The Roundtable: Lightweight Wood-Frame Mixed Occupancies

What Are Your SOPs and Lessons Learned?

(Qasim Pr, YouTube)

Bobby Halton and Bill Carey

Across America we have been witnessing the construction of lightweight wood frame multiple family mixed occupancy buildings. The first floors are fire resistive or noncombustible and have offices, business, and parking garages or some combination of the sort. Fires have occurred under construction and after completion. These events tax the resources and capabilities of the agencies responding. What SOP’s guidelines, preparations or experiences and lessons learned can you share regarding these structures?

Lightweight Wood-Frame Mixed Occupancies: What Are Your SOPs and Lessons Learned?

Read Part 2 Responses

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Note: Due to the overwhelming response, this will be a two-part roundtable

Dustin Martinez

In our agency, the lightweight wood-framed mixed occupancy has become the almost preferred construction type for the uptick in multi-family dwellings. With the land becoming more of a premium in our areas surrounding both the college and Truest Park baseball stadium, we have seen an onslaught of these buildings. The need to build vertically with the convenience and luxuries of the business below, our department has had to adapt not only operationally, but our apparatus have changed to reflect these buildings.

For our engine operations, due to the nature of some of the stretches and setbacks, the rear engines of our hose beds have changed to accommodate the required mobility and speed of the initial stretch. A 500’ bulk load was placed on the rear, consisting of 200’ of 2 ½ inch hose below 300 feet of 1 ¾ inch hose with a 7/8 inch tip. A one hundred foot minute man bundle finishes the load to allow for the nozzle firefighter to keep their working length on the shoulder and forward advance the additional 1 ¾ as the ascend stairways and obstacles until they reached a desired point to flake out. Depending on the difficulty and severity of the stretch, the heel firefighter or officer (depending on staffing) is accountable for assisting with the remaining 2 ½ hose to rapidly get the initial line in place.

Our second static load off the rear is 400 feet of 2 ½ inch line for the option if more hose is needed for the initial line, or the second due apparatus needs to stretch an additional line. Crews arrive with their bundle off their bulk load and deploy the line as needed. We also removed our 1 ¾ high-rise packs in favor of the 2 ½ standpipe bundles to address both the adequate flows for pre-1993 standpipe buildings as well as a required standpipe hookup when encountering the higher floor operations on these buildings.

Finally, we began purchasing and outfitting tractor drawn aerials and placing them in the territories that typically would respond to these occupancies. The concern arose not only for the more difficult access for some charlie side operations, we also encountered some buildings placing parking decks in the rear hindering aerials entirely. Our tillers also brought in the ability for 45-foot ladders that we previously didn’t outfit in the department allowing access to some of the upper floors for immediate rescue or egress measures.

As these buildings are more rapidly ascending, the only way that we can truly be prepared for these incidents we may encounter is individual crews pre-planning their territories. Through training and drills, they become familiar with the stretch and access difficulties as well as the most efficient way to combat them. In the words of Napoleon, “Nothing succeeds in war except in consequence of a well-prepared plan”.

Robin Nicoson

We really start with the lessons learned because the problem isn’t lightweight construction. The problem is what happens when lightweight construction is exposed to fire. So first we must continue to educate on lightweight construction and how it uses “engineered lumber.” This is a term that is generally used to describe a wood structural member that is fabricated through use of bonded fibers and different materials and then it is usually put together as a joist or beam. And we know through our own experiences and prior lessons learned  that lightweight, wood-frame buildings burn extremely fast and hot.  When this fire exits the room of origin more generally it will then vent to the outside of the structure, spread upward, and could evidently burn through to the truss. Lessons learned have taught us we may experience collapse in less than five minutes on a truss and up to 16 minutes on flame impingement on a gusset plate.  These lessons have taught us that the game clock has been greatly shortened for us to be successful.

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Besides having those prior lessons learned and the education of building construction we must understand how today more than ever the smoke and fire conditions help determine our tactics.  The tactics we were taught years ago might and will need to be modified.  Being aggressive with primary and secondary searches,  fighting fires from the interior, ventilating, opening void spaces, and property conversation are all sound tactics that are still used daily.  The difference is in how we employ these tactics for lightweight structures.  Correctly reading the smoke/fire conditions provides us the time and ability to enter and search, how and where we vent, the time and ability to attack from the interior, and where the fire will go. We must stay and be aggressive in our actions to save lives and property, but today with light weight construction we must align the time factor with our strategy and then tactics.

So using all this information we established different systems and communication keys. The first document is a verbal prompt which comes from the communications center to our fireground commanders. This document shows the communicator how the timing process effects our success. The second document is used when we have a structure that is compromised, especially lightweight, that our communications center provides our IC.

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Eddie Buchanan

We experienced a large fire in this type of occupancy in our metro area back in March of 2004.  Departments from all across the region responded to assist the City of Richmond Fire Department for that incident.  The key lesson from fires like this is that few departments in the U.S. can handle such an incident alone.  You’ll need to be able to fight fire side by side with firefighters from around your region.  

Since 2004, much has been done in the Richmond Metro Area to build relationships and interoperability among the fire departments.  A regional high rise procedure is now in place; along with regional procedures for firefighter accountability & maydays, big box fires, and highway incident safety.  Also, departments have gone to a regional unit numbering system that allows departments from multiple jurisdictions to operate on the same fireground seamlessly via a region-wide interoperable radio system.   Responding units can simply switch to another locality’s tactical channels and blend right in with operations.  We have had multiple occasions to test these capabilities as a region and they work incredibly well.  

Builders and localities seem intent on building more of these structures and we are seeing them burn in a big way more often.  I think it’s important for fire departments to consider a regional approach to such large scale operations and work to develop the procedures and operational systems necessary to quickly ramp up for a big incident. Unless you’re in a large city like New York or Los Angeles, you’re going to need help from your neighbors to fight these types of fires.

Jim Crawford

Here is my two cents thanks to the feedback from my friends Stephen Hrustich — Project Manager for Vision 20/20, and Sean DeCrane with UL.  There is an active role for code adoption and enforcement in construction that features lightweight wood construction.  We can expect to see much more of it in the future. 

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Wood as a sustainable product, and because it is less expensive.  The concept is sacrilege for many in the fire safety world because of the inherent danger in this construction type — but also because fires in these situations during construction seem to be occurring far more often.

Fire sprinklers can help of course — but not until they are installed and operating.  When I was Fire Marshal in Portland Oregon (many years ago in a galaxy far, far away) we had a 10 million dollar fire loss from an apartment building in downtown — using (then) new wood construction concepts.  NFPA also has a standard devoted to safety during construction (NFPA 241).

I would urge readers to consider investigating these solutions — and have provided a case example from Stephen when he was in Gwinnett County, Georgia — as a reference.

Lane Woolery

This style building has been built in ever increasing numbers in our city as the population and density has increased. We handle them with a standard Commercial Fire assignment of four engines and two trucks. As they are all fully sprinklered, they have not proven to be a major fire problem for us. Mostly just smoke and water removal. They have proven to be a reasonably safe way to achieve the housing densities our community requires. Far safer from a life safety standpoint than the two- to four-story center hallway type apartments many of these buildings replaced.

Bill Gustin

Floors supported by lightweight wood parallel chord trusses is the “balloon frame construction of the 21st century; just laid on its side.   Often the occupants of these buildings are protected by an NFPA 13-R-residential sprinkler system.  Notice I didn’t say that the building is protected by sprinklers  because it isn’t. 

A fundamental flaw in 13-R systems is that there are no sprinklers in combustible void spaces, most notably  the attic and interstitial spaces between ceilings and floors.  A fire that originates or extends to a void space can take possession  of the building with a 13- R system.  Fire burning in a floor truss void space will quickly become ventilation limited until we start pulling ceilings which has the effect of opening a damper on a wood burning stove. 

Why don’t we keep fire in floor truss voids fuel-rich by not opening the ceiling; rather use a piercing nozzles?   When searching for and attempting to get ahead of a fire running the floors,  penetrate the ceiling with a piercing nozzle and flow it .  If there is no steam conversion, no harm, no foul, just move on to another spot and try it again.  In some jurisdictions draft stopping is required in the floor truss voids separating units and the public hallway or every 2500 sq. ft.  If you don’t find fire in the floors, you may be on the wrong side of draft stopping. 

Note: Responses are solely the opinion and views of the individual and have only been edited for grammatical reasons.

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