The Chicago Lumberyard

Rear Porch Fires

Chris Tobin

Go to any large Midwestern city and take a drive down an alley, what you’ll see is an architectural feature colloquially known as the “Chicago Lumberyard”. A term that reflects the prevalence of rear multi level wooden porches extending as far as the blocks they’re built in. The wooden alley porches you see today were commonly built between 1900-1940 out of functionality more than convenience.  Some offered stairs doubling as fire escapes while some did not. Before modern air conditioning, open porches offered relief during the oppressive humidity of Midwestern summers. The only other option was sleeping outside or in parks. Another common function of rear porches was a place for wood stoves and kerosene heating which just added to an increased fire hazard. Porches were naturally built off of the kitchen which allowed for easy access of fuel delivery for cooking as well as ice for those who could afford it. 

Today’s rear porches come in two types, open with handrails and fully enclosed framed with windows. Most do not have porch stairs and may instead have a rear stairwell on the first floor accessed through a back door, especially in four family flats. Treated pine is the most common construction material due to its rot resistance, but over time structural integrity is slowly comprised. Modern uses of rear porches can vary greatly from social gathering places, storage, office space, and bedrooms. Typically vinyl siding has been added over the older exterior which can be anything from asbestos siding shingles to era wood siding. All these will require aggressive truck work to overhaul working concurrently with fire attack. Another feature is that the basement stairs are typically right under the 1st floor porch, so don’t automatically assume a porch fire started on the porch. Be sure to rule out a basement fire extending upward on arrival with an effective 360 size up. 

Tactical considerations are similar to the principles of exposure protection since rear porches in Type lll’s will be separated by the rear brick wall. This offers a level of protection from fire spread into the cockloft, but enclosed porches are often stacked combustible construction. So you have rapid exterior fire spread to every level of the building from one source, which can extend horizontally into the dwelling on multiple levels at once. Life safety is the number one priority, especially potential victims that may be trapped above the 1st floor. Hose lines must be stretched to the proper location the first time saving costly delays in repositioning. There are many options for deployment depending on your resources and conditions. 

The basic strategy here is confinement by holding the rear wall, thus keeping the fire out of the main building while searches are conducted. Since porches are in the rear you have to weigh your options when deploying hose lines. Is stretching down the gangway for exterior application going to be quicker than forcing entry with an uncharged line to an upper floor? Does an engine company respond to the rear? How about tandem lines? One goes inside to stop horizontal extension, and one to the rear to stop vertical extension lapping upwards to the roofing material additionally available to protect adjacent exposures. Traditionally the first line went to the fire floor and the second went to the floor above. All these have to be considered. If people are reported trapped the first line must go inside and hold extension at the rear wall putting water in between tenable spaces supporting a rescue effort. If there are rear interior stairs those have to be protected as well. 

If your staffing is unable to stretch multiple lines quickly and must rely on only one, err on the side of probability and make entry knowing most porch fires start on the inside and typically have no doors to slow fire spread. Tenable space must be claimed early on and with expedience. Any fire attack that starts outside must have the manpower and second line ready for almost concurrent entry or you risk delaying actual extinguishment of interior spaces for exterior ones that pose less threat to valuable property and possible victims inside. Additionally re-stretching and repositioning a charged line back to the front and possibly up stairs is extremely laborious, even more so in an already understaffed situation. 

 Interior operations need to be cognizant of the transition between the legacy floor of the main building and lighter weight decking of a porch. The collapse potential increases with porches made of modern floor decking such as plywood covered in tile which presents a “terrazzo floor” effect. Weight is also a factor due to aging structural supports not originally designed for a fully framed room with contents. It’s not uncommon to find holes burned through right inside the porch entryway. Anyone advancing the nozzle shouldn’t enter a porch if they can’t assess its integrity. Sounding the floor decking with your heel of your outstretched foot or a hand tool is paramount. Let the stream do the work until visibility increases and operate from the building side of the rear wall if the floor is comprised. 

Master stream options are limited to rear accessible areas such as alleys. If obstructions are present like light poles, wires or overgrown brush and trees a 2.5 hand line will be optimal. A portable monitor device stretched to the rear is also a choice for well off fires with exposures. Exposure protection will also be the most effective from the rear instead of trying to operate from the front down gangways that diminish your stream angles. A quick stretch to the rear with a second or third attack line should be considered. Exposures are common place with rear porches, so expect one on each side especially if wind conditions exist. 

Roof ops can assist by keeping vent holes near the rear and checking the rear wall by pulling back the flashing or tar paper for any extension into the cockloft. The objective is holding or limiting fire extension to the porch side of the rear exterior wall on the original building. Horizontal extension into the cockloft or attics is number one. Guttering should be pried off in the rear to expose the layers of decking and roofing materials during overhaul. Additionally, some rear porches have scuttle openings on the top floor porch roof making vertical ventilation that much easier. A trick is to open the scuttle and force the apron wall inside for quick access into the cockloft. Careful not to unknowingly operate above a porch which is inherently weaker than the roof decking of the original building. Some are tarred over in a way it’s difficult to notice any transition. The parapet side walls will give you a clear indication of where the back wall terminates and the porch roof starts. Pull back some coping stones and make continuous checks for horizontal fire extension into the main building. Any extension found should be immediately communicated with the IC and coordinated with crews below. 

These are just a few basic principles to guide by, but there are many more out there worth knowing. The main thing to remember is what inherent issues your building stock presents regarding rear porches.  Become intimately familiar with your working environments using every non fire related run as one more opportunity to preplan for the fire related one.