Residential Fire Egress & Smoke Tenability Simulator

Smoke and toxic carbon monoxide kill faster than flames. Test how interlinked alarms, nighttime closed internal doors, and prompt awakening dictate your Available Safe Egress Time (ASET) before hallway stairwells turn lethal.

Load Layout Archetype:

Fire & Protection Scenario

Fire Origin & Fuel Type Smoke Alarm Grade Interlinked alarms sound all units the instant any single detector trips. Time of Incident & Occupant State

Critical Door Management Closing doors isolates smoke for 15–20 min

Primary Egress Obstruction Clear

Interactive Floorplan & Smoke Density

Hover or click rooms to inspect temperature & smoke obscuration

T-ELAPSED: 00:00 STANDBY

0s / 360s

Detection Time

Alarm trigger point

Stairwell Untenable

Optical obscuration > 0.15 OD/m

Egress Margin (ASET - RSET)

Safety buffer remaining

Escape Verdict

Ready

3 Occupants tracked

Occupant Escape Status Tracker Standard human toxic threshold: 30-min CO > 1200 ppm

Select parameters or scrub timeline to model smoke progression.

The Physics of Residential Egress

In contemporary homes filled with synthetic furnishings (polyurethane foams, MDF, plastics), a room reaches flashover in under 3 to 4 minutes—compared to 25 minutes 40 years ago.

ASET (Available Safe Egress Time): The interval between fire ignition and when environmental conditions (hot toxic layer descent, carbon monoxide > 1,000 ppm, zero visibility) become lethal along escape corridors.
RSET (Required Safe Egress Time): Total time required to detect the fire + recognize/wake up + decide on an action + physically travel to a safe final exit outside.
Stairwell Chimney Effect: Hot smoke buoyancy creates a thermal siphon, channeling superheated toxic gases up open staircases directly into sleeping quarters within 90 seconds.

Standard UK Fire Service Life-Saving Rules

Why Close Internal Doors at Night?

A standard 35mm solid core or even hollow wooden interior door can hold back smoke, lethal carbon monoxide, and radiant heat for 15 to 20 minutes. It converts an unviable house into isolated survivable compartments, keeping the staircase passable.

Why Interlinked Smoke Alarms (BS 5839-6)?

If a fire ignites in a ground floor kitchen or consumer unit, a standalone alarm on the upstairs landing may not sound until smoke has already flooded the stairs. Interlinked alarms sound immediately in all bedrooms the moment smoke enters the kitchen.

Deadbolts & Window Egress

Never lock key-operated deadbolts without keeping keys permanently by the door. If primary stairs are blocked, second-floor egress windows (minimum 0.33 m² openable area, at least 450mm width/height) provide a secondary escape or rescue point.