Short answer: Every metal building has a wind speed rating (in mph) and a snow load rating (in pounds per square foot, or psf). Your county sets the minimums based on local weather history, and your building has to meet or exceed them. Wind ratings commonly run from about 105 to 180 mph, and ground snow loads can reach 30 to 60 psf or more in northern and mountain areas.
Getting this right protects your investment, keeps your permit on track, and is the difference between a building that lasts decades and one that fails in the first big storm.
What is a wind load rating?
A wind load rating is the maximum wind speed a building is engineered to withstand. It is expressed in miles per hour and is based on a design wind speed for your location. Coastal counties, open prairie and hurricane zones require higher ratings because gusts there are stronger and more frequent.
Higher ratings generally mean heavier framing, tighter spacing, extra bracing and stronger anchoring. That is why the same 24x30 garage can be priced differently in two states.
What is a ground snow load rating?
Ground snow load is the weight of snow your roof must be able to carry, measured in pounds per square foot. It is set by local climate data. A roof in a warm southern county may need only a small load, while a roof in the northern plains or mountains may need 30 to 60 psf or more.
Roof style matters too. Vertical-roof and A-frame buildings shed snow better than regular rounded roofs, which is why they are commonly recommended in snowy regions.
How do you find the wind and snow load for your address?
- Ask your building department. They will give you the exact design values they require. This is the most reliable source.
- Ask your building specialist. At Omega, your ZIP code is part of every quote so we can spec the building to your site.
- Check the stamped drawings. The engineer's drawings list the wind speed, snow load and building code edition used.
Avoid guessing from a map or from what a neighbor built. Local requirements can change from one county to the next.
What is the difference between certified and non-certified metal buildings?
| Topic | Certified | Non-certified |
|---|---|---|
| Engineering | Designed and stamped for a stated wind and snow load | Standard design, no stamp |
| Permit acceptance | Accepted by most permit offices | May be rejected in many areas |
| Insurance | Often preferred or required | May limit coverage |
| Typical use | Garages, barns, workshops, commercial | Low-risk areas where no engineering is required |
| Cost | Higher | Lower |
If your county requires engineering, a non-certified building is not a savings. It is a building you may not be allowed to put up.
How do 12-gauge and 14-gauge framing affect the rating?
Gauge describes steel thickness, and a lower number means thicker steel. 12-gauge framing is roughly 25% stronger than 14-gauge, which makes it the better choice for wide spans, tall walls, heavy snow and high winds. For a small carport in a mild area, 14-gauge may be enough. Your specialist should recommend a gauge based on your loads, not just on price.
What else affects how a metal building handles storms?
- Anchoring. The right anchors for your ground type (concrete, asphalt, soil) keep the building attached when wind tries to lift it.
- Roof style. Vertical roofs shed rain and snow more effectively.
- Leg height and span. Taller and wider buildings see higher loads.
- Enclosure. Fully enclosed buildings and open carports react to wind differently, so the engineering must match the final design.
- Site conditions. Hills, open fields and exposure to wind can raise the design requirements.
Common mistakes to avoid
- Ordering a standard building and learning at permit time that you needed a certified one.
- Assuming a rating from a neighbor's building applies to your lot.
- Choosing the cheapest option and skipping the engineering the county requires.
- Adding walls or doors later without checking whether the engineering still applies.
How Omega Metal Buildings handles loads
Every Omega quote is priced for your address and local wind and snow requirements, and your specialist provides stamped drawings when needed. Read more on our permits and engineering page, or start a quote with your ZIP. If permits are your next question, see our guide on whether you need a permit for a metal building.
FAQ
What wind rating do I need for a metal carport?
It depends on your county. Ratings commonly range from about 105 to 180 mph. Your building department can tell you the required design wind speed for your address.
How much snow can a metal building hold?
That depends on the snow load rating it was engineered for. Many northern areas require 30 to 60 psf or more. A building certified for your area is designed to carry the local load.
Is a certified metal building worth it?
If your county requires engineering, yes. Certified buildings are accepted by most permit offices and insurers, while non-certified buildings may be rejected.
Is 12-gauge steel better than 14-gauge?
12-gauge steel is thicker and about 25% stronger, so it is better for wide spans, heavy snow and high winds. For small buildings in mild climates, 14-gauge can be adequate.
Can I upgrade the wind or snow rating later?
Usually not. Ratings are built into the engineering, framing and anchoring, so it is best to choose the correct rating before the building is made.
Last updated November 2026. Design values vary by location and building code edition; confirm requirements with your local building department.