May-June 2009 Issue

	May-June 2009

A Story and a Half

By Brian Smith

In this article, I would like to describe the issues that can arise when trying to fight a fire in a building that is sometimes referred to as "a story and a half."

Some time ago, my engine company was dispatched to a structure fire on 19th Street. There was a delay in our response due to some confusion over a wrong turn. The first-due engine arrived on the scene and reported a working fire on the exterior of the structure. The officer began to give out assignments, including the water-supply order for my engine. Shortly thereafter, he told all units that the fire was under control and that everybody could return to quarters. We were close by and decided to go on scene. It was on the way back to the station, anyway. As we walked to the rear of the structure, we noticed smoke issuing from the eaves. Not only was it coming out of the eaves on the Baker-side, it was coming out of the gutter downspout under pressure.

"E1 to Command." "Go ahead E1." "Command, we have an attic fire." And indeed we had an attic fire in a "story and a half" residence.

Because of this fire, I became more educated to “story and a half” construction, the challenges it presents to extinguishing hidden fire, and how and where to open hidden spaces for complete extinguishment. Using lessons learned from the 19th Street fire and with photos taken from a recent fire in a similar type of house, this article will describe the construction type and appropriate tactics.

First of all, let’s all get on the same page and define what I mean by a “story and a half” construction. When a first-in officer gives the initial description as a wood-framed, 1½-story residence, this is what the rest of the assignment should imagine (see photo below).

The difference between this occupancy and a two-story occupancy is that a living area has been built into an existing attic space. You can also have a 2½-story residence:

Frankly, a similar situation is possible in a commercial occupancy when living or storage spaces are built into the roof structure. We have a warehouse just outside of my first-in district that has an arched truss roof and multiple occupancies where the second floor is built into the truss area. It may be termed a mezzanine level. So why is it so important to understand the difference between a "story and a half" and a second-story when it is stated in a size-up? The nugget here is the understanding that the "story and a half" construction creates hidden spaces that must be opened and exposed to find and check for the extension of any fire. With involvement in the concealed spaces, it is important to consider that the fire may be destroying the structural integrity of the occupancy. Without this insight, you will not stand a chance of getting ahead of the fire, wasting effort in opening areas or ventilating areas that will not help the cause.

At the 19th Street fire, the first-due company reported an exterior fire that they extinguished. As my crew from Engine 1 walked to the B-side, we found evidence of an attic fire with heavy smoke under pressure pushing from the eaves of the structure. This is the worst-case scenario for a "story and a half" structure, when a fire below the attic area or an exterior fire extends into the attic’s concealed spaces. In my opinion, attic fires are one of the most difficult with which to be successful because of the difficulty in accessing the concealed spaces. Generally the best way to expose an attic fire for extinguishment is by vertically ventilating and pulling ceilings.

In a "story and a half" structure, the attic area potentially has three concealed spaces. See the photo below.

When the homeowner or builder decides to create a living space in an attic, they build two new walls called knee walls. They are not full-height walls, and if the siding was off the exterior walls of this structure, you would see the studs to the right and left of the window connected at the top to the rafters of the roof via a sill plate. These knee walls create two lower concealed spaces that travel (in the following photo) from the front to the back of the house. Most homeowners use this space for storage. Most, but not all, "story and a half"-type houses will also have a third “upper” attic space created when the builder puts in a ceiling to the living space. There are some rooms that have vaulted ceilings, thus avoiding the “upper” attic space.

This photo illustrates the knee wall and how it transitions into the sloping ceiling. This is a room that took up half the attic space (the other half being concealed) in a house that another shift responded to for a fire. This knee wall will require the center of attention.

This photo shows the opposite-side knee wall opened up. You can clearly see the size of the hidden space and understand the potential fire load (both the unprotected structural members and any combustible storage material) that is available. This space is connected via channels created by the rafters to the upper attic, as shown in the photo below.

The connections of these hidden spaces are usually not fire-stopped and whether the building is ballooned framed or not, fire will spread both laterally and horizontally. It is a priority to identify the structure as “story and a half” so that crews will know that multiple hidden spaces will need to be opened.

In reviewing the 19th Street fire, we identified the attic fire; and the chief requested responding units to return.

An engine company was directed to the interior with pike poles and a hoseline. Following the age-old method of pulling ceilings to access an attic fire, the officer in charge of the interior directed that a hole be opened in the ceiling. Nice call in a conventionally constructed two-story house, but it was not the right thing to do in a "story and a half." As soon as a hole, no bigger than a basketball, was opened, smoke poured out. The room went to zero visibility in about 30 seconds. A problem was encountered when it was discovered that the homeowner had built a ceiling over an existing ceiling. The drywall ceiling gave way to one that was tongue and groove. All that we had accessed was a small space full of heated and pressurized smoke. We retreated to the first floor to fall back on Plan B, which was no more successful than Plan A.

LESSON LEARNED

The center of gravity (to borrow a military term) of a "story and a half"-type construction is the knee wall. It is imperative it is opened to cut off an extending attic fire. Our first order of business should have been to open the roof, then the knee wall on the side of the original exterior fire. With ventilation of the living space to maintain visibility and relieve the building of heat and gases, fire extension would have been checked. The exterior fire gained access to the attic via the eaves that overhung the street side deck. By opening up the ceiling first, we did nothing to aid our cause — only complicated interior conditions. Once the first knee wall was opened and fire extinguished, the ceiling and the opposite knee wall should have been opened to assure the fire had not extended further. The knee wall is the collection point for extending fire. Exposing the area behind the knee wall cuts off fire from below, while application of water will allow steam to work its magic for any fire that has extended above. Again, all areas must be overhauled to assure complete extinguishment as the crews did to the "story and a half" structure below. Because they are concealed spaces and avenues for fire spread, knee walls should always be opened and checked especially when fire has involved the upstairs living space.

The final piece of this puzzle is to discuss some common pitfalls or issues that can arise in fighting a fire in this type of construction. Knee walls are not always easy to access, especially if the attic is fully pressurized and concealed spaces significantly involved. The living space will become an oven, actually a convection oven, because you would be surrounded (top and four sides of the room) by the heat of the fire. Descriptions from some firefighters who braved this condition indicated that the living space was almost totally clear of smoke but could see the heat waves shimmering in the air of the room. An appropriate tactic would be to vertically ventilate the attic space and the living area to provide some relief to the interior crew so that they can begin to open up the knee walls and the upper attic space.

If fire has possession of the first floor and will not allow crews to enter in order to open the knee walls, consider opening the upper and lower concealed spaces from a gable end of the building. This was successfully accomplished at the structure fire in the photo below.

In conclusion, I hope that my story will help you the next time that you are faced with a fire in this type of construction. As an aside, I went to 19th Street the other day to take a photo of the house in question for this article. It wasn’t there. I assume that we did such a good job at this fire that the owners bulldozed it and sold the lot to the highest bidder.

REVIEW

A thorough knowledge of building construction is critical. Train your firefighters to understand the location and importance of opening hidden spaces found in various types of construction.
When reporting on-scene, properly identify the structure. If it is a "story and half," remember that “center of gravity,” the knee wall. Hit it early and hard.
If you can’t get at it directly, cut holes in the gable end for access. Avoid unnecessary holes that do not access the knee wall or do not provide ventilation, they are a waste of time.
Overhaul of the structure must be complete and thorough.

Good luck at the next fire you have, and remember to expose those spaces. Thanks for letting me tell “A Story and a Half.”

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