Should I lock or brace my garage door before a tornado in Colorado?

The garage door is the largest opening in most homes and the part most likely to fail first in a tornado. Standard residential doors are not built to resist tornado-level wind pressure, and locking them with a throw-bolt can actually make the damage worse. This page covers what to do and what not to do in the minutes before a tornado warning on the Colorado Front Range.

Why locking a standard door before a tornado can backfire

A throw-bolt lock (the sliding bar lock on the inside of the door) holds the door against the floor. In a tornado, the wind pressure acts against the full surface of the door, not just the bottom. When a locked door cannot flex or release at the bottom, the middle sections buckle first. The result is more damage to the door and more risk that the door frame tears away from the garage opening, which allows air pressure to enter the structure rapidly.

DASMA TDS-192 specifically addresses securing doors during high-wind events and cautions against using standard locks as the primary protection. The reasoning is structural: a locked, unbraced residential door does not become a wind-rated door. It becomes a fixed panel that fails in a different and often more destructive way.

The opener emergency cord (red handle hanging from the trolley rail) is a related concern. If you pull the emergency cord and disconnect the door from the opener before a storm, the door can travel up and down freely on its own. An unlocked, disconnected door can blow open in wind even before the worst of the storm arrives. Leave the opener connected unless there is a power issue that forces you to disconnect it.

What you should do in the minutes before a tornado warning

When a tornado warning is issued for your area, the safest immediate steps are:

1. Leave the garage door in the closed position. Do not open it for any reason during the warning period.
2. Keep the opener connected to power and the door trolley. This holds the door in place using the opener's mechanical connection to the rail.
3. If your opener has a vacation lock or similar security mode, activate it. This prevents the door from being opened remotely but keeps the opener mechanically attached.
4. Move away from the garage interior and go to an interior room on the lowest floor, away from windows.

Do not attempt to manually brace a standard door with boards, jacks, or improvised materials during an active tornado warning. The time required is not available, and bracing that is not engineered for the door can create new failure points.

Pre-season bracing kits: what they can and cannot do

Steel C-channel vertical braces exist as aftermarket products that bolt to the sections of a garage door. These braces add rigidity to each door section and reduce the risk of the door bowing inward under pressure. DASMA TDS-191 covers tornado wind mitigation options including bracing systems.

However, bracing kits have important limits:

• They must be installed before the storm, ideally at the start of the severe weather season (May in Colorado). Installation during a warning is not feasible.
• Bracing improves section rigidity but does not upgrade the track, hinges, or mounting hardware. In a true tornado, the track and anchor bolts must hold the full wind load, and standard residential hardware is not rated for tornado conditions.
• Bracing kits are not approved as a substitute for a wind-rated door in jurisdictions that require wind load compliance for new or replacement doors.
• The effectiveness of any brace depends on the door design. Some door section profiles are not compatible with aftermarket bracing.

If you want a bracing kit, purchase and install it before tornado season. Your door installer can tell you whether your specific door is compatible with available brace systems.

Colorado tornado risk by county and month

Colorado is not in the core of Tornado Alley, but the Front Range east of Denver has documented tornado activity. The Colorado Climate Center records tornado touchdowns most frequently in Weld, Morgan, Adams, and Logan counties. The peak season runs from May through August, with June being the highest-risk month. Tornadoes in this region are often brief but can produce winds exceeding 130 mph in the strongest events.

Derecho-level straight-line winds also occur on the Front Range, sometimes reaching 80 to 100 mph along the I-25 corridor and in Larimer and Boulder counties. These wind events produce similar pressure loads on garage doors as weak tornadoes, and the door failure risk is comparable. A door that might survive a 60 mph gust can fail at 90 mph straight-line wind even without a rotating storm.

Colorado county cluster	Tornado frequency (average events per year)	Peak months
Weld, Morgan, Logan	3-5 events	June-July
Adams, Arapahoe	1-2 events	May-July
Larimer, Boulder	Less than 1 (derecho risk higher)	June-August
Denver metro (urban core)	Rare	June-July

The most reliable protection: a wind-rated door

DASMA TDS-191 and TDS-192 both conclude that the best protection is a door designed and rated for elevated wind loads before a storm event. WindCode-rated doors (Clopay's system, W1 through W8) and ASCE 7-based rated doors from other manufacturers include heavier steel, additional horizontal struts across each section, reinforced hinges, and hardware rated for higher loads.

For most Colorado Front Range locations, a standard wind-rated door in the W2 to W3 range (roughly 25 to 35 PSF, equivalent to 100 to 115 mph design wind) provides meaningful protection against the majority of wind events in the region. True tornado-rated doors exist but are more common in Gulf Coast and Florida markets where High-Velocity Hurricane Zone (HVHZ) requirements apply.

If your garage door is more than 15 to 20 years old and in an exposed location, a replacement door with basic wind-load reinforcement is a reasonable investment before the next tornado season.

When shopping for a wind-rated door, look for two things on the product label: the design pressure rating in PSF and the wind speed that rating corresponds to. DASMA TDS-194 explains the relationship between PSF and MPH so you can compare products fairly. A door labeled for 30 PSF withstands approximately 110 mph winds. For most Front Range metro locations, 30 PSF covers the risk profile of typical severe weather events, including the majority of F1 and F2 tornadoes that have touched down in Weld and Adams counties.

Also ask about the mounting hardware. A wind-rated door section on standard residential track and anchor bolts does not deliver its full rated capacity. The track gauge, end bracket thickness, and anchor bolt size all factor into how well the system holds under load. A full wind-load installation uses heavier horizontal and vertical track with additional anchor points into the structural framing of the garage opening, not just the drywall or siding.

One practical step you can take before tornado season: open your garage door manually, look at the horizontal struts running across each section, and count them. A standard 7-foot-tall residential door has one strut on the top section. A wind-reinforced door has struts across every section or at mid-section points on taller door panels. If your door has only a single top strut, its resistance to midspan pressure is limited. This visual check takes less than five minutes and tells you quickly whether your door was built with wind loads in mind.

G Brothers serves the Denver metro and Front Range with same-day service and free estimates on door replacement and wind-load reinforcement options.