The engineering, and its limits
What a Qilyx shelter withstands, how it keeps people alive while sealed, and what no private shelter can survive.
Every component, standard and lead timeIf a missile is aimed at a shelter, the shelter will not survive.
We say this first because it matters most.
In June 2025, specialised bunker-busting bombs were used against Iran's Fordow enrichment site, built under tens of metres of rock. No private shelter is built that deep. A precision strike aimed at a shelter will destroy it.
But direct hits are not how most people are harmed in a war or a nuclear event. Most harm comes from fallout drifting downwind, blast and debris at a distance, fires, toxic air, and weeks without water, power, medicine or food. That is what Qilyx shelters are built to survive. Not being known is the best defence against being targeted, which is why discretion is part of the engineering.
1. Fireball and crater
Not survivable by any shelter.
2. Severe blast
Most buildings destroyed. Citadel and Estate shelters, rated 2 bar and above, may survive, without guarantee.
3. Moderate blast and fire
Buildings collapse and fires spread. Every class is designed to survive this.
4. Fallout
Can stretch tens to hundreds of kilometres downwind. Where shelters save the most lives.
Distances depend on weapon size, burst height and weather, so we do not quote fixed radii.
Radiation: how thick is thick enough?
Mass stops radiation. Each material has a halving thickness that cuts fallout radiation in half. Ten halvings cut it about a thousandfold.
| Material | Halves it | 1,000× less |
|---|---|---|
| Steel | 1.8 cm | 18 cm |
| Concrete | 5.6 cm | 56 cm |
| Packed earth | 8.4 cm | 84 cm |
| Water | 12 cm | 1.2 m |
A Keep shelter has a 500 mm concrete roof under at least 1.2 m of earth: on paper, more than 20 halvings.
In practice the entrances, air shafts and hatches are the weak points, because radiation scatters around corners. Entries turn at right angles and shafts are baffled. Our protection factors of 1,000 to 10,000 already account for the openings.
A protection factor of 1,000 means people inside receive one thousandth of the dose outside.
Shielding calculator
Starts at an ordinary 150 mm concrete roof with no earth. Move the sliders to see the effect of a shelter roof and earth cover.
Theoretical straight-through shielding. Real shelters are limited by their openings. Read the full guide: how thick should bunker walls be?
Walls, roof and blast
Ordinary houses are badly damaged at about 0.35 bar of blast overpressure. Reinforced concrete buildings fail at roughly 1 to 1.5 bar.
1 bar
The Swiss civil protection baseline, used for Haven and Keep. Survives where most buildings above are destroyed, outside the fireball and crater.
2 bar
Citadel. Thicker structure, deeper earth cover, stronger doors and valves.
3 bar and above
Estate, designed case by case with depth and heavy structure.
Blast doors and valves
Gas-tight steel doors. Valves on every air opening close in milliseconds when a pressure wave arrives.
Debris loads
Roof slabs carry the weight of collapsed structures above plus earth. Escape hatches sit outside any collapse zone.
Earthquakes
Designed to IS 1893 for your seismic zone and IS 4991 for blast. Fittings are shock-mounted.
Clean air, three levels
Every system keeps the shelter at positive pressure, so filtered air leaks out and outside air never leaks in. All include a hand-crank backup.
| Feature | Essential | Advanced | Elite |
|---|---|---|---|
| Standard on | Haven | Keep, Citadel | Estate |
| Particle filter | HEPA H13 | HEPA H14 | HEPA H14, twin |
| Gas filter | Activated carbon NBC | Military-grade CBRN | Twin CBRN, auto changeover |
| Recirculation mode | No | Yes, CO₂ scrubbing | Extended, oxygen reserve |
| Monitoring | CO₂, CO | + O₂, humidity, radiation | + chemical detection, remote alerts |
| Cooling | Inverter unit | Unit + standby | Redundant plant |
Why recirculation
When fires burn outside, even filtered air carries smoke and carbon monoxide. Recirculation closes the intake and scrubs the air already inside.
Why cooling matters
The ground stays near the local average temperature, often 24 to 28°C, but each person gives off about 100 watts. Without cooling, a full shelter overheats in hours.
No flames inside
Cooking is electric. Generators sit in vented enclosures with exhaust far from the intake. Carbon monoxide alarms are standard.
Water, power and sanitation
Stored water
At least 4 litres per person per day for drinking and cooking, plus reserve, in food-grade tanks rotated by our team.
Purification
RO and UV, plus gravity filters that need no power. Estate shelters can draw from a protected borewell.
Power
Lithium iron phosphate batteries, concealed solar and generators with stabilised fuel.
Load priorities
When power runs low, comfort loads go first and air goes last. Air never stops.
Sanitation
Chemical or flushing toilets with sealed holding tanks. Backflow valves keep the sewer line closed.
Communications
Shielded radios for official broadcasts and licensed two-way radio. Satellite only where Indian law permits.
Food, planned with you
About 2,200 kcal per adult per day, adjusted for children, elders and medical needs, with a 10% buffer. Each diet has its own store and utensils.
| Diet | What we stock |
|---|---|
| Vegetarian | Ready dal, rajma, chole, khichdi, poha and sabzi; nitrogen-packed rice and atta; ghee, milk powder, dry fruits, jaggery |
| Non-vegetarian | Ready chicken curry, keema, biryani, egg powder, canned fish, stored separately |
| Jain | No onion, garlic or root vegetables. Jain-certified meals in a sealed, separate store |
| Vegan and satvik | Plant proteins, dals, plant milk powder; simple satvik staples |
| Halal | Halal-certified meat and meals |
| Medical | Diabetic, gluten-free, soft diets, infant formula and allergy-safe stores |
We replace stock before it expires, and plan for fasts such as Navratri, Ramadan and Paryushan.
Standards we design to
- IS 456: reinforced concrete
- IS 1893: earthquake-resistant design
- IS 4991: blast-resistant design
- National Building Code of India 2016
- Swiss Federal Office for Civil Protection shelter guidelines, as a performance benchmark
- NDMA guidelines on nuclear and radiological emergencies
How these compare with Swiss, Finnish, US and Israeli practice: what the world follows.
Designing for Indian conditions is covered in depth in our guide to heat, monsoon and earthquakes.
Every design is checked and signed by a qualified structural engineer. Figures on this site are design targets, not guarantees. Ratings for your shelter are written into your contract.
Ask us the hard questions.
We would rather lose a project than oversell protection.