Hey there, I’m Stewart, an architecture professor and designer. Its the beginning
of summertime here in the midwestern united states and I’ve travelled all the way up
from Chicago to a cabin in northern Michigan to practice my fire-making skills. You see,
fire is an important part of architectural design. And in this video, I’m going to
walk through how to make a fire like an architect, and offer some poignant architectural examples
of how fire shapes the design of buildings in general so stay tuned!
Fire is an often overlooked but essential driver for the design of buildings. People
like the theorist Gottfried Semper even argued that fire is what spawned the beginning of
architecture and even the beginning of society itself. People would gather around a fire
and it thus becomes the central space for community and gathering. It offers a certain
amount of thermal protection for the group. Then the fire and group needed additional
layers of protection which was provided through constructing shelter which in turn becomes
architecture.
In addition to providing social gathering and thermal regulation, fire is also important
to cooking which is an essential domestic activity. As we shifted from nomadic to agricultural
societies fire was a central feature in houses. However, over time, with technical advancements,
the fire eventually moved toward the edge of the home, where it could be exhausted more
easily. Until finally today where fireplaces are seen more as luxury item than a necessity.
It mostly provides an aesthetic experience than a true functional performance in most
cases.
However, even today fire shapes the spaces in buildings in direct and indirect ways.
Fire codes govern everything from the sizes of buildings, to the configurations of rooms,
to the materials we use and how they’re assembled. We even have fires burning even
while we can’t see them, pilot lights, or the little blue flame burns in our furnaces
and boilers hidden away and ready for when we need heat.
But, right now my task is to chop some wood into various sizes to construct this evening’s
campfire.
Step 1: Chop some wood. Small pieces and larger ones.
Wood is an extremely popular material for construction, especially here in the United
States. Its strong, plentiful, renewable, and doesn’t require a ton of expertise to
make buildings from it.
Wood construction can take many forms. Of course entire logs can be stacked to form
log cabins. Here the wood is used more like masonry. We don’t really have the resources
to use this materially intensive method of construction anymore, so we cut wood down
for use as frames. Depending on the size and spacing of these frames, we might have light
wood framing like with 2x4’s, or timber framing. Because wood is so flammable its
use is very specific and regulated in the building industry.
Because wood framing is so flammable it has historically been limited to smaller buildings,
especially homes. However, more recently, with chemical treatments, supplementary fire
suppression systems, and other innovations, multistory housing made of wood framing has
become possible.
Further, other wood products like Cross Laminated Timber have even led to skyscraper designs
made primarily out of wood. In these buildings, fire is an important design determinate to
ensure the safety of the inhabitants.
Step 2: Wheel over to the firepit Gather some little sticks along the way.
Fire codes are really determined by three main factors, building size, program or use,
and the materials used in construction. All of these factor into how many people will
need to be evacuated in the event of a fire, and how much time they have to do so. There
are a number of model codes that are referenced and adopted by various jurisdictions and The
National Fire Protection Association (NFPA) is charged with setting standards for fire
prevention and other life-saving emergency endeavors.
These codes developed over time in response to various fire events and are written with
the goal of providing reasonable protection of life and property from the hazards of fire
and explosive materials. Fire codes exist to minimize hazards to life and property from
fire and panic.
On our way to
the firepit, we need to grab small twigs to serve as starter fuel for our fire.
Step 3: lay the first layer. My fire-building technique is called the log
cabin method or criss cross fire, which relies on stacking the wood in a square of alternating
layers. You start with the unchopped logs as the foundation. It’s high enough to allow
for the kindling in the center and these logs burn very slowly to maintain the integrity
of the fire for as long as possible. These work much the same way that timber framing
works in buildings.
Timber framing has a unique way of burning that actually makes it perform quite well
during a fire. Due to the large size of the units, the outside burns first, which forms
a crust of burnt charcoal that is no longer directly flammable. This crust allows the
timber to retain its structural capacity for quite some time becoming almost fireproof
in the process.
Step 4: Lay the second and third layers. Now is the point
where we start to stack the rest of the wood. Here we need to make sure of a couple factors.
Firstly, we go from largest pieces of wood at the bottom to the smallest at the top.
The cut face needs to face the interior of the fire so as to catch fire first. Also,
we should be stacking in such a way so the upper members are offset to the interior of
the ones below. All of this sets up a condition where the upper ones will catch fire simultaneously
with the ones below but burn off the quickest. The entire assembly also collapses inward
in a predictable manner.
Design for fire in buildings follows similar lines of thinking. It’s not necessarily
about making buildings fireproof, although some are, its about controlling the method
of burning to slow it down, prevent it from spreading, and keep people safe while they
evacuate and fight the fire. Basically to control the fire so that it can be predictable.
With wood stud framing, we rely on the wall assembly to provide protection. The sandwich
of materials is given a fire-rating which is an interval of time. A typical interior
wall of 2x4 studs sandwiched between layers of drywall isn’t usually rated, but might
last 30 minutes in a fire. At critical barriers between spaces, like around stairwells or
between buildings, the code might call for a 1 hour or 2 hour fire rating which means
it can resist the exposure of a standardized fire exposure for one or two hours. This can
be achieved through a number of factors including layering up the drywall, which is more fire-resistant
or using fire-resistant treatments and coatings.
Step 5: Light Now is the time for lighting the fire, which
happens at the base of our setup. If performed correctly, the design allows you to easily
light the fire from the outside of our cabin construction. The construction should also
provids protection from strong winds while the fire builds. But, at the same time, allows
for sufficient and directed air flow to feed the fire oxygen. The large logs at the bottom
allow for air to be sucked under and then when heated rise through the top of the wood
creating section and lanes of flow.
There are couple of principles in action here, one of the most important is Bernoulli's principle
which talks about wind speed differences to move air. ... Architecturally speaking, outdoor
air farther from the ground is less obstructed, so it moves faster than lower air, and thus
has lower pressure. This lower pressure can help suck fresh air through the fire or the
building.
This can be useful if we’re talking about gentle breezes through a building, but where
fire is concerned we need to prevent this accelerated air flow which can spread fire.
Fireblocking is the term for barriers between floors and between a top story and roof or
attic space, and is used to slow the passage of flames and hot gases through a structure.
According to IBC Section 717.2, fireblocking is required in combustible construction to
cut off vertical and horizontal concealed draft openings.
Fireblocking is related to but different from draftstopping, which prevents the flow of
hot air and smoke through a structure. It is used to subdivide floor/ceiling assemblies
according to IBC Sections 717.3 and 717.4. Draftstopping is installed so that horizontal
floor areas do not exceed 1,000 square feet, and attics or concealed roof spaces are 3,000
square feet or less. Therefore, it is installed in dropped ceilings, plated floor trusses
and roof framing.
Step 6: Let it go. Finally we are able to enjoy our
fire and if everything goes according to plan it will burn for over an hour without much
maintenance. It will burn quite hot and completely. When you’re through, have a 5 gallon bucket
handy, dip into your nearby lake and douse it until it no longer smokes.
Of course, buildings can have fire suppression systems in them as well. Using water pumped
through a sprinkler system is the most common. However, it’s also not the most effective
kind of suppression system for every circumstance. In some instances, water can be more dangerous
in the presence of certain types of fires than other available extinguishing agents.
It can also cause extensive damage to your property or equipment, requiring substantial
cleanup.
There are other options if those drawbacks are too much for you. You can use chemical
and gaseous fire suppressents. Inert gasses work to smother fire by displacing the oxygen
in the room. This is useful for rooms with sensitive equipment. Carbon dioxide systems
are also possible but could be harmful to inhabitants, so it should be limited to unoccupied
areas of the building.
Chemical cleaning agent systems are like the inert gas systems in that they also discharge
and disperse out a gas. They provide extinguishment through heat absorption and leave no residue,
which means no additional equipment damage. These fire suppression systems are less hardware
intensive and cost less for installation.
While I’m enjoying this fire I want to thank you all for watching. If you enjoyed this
video, if it made you feel all warm inside, please consider giving it a thumbs up. You
might also enjoy a video I made on the professional development lessons one can learn from the
movie indecent proposal or the one on how all good architecture leaks. Leave a comment
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That’s all for now. See you all next time!