Helmet cam video from a house fire
Ladder 51 was first in truck to a single family dwelling with a well involved attic fire. First engine stretched a line to the inside, and Ladder 51 went to the roof to cut. Based on 360, it was known that bulk of fire was in Bravo Charlie corner. There was a cross wind coming from the bravo side. Knowing this allowed the crew to perform down cuts into the wind, to ensure visibility was maintained while finishing remainder of down cuts.
This video also shows the importance of understanding what our ultimate goal of ventilation is, and that is the manipulation of pressure. Of course the secondary benefit is smoke removal. After the initial hole is cut, a lot of smoke comes out, but if you look to adjacent areas around the ridge vents, you still see a healthy about of smoke and pressure pushing out. This is an indicator that our hole is not big enough to allow an adequate amount of pressure out. So we simply enlarge the hole by extending the down cuts another 3-4 feet. You can see the difference in the smoke in the adjacent areas once the hole is enlarged.
Considerations for Safe, Effective & Coordinated Vertical Ventilation
How Roof Materials Affect Ventilation Ops
Roof Ventilation: The Cut is the Easy Part
The Why & When of Ventilation
Working on Peaked Roofs