Practical Planning Guide
Planning Your Shelter
How occupancy and duration translate into area, systems, habitability, cost and programme time — before a footprint is drawn.
Start with duration
Duration is the first consequential number. It drives stored water and food, waste handling, power capacity, sleeping strategy, mechanical redundancy and the amount of space people can realistically tolerate.
Count occupancy honestly
Include family, extended family, likely future spouses and grandchildren, trusted associates, caretakers and pets. Designing around the people who happen to be in the room today produces a shelter that is undersized before it is finished.
Area planning
FEMA guidance is roughly 60–66 square feet per person for stays beyond 24 hours. For longer occupancy, approximately 100 square feet per person is a more realistic planning figure. An airlock adds roughly 27 square feet and a decontamination room roughly 38.
What has to fit
Area is not only beds. The footprint must hold sanitation, food and water, mechanical and electrical plant, generation, communications, food preparation, personal storage and a place to sit, work and recover.
Habitability over weeks
Long stays require separated sanitation, sleep rotation, exercise, continuous lighting and reliable communications. Underground temperatures commonly remain around 45–65°F; that stability is useful, but insulation, dew-point control and dehumidification still determine whether the interior remains healthy.
Site and ground conditions
Topography, equipment access, soil, rock depth, groundwater, frost, and seismic conditions affect the excavation, concrete structure, drainage, schedule, and budget. Important projects should use appropriate geotechnical investigation rather than visual assumptions alone.
Water management
A waterproof coating is not a drainage strategy. Grading, perimeter drains, free-draining aggregate, continuous membranes, waterstops, sealed penetrations, accessible sumps, alarms, and backup power must be coordinated for the actual site before the structure is buried.
Permitting and privacy
Structural, electrical, plumbing, mechanical, septic, and well work may involve different authorities. Privacy comes from disciplined information control, limited plan distribution, project-specific NDAs, and careful scheduling — not from inaccurate permit documents.
Threat-informed review
Where appropriate, Hardened Structures can coordinate a confidential red-team review of a proposed site or existing building with vetted former special-operations security professionals. The assessment examines realistic vulnerabilities and informs site planning, access, hardening, and response priorities without publishing tactical details.
Cost ranges
Custom underground concrete shelter projects usually exceed $750 per square foot. Difficult access, rock, groundwater, protection level, independent systems, and residential finishes can move the result substantially higher. These are planning figures, not quotations; a credible range follows site and programme review.
Timeline
Serious shelter programmes spend several months in programming, investigation, engineering, and permitting before construction begins. That work resolves expensive questions on paper, while changes are still comparatively inexpensive.