SLOPE TOP v Underground

Garage underground

SLOPE TOP                                    UNDERGROUND

Features Slope Top Vortex Vault Underground
EF 5 Rated Tornado Safety YES YES
Alternate Function YES - BED NO
Climate Controlled YES - INSIDE HOME NO
Handicap accessible NO NO
Electric Power Supply YES NO
Battery Powered USB YES NO
Locked Storage YES - optional YES


It's difficult to compare the two shelter styles, considering the numerous advantages presented with the Slope Top. While some people may still be under the impression that underground shelters are a safer option (see our website page regarding safety), the reality is that above ground shelters have delivered better results in both experimental settings, and actual severe weather events.  Above ground shelters reduce the potential for drownings with shelters flooding, a factor that excludes many homeowners from qualifying for rebates on underground shelters. Additionally, more injuries occur from individuals falling down the steep stairs, than occur from storm related injuries inside an EF 5 rated shelter. As a matter of fact, not a single person has died in an above ground shelter that was tested to meet FEMA standards.

As for comfort, the Slope Top is clear winner for convenience. Being inside the home, means the shelter stays the ambient temperature of the home.  Underground shelters tend to be comfortable and cool, but they can become stuffy if air is not circulated, and usually have a dampness, and musty odor.  Electricity, battery back up system, lighting, and fans can be installed in underground shelters, but are not standard, and tend to increase the price substantially.  On the other hand, all of these features (except for the fan) are included with all Vortex Vaults shelters.

The Slope Top shelters are available in Full, Queen, or King bed sizes.  This limits occupancy to 3 persons, or 4 with a King size bed.  This advantage shifts to underground shelters for larger families.  However, as the size increases so does the price.  Speaking of, the price between a Slope Top, and underground shelter are comprable, with the underground shelters starting a few hundred dollars less in some cases, but more expensive in certain regions of the US. A better comparison for larger size shelters is between the Vortex Vault 3 Tier Model, or Project Station.  Check the other blog posts for those comparisons.