Required

39

Product

RLSC 3"

Number Required

40

Product

RLSC 4"

Number Required

41

Exhaust Ventilation

ProductNumber Required
ERV431
ERV5 & Wi-Fi ERV5QCT22
ERV622
EZ Cool EZCR122

Product

ERV4

Number Required

31

Product

ERV5 & Wi-Fi ERV5QCT

Number Required

22

Product

ERV6

Number Required

31

Product

EZ Cool EZCR1

Number Required

31

ProductNumber Required
EGV5 & Wi-Fi EGV5QCT31
EGV622
EZ Cool EZCG122

Product

EGV5 & Wi-Fi EGV5QCT

Number Required

31

Product

EGV6

Number Required

31

Product

EZ Cool EZCG1

Number Required

31

ProductNumber Required
Solar & Dual-Powered Roof (ERVSOLAR / ERVHYBRID)31
Solar-Powered Gable (PGSOLAR)22
High-Power Solar & Dual-Powered Roof (PRSOLAR2 / PRHYBRID2)22

Product

Solar & Dual-Powered Roof (ERVSOLAR / ERVHYBRID)

Number Required

31

Product

Solar-Powered Gable (PGSOLAR)

Number Required

31

Product

High-Power Solar & Dual-Powered Roof (PRSOLAR2 / PRHYBRID2)

Number Required

31

ProductNumber Required
12"31
14"22

Product

12"

Number Required

31

Product

14"

Number Required

31

Intake Ventilation

ProductLineal Feet Required
with ERV431'
with ERV5 & Wi-Fi ERV5QCT22'
with ERV631'
with EZ Cool EZCR131'
with EGV5 & Wi-Fi EGV5QCT22'
with EGV631'
with EZ Cool EZCG131'
with Solar & Dual-Powered Roof22'
with Solar-Powered Gable22'
with High-Power Solar & Dual-Powered Roof22'
with 12" Wind Turbine22'
with 14" Wind Turbine22'

Product

with ERV4

Lineal Feet Required

31'

Product

with ERV5 & Wi-Fi ERV5QCT

Lineal Feet Required

31'

Product

with ERV6

Lineal Feet Required

31'

Product

with EZ Cool EZCR1

Lineal Feet Required

31'

Product

with EGV5 & Wi-Fi EGV5QCT

Lineal Feet Required

31'

Product

with EGV6

Lineal Feet Required

31'

Product

with EZ Cool EZCG1

Lineal Feet Required

31'

Product

with Solar & Dual-Powered Roof

Lineal Feet Required

31'

Product

with Solar-Powered Gable

Lineal Feet Required

31'

Product

with High-Power Solar & Dual-Powered Roof

Lineal Feet Required

31'

Product

with 12" Wind Turbine

Lineal Feet Required

31'

Product

with 14" Wind Turbine

Lineal Feet Required

31'

ProductLineal Feet Required
with ERV431'
with ERV5 & Wi-Fi ERV5QCT22'
with ERV631'
with EZ Cool EZCR131'
with EGV5 & Wi-Fi EGV5QCT22'
with EGV631'
with EZ Cool EZCG131'
with Solar & Dual-Powered Roof22'
with Solar-Powered Gable22'
with High-Power Solar & Dual-Powered Roof22'
with 12" Wind Turbine22'
with 14" Wind Turbine22'

Product

with ERV4

Lineal Feet Required

31'

Product

with ERV5 & Wi-Fi ERV5QCT

Lineal Feet Required

31'

Product

with ERV6

Lineal Feet Required

31'

Product

with EZ Cool EZCR1

Lineal Feet Required

31'

Product

with EGV5 & Wi-Fi EGV5QCT

Lineal Feet Required

31'

Product

with EGV6

Lineal Feet Required

31'

Product

with EZ Cool EZCG1

Lineal Feet Required

31'

Product

with Solar & Dual-Powered Roof

Lineal Feet Required

31'

Product

with Solar-Powered Gable

Lineal Feet Required

40'

Product

with High-Power Solar & Dual-Powered Roof

Lineal Feet Required

31'

Product

with 12" Wind Turbine

Lineal Feet Required

31'

Product

with 14" Wind Turbine

Lineal Feet Required

31'

ProductNumber Required
with ERV431
with ERV5 & Wi-Fi ERV5QCT22
with ERV631
with EZ Cool EZCR131
with EGV5 & Wi-Fi EGV5QCT22
with EGV631
with EZ Cool EZCG131
with Solar & Dual-Powered Roof22
with Solar-Powered Gable22
with High-Power Solar & Dual-Powered Roof22
with 12" Wind Turbine22
with 14" Wind Turbine22

Product

with ERV4

Number Required

31

Product

with ERV5 & Wi-Fi ERV5QCT

Number Required

31

Product

with ERV6

Number Required

31

Product

with EZ Cool EZCR1

Number Required

31

Product

with EGV5 & Wi-Fi EGV5QCT

Number Required

31

Product

with EGV6

Number Required

31

Product

with EZ Cool EZCG1

Number Required

31

Product

with Solar & Dual-Powered Roof

Number Required

31

Product

with Solar-Powered Gable

Number Required

49

Product

with High-Power Solar & Dual-Powered Roof

Number Required

31

Product

with 12" Wind Turbine

Number Required

31

Product

with 14" Wind Turbine

Number Required

31

ProductNumber Required
with ERV431
with ERV5 & Wi-Fi ERV5QCT22
with ERV631
with EZ Cool EZCR131
with EGV5 & Wi-Fi EGV5QCT22
with EGV631
with EZ Cool EZCG131
with Solar & Dual-Powered Roof22
with Solar-Powered Gable22
with High-Power Solar & Dual-Powered Roof22
with 12" Wind Turbine22
with 14" Wind Turbine22

Product

with ERV4

Number Required

31

Product

with ERV5 & Wi-Fi ERV5QCT

Number Required

31

Product

with ERV6

Number Required

31

Product

with EZ Cool EZCR1

Number Required

31

Product

with EGV5 & Wi-Fi EGV5QCT

Number Required

31

Product

with EGV6

Number Required

31

Product

with EZ Cool EZCG1

Number Required

31

Product

with Solar & Dual-Powered Roof

Number Required

31

Product

with Solar-Powered Gable

Number Required

58

Product

with High-Power Solar & Dual-Powered Roof

Number Required

31

Product

with 12" Wind Turbine

Number Required

31

Product

with 14" Wind Turbine

Number Required

31

ProductNumber Required
with ERV431
with ERV5 & Wi-Fi ERV5QCT22
with ERV631
with EZ Cool EZCR131
with EGV5 & Wi-Fi EGV5QCT22
with EGV631
with EZ Cool EZCG131
with Solar & Dual-Powered Roof22
with Solar-Powered Gable22
with High-Power Solar & Dual-Powered Roof22
with 12" Wind Turbine22
with 14" Wind Turbine22

Product

with ERV4

Number Required

31

Product

with ERV5 & Wi-Fi ERV5QCT

Number Required

31

with ERV6

Number Required

31

with EZ Cool EZCR1

Number Required

31

with EGV5 & Wi-Fi EGV5QCT

Number Required

31

with EZ Cool EZCG1

Number Required

31

with Solar & Dual-Powered Roof

Number Required

31

with Solar-Powered Gable

Number Required

67

with High-Power Solar & Dual-Powered Roof

Number Required

31

with 12" Wind Turbine

Number Required

31

with 14" Wind Turbine

Number Required

31

ProductNumber Required
with ERV431
with ERV5 & Wi-Fi ERV5QCT22
with ERV631
with EZ Cool EZCR131
with EGV5 & Wi-Fi EGV5QCT22
with EGV631
with EZ Cool EZCG131
with Solar & Dual-Powered Roof22
with Solar-Powered Gable22
with High-Power Solar & Dual-Powered Roof22
with 12" Wind Turbine22
with 14" Wind Turbine22

Product

with ERV4

Number Required

31

Product

with ERV5 & Wi-Fi ERV5QCT

Number Required

31

Product

with ERV6

Number Required

31

Product

with EZ Cool EZCR1

Number Required

31

Product

with EGV5 & Wi-Fi EGV5QCT

Number Required

31

Product

with EGV6

Number Required

31

Product

with EZ Cool EZCG1

Number Required

31

Product

with Solar & Dual-Powered Roof

Number Required

31

Product

with Solar-Powered Gable

Number Required

75

Product

with High-Power Solar & Dual-Powered Roof

Number Required

31

Product

with 12" Wind Turbine

Number Required

31

Product

with 14" Wind Turbine

Number Required

31

Diagram of intake and exhaust ventilation

The 1/300 balanced attic ventilation rule

Proper attic ventilation consists of a balance between air intake (at or near your soffits) and air exhaust (at or near your roof ridge). The U.S. Federal Housing authority recommends a minimum of 1 square foot of attic ventilation (evenly split between intake and exhaust) for every 300 square feet of attic floor space. Always have a balanced ventilation system. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.
*Note: The 1/300 rule is a general rule and does not apply to all situations. Local building codes, when stricter, take precedence. Always consult a design professional for cathedral ceilings, insulated roof decks, etc.
Examples of static, power, and mechanical attic vents

Learn about attic vent options

Are you confused about the many attic ventilation solutions available? Curious why one roof would get ridge ventilation and another would incorporate power vents or a roof louver? Watch this video for a great introduction to the art and science of choosing the right attic ventilation components for your roof.

Your top attic ventilation questions answered

Image showing why you should use attic ventilation

How to Ventilate an Attic - How Attic Ventilation Works | GAF Roofing

What is attic ventilation? Learn how attics are ventilated.

How to Select Products for Your Attic Ventilation System | GAF Roofing

Determine which ventilation products are best for your roofing project.

How to Plan a Balanced Attic Ventilation System | GAF Roofing Materials

In this video, you will learn how to calculate a balanced attic ventilation system.

How to Avoid Common Attic Ventilation Installation Mistakes | GAF Roofing

When planning and installing a balanced attic ventilation system, it is important to understand and avoid these common mistakes that may reduce the effectiveness of the system.

Related Articles

Roofer climbing a ladder leaning against the roof of a house.
Residential Roofing

What Are Ladder Hooks?

As a roofing contractor, keeping yourself and your employees safe is crucial, which involves using the right equipment. Ladder hooks, sometimes referred to as roof hooks, are used to secure a ladder over the top of a roof's ridgeline. They're an essential piece of safety equipment for steep-slope roofing work.How Do Ladder Hooks Work?These hooks resemble a shepherd's crook that hooks over the roof's ridgeline and stays put with an attached T-bar to secure it to the other side of the ridge. The bottom of the crook has a smaller hook that holds the ladder and prevents it from slipping or sliding down the roof. Ladder hooks are typically made from heavy-duty steel and can support several hundred pounds. They essentially turn the ladder into a more stable set of stairs, creating a safer and more efficient work environment for roofing professionals, especially during steep-slope work.Most hooks also feature a rubber wheel that can help you get the ladder safely up onto the roof. Once you secure the hook on the rungs of the ladder, roll the ladder up the slope (on its back). When it passes the roof ridgeline, flip the ladder over to secure the hooks over the top of the ridgeline.Why Should You Use a Ladder Hook?According to the American Ladder Institute, 500,000 people are treated for injuries from using ladders every year, with 300 of those injuries leading to fatalities. With newer home styles featuring more dramatic rooflines with steep pitches, you may find yourself facing 10:12, 12:12, and higher pitches more regularly. Ladder hooks can help make working on these roofs safer.They can provide stability and security on lower-pitched roofs, too. You may also want to use them for performing repairs around skylights or chimneys, especially if the roof surface is icy or slippery. And they can provide secure footing in cases of suspected damage, such as a weak or rotting deck.These safety devices are designed to prevent the ladder from damaging shingles, so there's no downside to using them.Can a Ladder Hook Replace Other Safety Measures?Using a ladder hook can make you feel more secure and stable on a steep pitch. But you shouldn't forego other safety measures, such as using a personal fall arrest system consisting of lifelines, lanyards, and deceleration devices attached to an anchor point and connected to the body harness. Remember, the anchorage should be able to support 5,000 pounds per employee. Ladder hooks are designed to secure the ladder to the rooftop—not to secure a person or prevent them from falling.How Do You Choose the Right Ladder Hook?To find the right ladder hook, contact your ladder's manufacturer to see if it has a hook designed to work with its ladders. If it doesn't offer any, review the ladder hook manufacturer's guidelines to see what types of ladders are best suited for its hook. If your ladders are due for replacement, you can also look for manufacturers that offer kits with both the ladder and the hook.For more learning opportunities and resources to help you succeed in your roofing business, visit the GAF Center for the Advancement of Roofing Excellence (CARE).

By Authors Karen L Edwards

March 18, 2024

Contractor installing a residential roof
Residential Roofing

When Is the Best Time to Replace a Roof?

If every day was sunny, mild, and a pleasant 75 degrees, there'd be little reason to wonder about the best time to replace a roof. Of course, not everyone lives in areas with ideal weather conditions, as climates vary greatly across the country.So if a client ever asks, "When is the best time to replace a roof?" your answer will likely vary based on where they live and what each season is like. However, you can share some general pointers in response. Here's what to consider for each season to help answer the question, "when is the best time to replace a roof?"SpringSpringtime is traditionally recognized as the kickoff of roofing season, as outside temperatures begin to warm and activity increases. Thanks to melting ice and snow, it's also the time of year that homeowners may want to have their roofs checked out for damage.While spring offers outdoor temperatures that are more friendly for workers, the season also typically comes with an increased chance of severe thunderstorms (and potentially tornados, depending on the region). Spring is usually a good time to schedule a roof replacement if you just monitor the weather forecast for major events to help reduce the chance of delays.SummerWith spring showers in the rearview, most areas of the country see longer stretches of nice weather during summertime, which lends itself well to working outside. Accordingly, summer tends to be the most ideal time for installing a new roof.But with potentially hot days, when is the best time to replace a roof in the summer? Workers will need to start as early in the day as possible because temperatures are usually cooler in the morning. Depending on the forecast temperatures, the job may need to be spread over a few days, so most of the work can be done in the morning hours before it gets too hot. It's also wise to remind customers that workers will need to have breaks in the shade and access to water to stay hydrated.FallThe autumn months can be an equally good time for a roof replacement as summer, as the hot and hazy days have passed, and severe weather isn't as common. The only exception to this is if you're working in an area prone to hurricanes. Hurricane season runs through the end of November and can cause project delays.In addition to the favorable weather, fall is a popular season for roof replacement because many property owners want to fortify their homes and buildings with a new roof before the winter months.WinterIn some areas of the country, it may be possible to continue roofing installations year-round, including during the winter. In southern regions, for example, roofing replacements can often be completed in the winter, as there's less chance of inclement weather. Temperatures may drop, but not as drastically as in areas that see ice and snow more regularly. Of course, it's still important to reference the relevant local forecast when scheduling upcoming work.Sustained stretches of very cold weather does not constitute suitable weather for the installation of asphalt shingles. All self-sealing shingles must be exposed to warm, sunny conditions for several days before they completely seal. Before sealing occurs, shingles are vulnerable to blow-offs and wind damage. Shingles installed in fall or winter may not seal until the following spring. Shingles that are not exposed to direct sunlight, adequate surface temperatures, or that are not fastened or installed properly may never seal. Failures to seal, blow-offs, and wind damage under these circumstances result from the nature of self-sealing shingles, and are not covered under most manufacturer's warranties. Be sure to follow the manufacturer's instructions for proper installation. While most provide guidance about cold weather installations, it will ultimately be up to you to exercise discretion about when to move forward with an installation vs. postponing the work until more favorable weather conditions are present.Other Factors That May Affect Project TimingWhile weather is likely the leading factor that can disrupt scheduled roofing work, if you want to best answer your client's question of "when is the best time to replace a roof?" you'll need to take other factors into account when setting timeline expectations for property owners. One such consideration is the lead time needed for materials. If your customer chooses an uncommon color or a specialty product, it may take longer for materials to arrive.Another factor to weigh is your own backlog. If your production calendar is booked weeks out, clearly communicate the timing to your customers with the knowledge that weather events could impact the schedule. Regularly communicating with customers and setting accurate expectations are key to a positive experience.Looking to learn more roofing best practices and further expand your knowledge base? Check out GAF's CARE Contractor Training Center to help build your skill set and receive valuable training.

By Authors Karen L Edwards

February 12, 2024

Roofer working on a roof
Residential Roofing

Securing a Roofer Salary for a Competitive and Worthwhile Career

The roofing industry can provide a reliable and rewarding living with potential for growth. As the industry faces an unprecedented labor shortage, pay rates are increasing, and the industry has expanded offerings for training and certification programs to elevate roofing practices across the board.How Much Do Roofers Make?A roofer salary will vary based on a number of factors, including whether the work is residential or commercial. Residential roofing is more straightforward and can usually be completed in a short time.Commercial roofing, on the other hand, may require more specialized training. The jobs are also much larger—sometimes lasting weeks or months, depending on the size and complexity of the roof.The US Bureau of Labor Statistics reports that in the top five states with the highest employment level in roofers, the average annual salary ranges from $42,000 to $63,000. Depending on where in the country you work as a roofer, the annual salary can be as high as $87,000 per year. In 2022, the median roofer salary was reported to be $51,910 annually or $24.96 per hour.What Makes Roofing a Rewarding Career?The roofing industry can deliver a rewarding career with plenty of opportunities for advancement. Being able to work outside every day with amazing views from the rooftop inspires many craftsmen to consider a career in roofing. Often, workers start as an installer and then advance their way up to roles with more responsibility such as project manager, superintendent, estimator, or sales. Some even go on to start their own roofing companies.Working in the roofing industry is typically stable. According to the US Census Bureau, there were roughly 144 million homes across the country as of July 2022. Every one of those homes has a roof that will need to be replaced at some point. On the commercial side, the Commercial Buildings Energy Consumption Survey estimated in their most recent report from 2018 that there are 5.9 million commercial buildings in the US. These commercial buildings will require regular maintenance, repairs, and eventually a new or restored roofing system.What's Elevating the Modern Roofing Industry?Working in roofing was not always seen as a professional, reputable line of work, but organizations like the National Roofing Contractors Association have worked hard to elevate the reputation of the industry. They have established the Training for Roof Application Careers (TRAC) program to provide training for commercial and residential roofing installation as well as prepare workers to become successful foremen and managers.In addition to the TRAC training program, the NRCA has started a ProCertification® program that allows experienced roofing installers to demonstrate their knowledge and skills and become certified in the installation of specific roofing systems.How Can You Get into Roofing?If you think that a career in the roofing industry might be a good fit for you, there are plenty of opportunities. In the past, many installers could only learn on the job. Today manufacturers, including GAF, offer programs that prepare workers to enter the industry.The GAF Roofing Academy is held in locations across the country and offers one- or two-week hands-on training programs that arm you with the skills you need to start your career in the roofing industry. Learn about the experience from recent graduates, and explore upcoming courses in your area.

By Authors Karen L Edwards

January 12, 2024