When should we vent modern vs older and commercial vs residential construction? Should we do it as soon as we arrive or should we wait until interior crews ask for it? This is a big debate in both my departments. I think that as soon as we have an attack crew ready to enter the building ventilation should take place. We have to be cautious with this though because the attack crew doesn’t need to be held up for ventilation. Also we don't need to have ventilation in place way before the attack crew is at the door ready to make entry. How do we vent, vertical vs. horizontal? Again this is a big debate in both my departments. In this matter I feel the best option is vertical ventilation. I know a lot of people will bring in the factors of manpower, time, and safety. I know and agree with all these factors, but all in all vertical vent is our best option. My reasoning behind this is the safety of the interior crews, first and foremost, and the issue of exposures. It is better to get those super heated gases up and away from all our crews and everyone operating on the fire ground. Then there is the factor of exposures. You are more like to compromise exposures with horizontal vent because the super heated gases are primarily at the same level as your exposure. I think all these factors apply to all types of construction.
I concur with Trevor. Ventilation is an ongoing process. From start to finish venitlation, in some form is occurring. When we perform ventilation, we are trying to control this natural process so we reap the benefits. A factor is to not allow it to work against us. Venting anything takes discipline and must be done with the entire operation in mind.
Vent for life - taking a window to allow the heat and gases to escape so life can be preserved.
Vent for fire - much more coordinated with suppression and vertical is the best method if it is possible.
Vent high, vent for maximum effect but the conditions will warrant the method.
I like Trevor's and Chris's answers and would add that ventilation must be truly understood so that we can predict the likely outcomes of our actions. For many years there was so much emphasis in our state's firefighter 1&2 programs on topside ventilation it seemed to become a check box on every job. I can't count how many useless holes were cut after the fire was under control. Due to the contact hours required to ensure a rookies safety in carrying out this task, as a tactic it rose to the level of direct fire attack. No doubt a very important tactic, but like every other tactic, time and place is critical and if we don't understand these, we waste resources at best, spread fire and hurt people at worst. We are learning more than ever about true ventilation and how modern construction really can help or hurt our efforts.