Choosing the right wind rating is one of the most important decisions you'll make when buying a metal building. Yet, many buyers aren't immediately aware of how the framing changes between a 145 MPH certified structure and one engineered for 170 MPH winds.
While both are designed to meet strict engineering standards, the framing, bracing, and anchoring systems are built differently to accommodate heavier loads.
This guide explains what actually changes between 145 MPH and 170 MPH certified metal buildings and why those differences matter for long-term storm protection.
Key Highlights
- Wind ratings are engineered according to the ASCE 7 standard used by U.S. building codes.
- A higher wind rating generally requires stronger framing, additional bracing, and upgraded anchoring systems.
- 170 MPH certified buildings often feature tighter truss and leg spacing to better distribute wind loads.
- Wind and snow load certifications are engineered together to match local environmental requirements.
- Required wind ratings vary by county, municipality, and geographic location.
- Higher wind ratings may be required in coastal and high-wind regions.
- Selecting the proper wind rating helps ensure your building complies with local codes while providing reliable long-term performance.
What Does Wind Rating Actually Mean?
A wind rating is the maximum wind speed a structure is engineered to withstand under the requirements of the American Society of Civil Engineers' ASCE 7 standard. Rather than representing a simple "survival speed," the rating is based on detailed engineering calculations that evaluate how wind forces affect the roof, walls, framing, and foundation connections.
Wind certification is typically paired with a specific snow load rating because both factors influence the structural design. An engineer evaluates how wind pressure, uplift, and vertical loads work together before determining the required framing specifications.
Wind requirements are not identical across the country. Building departments adopt local code requirements based on regional weather patterns, so one county may require a different certified wind rating than another located only a short distance away. Coastal communities, hurricane-prone regions, and certain commercial applications often have more demanding structural requirements than inland locations.
Related DMS guide: See how local design loads affect steel buildings in Wind & Snow Resistance.
What Changes in the Framing Between a 145 MPH and a 170 MPH Structure
Although 145 MPH and 170 MPH certified buildings may appear very similar from the outside, several structural components are engineered differently beneath the surface. Higher wind ratings generally require modifications to the spacing, steel members, bracing, and anchoring systems used throughout the building.
These framing differences aren’t universal between providers, but they do give you an idea of what alterations may happen when upgrading from 145-170 MPH wind ratings:
| Factor | 145 MPH Tier | 170 MPH Tier |
|---|---|---|
| Frame / Leg Spacing | Standard engineered on-center spacing | Tighter engineered on-center spacing where required |
| Steel Gauge | Standard engineered framing gauge | Heavier framing members where engineering requires additional strength |
| Anchoring | Standard engineered anchor package | Upgraded engineered anchor package |
| Bracing | Standard engineered bracing | Additional bracing and reinforced connection points |
| Typical Region | Most inland and standard-wind regions | Coastal, high-wind, and hurricane-prone regions |
| Documentation | Engineer-certified | Engineer-certified, often required for coastal or commercial permitting |
Frame Gauge and Steel Thickness
Higher wind-rated buildings frequently incorporate heavier 12-gauge steel framing in critical structural areas as opposed to the traditional 14-gauge steel. Increasing the strength of these members helps the building resist bending, buckling, and deformation when exposed to higher wind pressures.
Compare framing options: Read What Gauge Framing Do I Need for Wind and Snow Zones?
Truss and Leg Spacing
Buildings designed for higher wind ratings commonly use tighter truss and leg spacing. By reducing the distance between structural supports, wind forces are distributed across more connection points instead of concentrating loads in fewer areas.
Anchoring and Foundation Connections
The anchoring system plays a critical role in every certified building. Higher wind ratings typically require upgraded anchors and engineered foundation connections to help resist uplift and lateral movement during strong winds.
See how the roof, uplift, and anchors work together: Read Regular vs A-Frame vs Vertical Roof: Spanning, Drainage & Uplift.
Why the Upgrade Matters
Certification guarantees your building meets local wind and snow requirements and is engineered for the conditions where it’s installed. It can help with:
- Storm Protection
Buildings engineered for higher wind ratings incorporate additional structural reinforcements that help manage increased wind pressure and uplift forces. - Insurance Coverage
Many insurance providers consider whether a structure has been engineered to meet applicable building codes for its location. - Resale Value
An engineer-certified building designed for the appropriate wind zone can be an attractive feature for future buyers.
Which Wind Rating Do You Need?
The correct wind rating depends on several factors, including your county's adopted building code, local wind zone, intended building use, and geographic location. Properties located near the coast or in hurricane-prone regions often require higher certified wind ratings than similar structures farther inland.
Before manufacturing begins, the required wind and snow loads should be verified to guarantee the building is engineered for your installation site.
Explore customizable building options
SKU #DMS27
30x40 Three Car Garage
A side-entry three-car layout on a 12' eave — enough width for three bays and enough height for taller trucks.
Width30'Length40'Eave12'
Specifications as shown Car capacity 3 Garage doors 3 Walk-in doors 1 Windows 2 Entry type Side Roof type Vertical Frame gauge 14 Sheet metal gauge 29 gauge steel
- Delivery & installation included
- Financing and Rent-to-Own available
- Certified options available
SKU #DMS79
36x40x12 Metal Barn
A front-entry barn with lean-to sides — equipment storage down the center, covered work or shelter space along the wings.
Width36'Length40'Eave12'
Specifications as shown Car capacity 4 Doors 4 Lean-to Yes Windows 3 Entry type Front Roof type Vertical Frame gauge 14 Sheet metal gauge 29 gauge steel
- Delivery & installation included
- Financing and Rent-to-Own available
- Certified options available
SKU #DMS33
40x60 Clear Span Garage
2,400 sq ft with no interior columns — the full 40' width stays open for equipment, work bays or commercial use.
Width40'Length60'Eave12'
Specifications as shown Interior Clear span Garage doors 2 Walk-in doors 2 Windows 2 Entry type Front Roof type Vertical Frame gauge 14 Sheet metal gauge 29 gauge steel
- Delivery & installation included
- Financing and Rent-to-Own available
- Certified options available
Why Buy Your Wind-Rated Building from Direct Metal Structures
Direct Metal Structures is a premier choice for certified metal buildings, metal garages, metal barns, and RV covers. Every structure we create is designed to meet the wind and snow load criteria for your region and customized to fit your way of life.
When you work with us, you'll always receive:
- Certified structures engineered for your required wind and snow loads
- Fully customizable building designs tailored to your property
- Professional delivery and installation
- Flexible financing and Rent-to-Own (RTO) options
- Access to our easy-to-use 3D Designer tool for customizing your building before ordering
Whether you're planning a garage, workshop, agricultural building, commercial structure, or equipment shelter, our team is ready to help you select the right certified building for your project. Call Direct Metal Structures today at 888-277-7950 to begin designing your custom metal building.
Ready to plan your purchase? Review Financing Options or Rent-to-Own. You can also call 888-277-7950.
Frequently Asked Questions
1.
What does a wind rating like 145 MPH or 170 MPH actually measure?
Answer: A wind rating identifies the wind speed a building has been engineered to withstand according to ASCE 7 structural standards. It reflects how the framing, bracing, and anchoring systems work together under calculated wind loads.
2.
What is the real difference between a 145 MPH and 170 MPH rated building?
Answer: The primary differences involve structural engineering. A 170 MPH certified building may include tighter framing spacing, additional bracing, upgraded anchoring systems, and heavier framing members where engineering calculations require increased strength.
3.
Do I need a 170 MPH rated building for my area?
Answer: Not necessarily. The required certification depends on your local building code, county requirements, property location, and intended use.
4.
Does a higher wind rating cost more?
Answer: Higher wind-rated buildings generally require additional structural materials and engineering, which can increase the overall investment.
5.
Will DMS provide documentation for permits?
Answer: Yes. Our certified buildings include the engineer-stamped drawings required for permitting.
6.
What roof style is best for a high-wind metal building?
Answer: Vertical roof systems are often recommended for larger buildings and areas that experience heavier wind or precipitation.
Conclusion
While a 145 MPH and a 170 MPH certified metal building may share a similar appearance, the engineering behind each structure is built to different design requirements. Changes in framing, truss spacing, bracing, and anchoring allow higher-rated buildings to handle increased wind loads and meet stricter local code requirements.
The best choice is always one that's engineered for your specific site. Direct Metal Structures can help you determine the wind requirements for a structure in your region.
Get the right wind rating for your site
Call and we will walk through the wind and snow loads your location requires — or use the 3D Designer to customize a building on your own.
Delivery & installation included • Financing and Rent-to-Own available
