Vertical, horizontal and positive pressure ventilation

A fan at the entry window pushes air toward the fire and the victim, which is the opposite of what this search needs.

Sounding the floor with a tool confirms it will hold before the firefighter commits weight through the window.

Waiting for a roof crew delays a time-critical rescue that does not depend on vertical ventilation.

Breaking the facepiece seal at a smoke-filled window exposes the airway; hearing is no reason to go off air.

From deep in the room the pattern hits the walls around the window and draws little smoke through the opening.

A stream aimed in from outside pushes smoke and heat back into the room instead of drawing them out.

With the tip at the frame, the pattern cannot fill the opening and pulls little smoke along with it.

A short distance inside the window lets the fog pattern fill most of the opening and carry smoke out with it.

Where the fan stands is a setup detail, not the precondition; without a planned exhaust no fan position makes PPV safe.

Many openings bleed off the pressure and send air and fire in unplanned directions.

Pressurized air needs a planned exit; an exhaust near the fire sets the path from the entry, past the fire, to the outside.

With no outlet at the fire, pressurized air pushes heat and fire into other parts of the building.

Smoke-stained windows and smoke puffing at gaps signal a hot, oxygen-starved space; an opening high up lets the fuel-rich gases escape before air comes in low.

Windows at fire level also admit air at the level of the fire, the same hazard as opening a door.

Forcing air into a space with backdraft signs supplies exactly the oxygen it lacks.

Opening a door low on a backdraft-prone space lets air rush in and can trigger ignition of the gases.

Aiming at the wall wastes the airflow instead of driving it through the entry.

Set back from the entry, the fan's cone of air covers the whole opening and seals it, so the building is pressurized.

A fan inside the doorway lets air leak around it and puts the fan in the hazard area.

Tight against the frame and tilted up, the air cone misses much of the opening and pressure is lost.

The secondary search comes after knockdown; holding the vent for it would delay ventilation far too long.

Utility control is a separate task and does not decide when the roof can be opened.

Releasing the rapid intervention crew removes the safety backup; it is never a condition for opening the roof.

Opening the roof feeds air to a ventilation-limited fire, so water has to be ready to go on the fire when the vent is made.

Downwind, the heat and smoke leaving the hole blow directly over the crew.

The section over the fire is the most likely to fail; the cut is placed there, but the crew stays off it.

With the wind at their backs, the products released from the cut are carried away from the crew.

Away from the ladder, the crew has no quick way off if the fire or the roof changes.

A second ladder or an aerial gives the crew another way down if the first one is cut off.

A fan has nothing to do with whether the roof is safe to work on or whether the crew has a way off.

Water on the roof does not make the structure any stronger and can hide warning signs in the decking.

Opening windows before the roof is ready changes the flow path without coordination.

Collapse zones are set by command around the exterior, not by the member searching a room.

Utility control is a separate assignment and is not part of the window search.

Victims are brought toward the window for removal; moving them away is the opposite of the goal.

Shutting the room's door right after entry cuts the room off from the fire and the flow path the open window created.

The roof opening is the exhaust end of the flow path; a stream into it blocks the outflow and pushes heat and smoke back down inside.

The fire draws air from openings below, so a stream at the roof does not starve it of oxygen.

Water does not enlarge the cut; the opening stays the same size while its exhaust is blocked.

Cooling the deck is not the hazard; the problem is what the stream does to the gases trying to leave.

A coordinated vertical opening draws the hot layer up and out of the building, not down toward the floor.

Letting hot gases out over the fire lifts the hot layer, improves visibility, and lowers the radiant heat that drives flashover.

Opening the roof lets air move through the building; it does not starve the space of oxygen.

A roof opening over the fire forms a vertical exhaust; horizontal flow comes from wall openings.

Opening a vent removes heat and smoke but cools nothing by itself, and new air can make the attic fire grow.

Gable vents are in the end walls, so the flow through them is horizontal across the attic.

Venting through an existing gable opening means no one has to climb onto and cut the roof over an attic fire.

A roof opening over the fire releases heat faster than a gable vent; gable venting trades some efficiency for safety.

Spongy decking and fire showing through the roof mean the roof is failing; the crew withdraws at once and reports so command can change the ventilation plan.

Soft spots mark only where failure is visible; the structure around them may already be weakened too.

A smaller hole still keeps the crew on a failing roof; the size of the cut does not change the collapse risk.

A new crew faces the same failing roof; changing people does not change the collapse risk.

An opening far from the fire pulls heat and fire toward it, spreading fire under the roof.

Cutting next to an opening that is already in the right place adds time and weakens the roof for no gain.

Breaking windows is horizontal ventilation and adds air low without giving the vertical exit that was ordered.

An existing opening over the fire is the fastest vertical vent and needs no cutting of the roof.

Decking is checked by sounding and size-up, not by cutting a long strip across the roof.

A trench (strip) cut across the roof ahead of the fire is a defensive cut that stops spread through the attic or cockloft.

Venting the area over the fire is the job of an offensive opening, not of a long cut placed well ahead of the fire.

A cut is never a way off the roof; crews rely on ladders or aerials for that.

Where smoke drifts outside is not the reason for placing the opening; releasing heat from the fire area is.

The area over the fire is the most likely to be weakened, which is why crews work off it while cutting.

Hot gases rise, so an opening right over the seat of the fire lets them out with the least travel through the building.

The opening is there to release heat and smoke; it is not a port for directing water at the fire.

With the hands above the strike, broken glass falls away and cannot slide down the tool onto the firefighter's hands.

Hands below the strike are in the path of glass that slides down the pole when the pane breaks.

At the same height as the strike, the hands are still in range of shards breaking out of the frame.

Getting close to the pane trades reach for exposure to falling glass; the length of the tool is there to keep distance.

A hoseline is needed for hydraulic ventilation, not for letting air move through existing openings on its own.

Natural ventilation relies on convection and wind, so it can be slow or reverse direction when the wind shifts.

Natural ventilation uses no powered equipment; generators belong to fans and ejectors.

Opening doors and windows is routine in houses; the limit is control of the airflow, not the occupancy type.