Review of Ventilation Principles & Practices

This in-depth, monthly MFRI firefighter drill helps readers understand the principles of ventilation, including the various types and tools needed.

Session Reference: 1

Topic: Review of Ventilation Principles & Practices

Time Required: 3 hours

Materials: Chalkboard


   • IFSTA Essentials of Firefighting, 3rd Edition



Student Performance Objective (SPO):

The student will demonstrate a basic understanding of the principles of ventilation, the safety precautions to be taken when ventilating a structure and how to use the various types of ventilation through class discussion and participation.


   • Review of ventilation principles

   • Safety precautions during ventilation

   • Review of the various types of ventilation

Session 1 Review of Ventilation Principles & Practices

SPO 1-1 The student will demonstrate a basic understanding of the principles of ventilation, the safety precautions to be taken when ventilating a structure, and how to utilize the various types of ventilation.

EO 1-1-1 Demonstrate an understanding of the principles of ventilation and how it effects fire suppression operations.

EO 1-1-2 Demonstrate an understanding of the precautions to be taken during ventilation operations as they relate to firefighter safety.

EO 1-1-3 Demonstrate an understanding of how to utilize horizontal, vertical, trench, hydraulic and mechanical ventilation.


I. Principles of Ventilation (1-1)

A. Ventilation ---- the planned and systematic removal of heat, smoke and toxic gases from an area and the replacement of these products with cooler fresh air.

B. Effects of proper ventilation

  1. Better visibility

  2. Reduced temperature levels

  3. Reduced possibility of backdraft or flashover

  4. Easier to locate seat of fire or victim

  5. Reduced smoke damage to property

C. Advantages of ventilation toward fire suppression operations

  1. Assists with rescue of victims

  2. Increases fire attack

  3. Reduces possibility of backdraft/flashover

  4. Aids in property conservation


II. Safety Precautions (1-2)

A. When ventilating a structure, firefighters should wear full protective equipment and SCBA.

B. Always vent at the highest point if possible.

C. Have hoselines in place and ready to make your attack.

D. Always work with the wind at your back or side when cutting vent holes or venting windows

E. Never place a hoseline or elevated fire stream into a ventilation opening.

F. Check the stability of the roof before starting ventilation operations.

G. Restrict number of personnel working on roof to minimum to accomplish task.

H. Always work from a roof ladder when cutting hole on a pitched roof.

I. Watch out for overhead power lines.

J. Have a secondary escape route from roof.

K. Check power tools on the ground to make sure they will start before taking to the roof

L. Be careful not to cut main structural supports

M. Watch out for signs of unsafe roof conditions.

N. Maintain communications capability with ventilation crew.

O. Remove crew from roof after ventilation hole is completed.


III. Types of Ventilation (1-3)

A. Horizontal Ventilation

  1. Use of doors and windows to ventilate across the floor of a building

  2. Open leeward side windows first, at top

  3. Open windward side windows next, at bottom

  4. Keep ventilation openings clear from all obstructions

B. Vertical Ventilation

  1. Opening made above the fire to relieve heat and gases due to mushrooming

  2. Ventilation opening should be made directly over fire and at the highest point

  3. Utilize any natural openings already there such skylights, scuttle holes, exhaust fans, etc.

  4. Ventilation openings should be large enough (minimum of 4' x 4')

  5. Openings cut on pitched roofs should be on leeward side and as high as possible.

  6. Make sure opening is clear from any material or obstruction.

C. Trench Ventilation

  1. Used in buildings with large attic areas to stop horizontal spread of fire.

  2. Four foot wide opening cut in roof from outside wall to outside wall.

  3. Opening must be far enough away from fire to allow it to be completed before fire gets there.

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