Everything so far has been description. This lesson is the method. The goal is to stand in front of a building you have never entered and, in about a minute, make a defensible prediction about how a fire in it would behave and how long the structure would hold. That is a real skill and it is also a modest one, so let us be honest about both. It will not tell you what is behind the drywall. It will narrow the possibilities enough to change what you do first, which is all any prediction has to do. The method is five steps in a fixed order, plus four details that carry more weight than the rest, plus a discipline about how firmly to hold the conclusion. That last part is not a caveat tacked on the end. It is the part that keeps the method from becoming a liability.

Three objectives. First, you should be able to run a structured read of an unfamiliar building, in order, without needing to remember which lesson each piece came from. Second, you should be able to state what you do not know as clearly as what you do, because a read that does not distinguish between the two is worse than no read at all. Third, you should be able to record it so somebody else can use it, which in practice means pre-incident planning: the read you do once, calmly, in daylight, is worth ten done under pressure. If you can do those three, this class has done its job, and the previous five lessons are the reference material behind them.

Five steps, in this order, because each one narrows the next. One: era. Estimate when it was built, because era drives framing, and framing drives everything in lessons two and three. Two: type. Place it in the five construction types from lesson four, which tells you what the structure is made of and how it will fail. Three: spans and voids. Look at the width of the building, the openings, and the roofline, and ask what has to be carrying that span and where the vertical paths are. Four: alterations. Look for what has changed since it was built, since every addition, re-siding, conversion and new storefront is a place where your era estimate stops applying. Five: occupancy and load. Ask who is in it, when, and what they have put in it, because the contents are the fuel and lesson five is about how much that now matters. Era, type, spans and voids, alterations, occupancy. In that order.

Some exterior details are worth far more than others, and four of them tell you most of what you can get for free. Window proportions and floor-to-floor heights, because tall narrow openings and generous storey heights point to the older balloon-framed stock. The roofline, because a very shallow pitch on a wide span usually means a lightweight truss, and a complex or altered roof means a renovation you cannot see inside. The foundation and how the building meets the ground, since a raised first floor over full-height masonry is characteristic of one era and a slab is characteristic of another. And the party walls and the gap between buildings, because attached buildings raise the question of continuous attics and cocklofts, which is the most lethal single feature in ordinary construction. Four details, thirty seconds, and you have narrowed both the framing and the failure mode.

One caution to close on, and it matters more than any individual technique. A read is a prediction, not a survey. It is built entirely on what you can see from outside, and buildings are routinely altered in ways that are invisible from the street: cavities opened and left open, a truss roof put over conventional framing, a party wall breached for a doorway, a floor system replaced. So hold the read firmly enough to act on and loosely enough to abandon. Practically that means two habits. State the read out loud, including the uncertainty, so that everyone is working from the same assumption and knows it is an assumption. And name in advance the observation that would overturn it, because a prediction you cannot imagine being wrong is not a prediction, it is a commitment. The read is a starting hypothesis. The building always gets the final word.

The whole class in three lines. The building chooses the path, so a fire's route is an inventory of the openings and cavities the builder left rather than anything the fire decided. Mass buys time and warning, and thin engineered assemblies buy neither, so the age and the weight of what is holding the floor up tells you how long you have and whether you will be told before it goes. And the modern interior gives you far less time than any figure you inherited, with roughly three and a half minutes to flashover where the older number was closer to twenty-nine. If you remember only those three, you can reason your way to most of the rest.

If you want to go further, these are the places to go, and between them they cover the research, the classification, and the practical training. Look for the full-scale fire dynamics research first, because that is where the numbers in this class come from and seeing the tests changes how the figures land. Then the construction and classification references, for the detail on types, assemblies and rated construction that we compressed into single slides here. And then whatever hands-on training is available to you locally, because reading a building is a perishable skill that improves by doing it out loud with somebody who will disagree with you. One suggestion on order: watch a flashover test before you read anything else, because it makes the rest concrete.

That is the class. Do one thing with it this week. Pick a building you pass every day, one you have walked past hundreds of times without looking at, and read it properly. Era, type, spans and voids, alterations, occupancy. Say your conclusion out loud, including what you are unsure about, and name the observation that would change your mind. Then do it again next week with a different building. The method only becomes useful once it is a habit, and it only becomes a habit if you practise it when nothing is on fire. Thank you for taking this class. The buildings on your street have been telling you this the whole time. From here on you can hear them.