Above-ground vs underground storm shelters: the St. Louis answer

Last updated: October 10, 2026

For most St. Louis homes without a basement, an above-ground steel safe room is the better choice. Both types can be built and tested to the same FEMA P-361 and ICC 500 criteria for a 250 mph design tornado, so the difference isn't the protection on paper — it's water and access. Slow-draining soils are common, large parts of the region sit in river floodplains, and an above-ground room opens at floor level for anyone who can't manage steps. Underground still works on high, well-drained sites, and an in-ground garage unit is a reasonable middle option where the ground stays dry.

The comparison

Why water decides it here

Soil. Where soils drain slowly, an excavation fills with water in wet weather, and a shelter set in it sits against saturated backfill. Good drainage design helps; it can't change the soil. The site check tells you which kind of ground you have.

Floodplains. The Missouri and Mississippi river bottoms, the Meramec and River des Peres valleys, and the American Bottom on the Illinois side — protected by a 74-mile levee system that was certified to 100-year protection in 2018, with all systems accredited by 2022 — are places to stay above ground. FEMA's grant guidance says safe rooms generally shouldn't be sited in special flood hazard areas, and a residential tornado safe room's floor should be at least a foot above the base flood elevation.

Storm rain. Tornadoes here often come with heavy rain. Garages take on driveway runoff; yard shelters sit where surface water collects.

Why access matters as much

The best shelter is the one everyone actually gets into in time. Above-ground rooms open at floor level, inside the house or attached garage. In-ground garage units need someone to move the car and everyone to climb down. Yard shelters need everyone to go outside, at night, in rain and wind, then down.

For a household with an older parent, a wheelchair user, or small children asleep upstairs, that difference outweighs everything else. Our capacity and access guide has a one-minute test you can run tonight.

The garage-slab exception

If you have a slab-on-grade home and a garage that stays dry, an in-ground garage unit gets you below ground without going outside and without giving up floor space. It's a good fit for many newer St. Charles County homes — provided the site check for water passes. If it doesn't, the same garage takes an above-ground unit. See installing in an existing garage slab.

When underground is the right call

• High, sloped, well-drained rural lots, typical of parts of Franklin, Lincoln and Warren counties.
• A manufactured home on a large lot without a suitable slab for an above-ground unit.
• An owner who values a hidden shelter and accepts the access trade-off.

Franklin and Jefferson counties each have about 9% of their housing in mobile homes (Census, 2020–2024), which is where a shelter outside the house makes the most sense. See mobile home tornado safety.

What about basements?

If you have a basement, the question is different: you already have a below-ground space. A safe room in the basement adds tested protection to a space that's already out of the wind. See basement vs safe room.

Decision guide

1. Basement? Start with a basement safe room — unless it floods or someone can't manage the stairs.
2. No basement, someone with mobility needs? Above-ground.
3. No basement, in or near a floodplain? Above-ground, above flood elevation.
4. No basement, dry garage, everyone can manage steps? In-ground garage or above-ground — your preference.
5. Rural, high and dry, no suitable slab? Underground can work.

Our shelter planner walks through the same questions.

Related guides

• Flood risk and shelter location
• Storm shelter cost in St. Louis
• The complete St. Louis storm shelter guide

Frequently asked questions

Which is safer, above ground or underground? Units tested to the same criteria are designed for the same tornado. Around St. Louis, above ground avoids the water and access problems that underground brings.

Will an above-ground shelter blow away? Not if it's anchored to a slab that meets the manufacturer's specification. The anchorage is part of what's tested.

Can an underground shelter flood? Yes, if the site is wet or in a floodplain. That's why the site check matters.

Is a storm cellar the same thing? An old cellar is a below-ground room, but older cellars weren't built to today's criteria.

Get a quote

Not sure which fits your home? Our installation crew will check the site and recommend one — including telling you when a yard unit does fit. See underground storm shelters, or get a quote.