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THE MILWAUKEE METHOD = A panacea for all steep pitched roof operations?

First of all, let me be clear that this is not an indictment of the method itself. You will not read any dispute or argument here against its effectiveness and rapidity. Nope, it’s good alright. A solid ventilation operation was born out of the necessity and a belief in the importance of peaked roof ventilation. These firefighters developed, evolved, and refined a vertical ventilation method that accomplishes the tactical requirements and at the same time keeps the brothers on solid working platforms in case things go bad. On the contrary, maybe it’s too good, too fast, and too easy! So much so that firefighters that don’t study their first due areas and the changing construction within them might be setting themselves up for a failure of the worst kind. The question I pose is whether or not this roof operation has evolved enough? Anyone that knows me is well aware of my proclivity towards and general belief in the value of topside ventilation and roof operations as a whole in relation to overall incident success. However, today’s disconcerting matrimony of internet videos and a chronic malaise towards truly educating ourselves on the ever changing arena in which we do battle has led to an increased reliance on Band-Aid cure all’s to real first due challenges. Without replicating, matching, and ultimately testing these methods in and on the buildings that you respond to you could be placing yourself and your company into a high risk scenario without even realizing it. A review of the method would be prudent prior to continuing this conversation. You can find the video of the operation under the Fire Engineering Training Minutes Truck Company section.

http://www.fireengineering.com/topics/m/video/68422572/milwaukee-me...  

So what am I yammering on about? Well hopefully you all just reacquainted yourselves with the method so that we can get into the guts of the operation. The portion of the video that peaks my interest plays from the 2:15 mark to the 2:30 mark. You see I respond to and perform my topside vent operations in a city with a predominant amount of pre-engineered, lightweight trussed roofs. And, this concern of mine stems from a very distinct structural design or lack thereof. Where a conventional rafter or even older legacy roof system derives its strength and general load carrying capability from the rafters resting across the outer load bearing walls and joining in the middle at the ridge beam; the lightweight, pre-engineered truss system does not. What’s a ridge beam? A ridge beam or ridge pole as it is also called, is simply a piece of dimensional lumber that is hung and supported from gable to gable or bearing wall to bearing wall. The roof rafters were then miter cut, nailed to the ridge board and laid across the outer load bearing wall. A collar beam would then connect the rafters from the C-side of the roof to the rafters from the A-side of the roof thus adding to the roofs overall stability and rigidity. Load carrying capacity is derived from the dimensions and on center spacing of these roof rafters. This “Cut and Stack” style of roof construction was utilized up until the mid to the late 1960s give or take, depending on your part of the country. The lightweight roof system followed next with several generations of truss construction. Lightweight construction is made up of pre-engineered trusses that are built off site and then trucked to the site. Once there, they are hung in place at 24” intervals and a “filler” or “stiffener” stud (2”x 4” or 2”x 6”) is toenailed in between each truss at the peak or highest point of the ridge. This along with the plywood or O.S.B. attached using “diaphragm nailing” techniques provides resistance to “shear” force (namely wind) and any other lateral movements that might cause the trusses to fall over like dominos. The absence of a true ridge beam is kind of a big deal when discussing roof operations on a burning building, especially when the Milwaukee operation is 100% reliant upon the strength of said ridge! It seems everyone has lightweight trussed roofs in varying amounts. And, in case you were wondering, yes they can engineer steep pitched roofs using pre-engineered trusses.  One just needs to Google Image Cathedral Truss or examine the attached pics. Yet in their operation there is no sounding or diagnostics performed prior to ascending and straddling the ridge to set the ladder. I never read or hear anybody throw out an F.S.A. (firefighter service announcement) regarding this method, "warning, not intended for use on pre-engineered trussed roofs".  Again, the problem does not lie in the operation, the problem lies with our firefighters. Much like the need to add the “I“ to the acronym V.E.S. arose out of the always present human factor. The same issue is present here. We all know how much firefighters love systematic, step by step operations that spell out how to accomplish an otherwise precarious tactic on the fire ground. A system that takes the thinking out of it for us! The reason I chose the Milwaukee method to examine is because of its popularity. This operation is now all over the web and has been replicated on several other popular websites. We need to ensure that we understand the differences in building construction and their performances under fire conditions. While this is an outstandingly efficient operation for steep pitched roof ventilation, we must comprehend and appreciate the risk with performing this or any other type of roof ladder operation on a pre-engineered, lightweight trussed roof. If a steep pitched roof needs to be cut and your truck was not able to get the address, then roof ladders it is. Just make darn sure that you perform your diagnostics on the way up and do your best at sounding this roof prior to committing yourself to it and basing your safety solely on the expectation of a ridge beam which might not be there in the first place. On a lightweight system, when possible, using the security of an aerial ladder or platform may be a more reliable option depending on the time it takes for deployment. It is imperative that we become thinking firefighters who are not afraid to ask questions and who understand building constructions generational differences and the impact of the fire and the work that must be performed has on them.

                                      Below is a pic of a Cathedral Truss prior to ridge stiffener installation.

 

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Left and below are pics of a conventional rafter system with an

obvious "true" ridge beam.

Below is a pic of lightweight, pre-engineered trusses being set and hung prior to the 2"x 4" stiffeners being installed.

Below is a pic of an attic fire in a Lightweight, pre-engineered truss assembly. You can see the 2" x 4" stiffeners in place and how their placement at the ridge positions them in the prime location to sustain the bulk of the fire damage.

 

Below is a pic of a diagnostic cut. This cut can undress the entire roof system and only takes seconds to accomplish with a chainsaw. Smoke & fire conditions, construction type & direction, decking, covering type & thickness will all be identified in 8 to 10 seconds. Spend the time to increase the chances of a successful operation.


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Comment by Colin Kelley on October 1, 2013 at 5:46pm

Just an example of one variation using engineered I-beams.They can use these I-beams and miter the ends to whatever rise or pitch they want. 

Comment by Colin Kelley on October 1, 2013 at 5:43pm

David, apologies on the delay in the response to your post. I was out of town on vacation. I would like to thank you for taking the time to respond to this blog. It was most assuredly a pleasant surprise! Who better to bounce my thoughts and opinions off of than the man himself! I will try to respond to your cited rebuttals in the same way that you did. I want to make myself very, very, clear that in no way am I arguing against the method that you or whoever within your organization has developed and fostered. I am a huge fan of it! I only wanted to raise some thoughts/concerns because of an increased reliance on the internet and firefighters general laziness towards getting out there and truly educating themselves on the construction in their areas. We have found that by adding a quick and easy technique to the evolution, we can decrease the overall risk of the operation tremendously. So let’s get into it…

1)      Some older construction doesn’t use a ridge board. I do realize that there are older legacy systems that do not use a ridge board, for example “Bungalow Construction” which we find most commonly in “Craftsman” style homes whose prevalence in residential construction occurred generally from the 1900’s to the 1920’s. At least was the case out here on the west coast. The one major difference you have going for you in those structures versus todays structures was the use of 1”x 6” solid, red wood, sawn boards that were straight sheeted over and across the roofs “common rafters” versus the creation and use of Oriented Strand Board. When the roof ladders hooks are dug and hung on these boards we don’t generally have the same concern for those same hooks coming out or undone from the rafters as we do when these hooks are placed into nothing more than OSB. Oriented Strand Board decking rips and tears and is often the first portion of the lightweight roof to fail and come apart from the radiant heat of the fire. Also, we must keep in mind that because of the OSB’s flimsiness and shortened failure rate; minimum residential lightweight truss construction “on center” spacing intervals are 24 inches, and our ground ladders outside beam to outside beam widths are generally 19 inches; the possibility does exist for the ladder to fall through between trusses. We use Alco-Lite and Duo Safe ladders and this is their width. I’m sure that the majority of this is not news to you. This also speaks to a portion of your concerns in the next section.

 

2)      This brings me to your remarks regarding the use of Aerial devices in lieu of roof ladders. Being able to cut large enough holes from an aerial ladder is not difficult with some creative and aggressive training. In fact, the steeper the roof the easier it seems to cut from the aerial device. Depending on which way the pitch of the roof is facing, (front or Alpha side or traditionally running down the Bravo or Delta sides) you “throw” the aerial device to the front of the home or down one side of the home. In either instance, we just try to place the aerial a bit lower than where the sawman is going to be cutting, (keep in mind that we use chainsaws which seem to be quite a bit more maneuverable than rotary saws) 6 foot sawman, then lower the device approximately 7 to 8 feet (just an estimate and will vary based off of your crews height, experience, and skill level) to account for arm and saw length and to also keep the head of the sawman slightly lower than the  mid point of the h***. Based off of the conditions presenting from your cuts, do not automatically pull the boards or open the h*** until the aerial has been moved away and slightly below the h***. Keep track of wind direction. These are just some recommended issues/pointers to consider as there will always be obstacles, fire conditions, roof designs or other extenuating circumstances that will sometimes negate the ability to use the aerial. To get your crews competency level up for this operation will obviously take hours and hours of training and is not something that can be talked about at the dinner table or in this blog and then be expected to go seamlessly out on the fire ground. In my city, the bigger issue seems to be the trucks ability to “get the address” because of slower arrival times due to a disproportionate ratio of engine companies to truck companies. In this instance we go with ground ladders regardless of whether its lightweight or not. We just put some additional checks and balances in place. Diagnostics and kerfs are those checks and balances.

3)a. Cutting Inspection Holes. I do not generally perform inspection holes to identify construction type on a residential pitched roof unless something peculiar grabs my attention. I was advocating more for the performance of kerfs or diagnostic cuts to identify smoke/fire conditions directly below where we will be performing our vent operation. You ask where would I be placing these? I would make a quick kerf midway and then another triangular indicator cut high in the field where my cut will be. This takes seconds to accomplish (with a chainsaw). Fire conditions are a noteworthy concern when firemen are 100% reliant upon the roof system supporting the roof ladder and their weight long enough for them to affect ventilation. In my department, our Flat Lightweight roof operation calls for the adherence to the principle and mindset of “trading space for time”. Meaning that we obviously want to make our vent opening directly over the seat of fire but in the event that the fire has entered the truss space, we must trade up a minimal amount of roof to accomplish the ventilation operation without becoming part of the problem. This can end up being 2 feet of roof traded up or 10 feet of roof traded up.  An ongoing size-up on approach and the use of these quick diagnostic cuts can assist us in guessing the location of the fire and consequently the level of involvement directly underneath our position. The same rule applies to the steep pitched roof. We will trade up a little space for time to try to limit the risk of roof failure and our subsequent injury and or death.

3)b. Regarding construction identification through the use of inspection cuts. As I stated above, I do not typically perform these on pitched roofs. This is a technique that I perform on most flat roofs and have found an extreme amount of success in it. When these are performed we need to keep them just large enough for your “turned out” arm to fit into them. We don’t just look through them as this would prove futile with a moderate to heavy smoke condition. We insert our arm into this h*** and physically grab the system. This tells a whole lot to the firefighter who is knowledgeable and familiar with their building construction and how it behaves under fire. Let’s say for whatever reason I felt that an inspection cut was warranted to identify the construction of this steep pitched roof and I reach in and grab an engineered I-beam (TJI) or a cathedral truss top and bottom chord or a 2” x 10” rafter? Well I think you can see where this can be a useful tool that can undress the entire roof system and again only takes seconds to perform.

3)c. Roof covering & thickness.  I don’t usually care about the roofs thickness in the pitched setting. I listed all of those under the picture of the diagnostic cut just to demonstrate all of the general information you can glean from the performance of this cut. I don’t want to make something out of nothing but as firefighters and specifically roofmen we must be aware of all of the various coverings and green alternative roof systems (S.I.P.s etc.) that are available and becoming more and more prevalent. Again, I am not advocating that you take the time to find out what type and how thick the roof covering of the roof is but if something just doesn’t look or feel right then maybe a diagnostic cut is warranted. Here in Las Vegas, the ratio of cut and stack or older construction to Lightweight, pre-engineered construction is somewhere in the area of 15% conventional to 85% lightweight. And please keep in mind that this is the desert southwest where energy efficiency and protection against 125 degree summers is everything. However, you probably have the same issue up there against freezing winters.

4) "A system that takes the thinking out of it for us!"  -There is no such animal on the fireground.”

I couldn’t agree with you more!!!

 

 

Comment by David Rickert on September 27, 2013 at 1:29am

Colin I will attempt to address your concerns point by point.

1.Milwaukee method as it pertains to engineered construction or construction without a ridge board/pole 

2.Sounding of the roof

3.Cutting an inspection h*** in the roof

4.Opening up from aerials and other miscellaneous thoughts

1.Truss(pun intended) me I am fully aware of lightweight engineered roof systems.Milwaukee does have buildings built after 1980 and while they do not account for a majority of fires in the city they have and do occur in these types of structures.Many people may also not be aware that a good number of homes built in the early 1900's and before, may not have a ridge board/pole.It seems building codes were rather fluid during this time and it was left to the discretion of the builder as to whether or not they wanted to include one.I have used the Milwaukee Method on Just about every conceivable type of peaked roof construction and have had success with pretty much all of them.I would make one notable exception to this and advise against using this or any method for that matter on any large span engineered roofing system such as on a church or large Mcmansion style home.

  The adjustment you can make for those times you may not be comfortable with sliding the ridge is to place the second roof ladder when you are halfway up the first roof ladder, this ladder should be placed  ~ 4ft away where it can then be accessed from the safety of the first roof ladder.I have used this modification in several situations,one was in the case of a ridge vent that was forcefully venting fire and prevented me from sliding the ridge and several other times it allowed me to place a roof ladder on the other side of a chimney.Otherwise I usually slide the ridge even on engineered roofs which brings me to the next point-

2.Sounding the roof- If you are setting up on a suspected lightweight engineered truss roof,remain in contact with the second roof ladder while forcefully placing it onto the roof, all the while keeping it in front of you as you slide out onto the peak.This will give you every indication of roof stability that can be achieved by sounding with an axe or tool.Placement of the first roof ladder will also give you a pretty good idea of what condition the roof is in.Roof evaluation should be ongoing from the time you arrive to the time you leave the roof. I realize the video shows the placement of the roof ladder as more of a toss and scoot,which works just fine for most roofs,but if you are looking for that added security just perform ladder placement as detailed above.The video was shot to show the basics of the operation, there was no time for the variations,but maybe in the future I will be able to do that as well.

3.Cutting inspection Holes-I am not sure where you want to cut the inspection h*** but I see absolutely no value in doing this on a peaked roof.Will you be cutting down low? or up high? If the h*** is forcefully venting which i would expect when cutting above the fire then you will have a hard time seeing anything much less making a determination about exactly what kind of construction you are dealing with.You will already have a pretty good idea on the roof type based on visual cues and familiarity of building construction in your area. If you are trying to determine covering type and thickness I would ask why? It is not going to fundamentally change your operation you are still going to be cutting and opening the roof so taking the time to find this out by cutting an inspection h*** is a waste of time.If you really have to know just drive your axe into the roof this will give you all the info you need in regards to thickness, type and toughness.

4.Opening up from an aerial device would be my last choice.I have yet to see any proof that opening up from an aerial device provides anything but a small h*** that takes too long and puts the operator in awkward positions while cutting the roof.

 "A system that takes the thinking out of it for us!"  -There is no such animal on the fireground.Applying any tactic no matter how systematic or well honed requires that we constantly evaluate how where and when it can best be applied in regards to fire conditions ,building construction and crew capability.I would hope to amend this statement to " A system that yields the best results in both efficiency and safety as applied to peaked roof ventilation"

I will stop there as I do not want to exceed the length of the original blog. I hope this clarifies some things in regards to different types of roof construction.I look forward to further discussion.

Comment by Colin Kelley on September 23, 2013 at 5:13pm

Well timing is definitely everything! My mother and step father, who live in South Dakota, are helping with the construction of an additional room at there neighbors house and sent me some pictures of the truss constructed roof secondary to this blog. They were able to answer my question and quench my curiosity regarding the hanging of these trusses without the use of a ridge board. Here ya go. This should raise even more concern, as Chief Havel pointed out, especially for all you mid-westerners, on the reliance and expectation of any type of ridge support. The building is
 your enemy. Know your enemy.

Comment by Colin Kelley on September 18, 2013 at 8:34pm

Chief Havel, your added insight is much appreciated. A working knowledge of building construction is in my opinion and likely yours, the foundation to intelligently aggressive and effective fire ground operations. One must stay constantly vigilant and observant to this ever changing, ever evolving industry. It is an interesting observation of mine that what might be the normative design or technique for truss construction and shear resistance in one region can be the complete opposite in another. Legislation and varying ordinances have a monumental influence on this. For example, you cite the installation of ridge blocking(stiffeners) in your region as rarely utilized and according to the installation documents that as you pointed out are delivered with every new load of trusses, ridge blocking is not clearly recommended or mandated. In my region, especially in my city, the installation of this ridge blocking is most definitely the norm and when we speak with the structural truss design engineers, they clearly state that they would most assuredly never allow this feature to be left out of their truss design specifications. It is an integral feature that gives the oriented strand board decking a place for edge nailing to allow the diaphragm shear resistance to transfer up and over from one slope to the other. In countless post fire inspections,in service and off duty pre-plans, I can honestly say that I have never witnessed a pre-engineered, residential, truss constructed roof absent of this feature. However, there's a first time for everything! I am a constant student of this career and I am always attempting to increase my awareness and knowledge of the building construction that we do battle in and on top of. With respect, thank you again for taking the time to add to the value of this post! Your interrogatory has truly increased my knowledge and made me a better firefighter! 

Comment by Gregory Havel on September 17, 2013 at 7:45pm

Mr. Kelley--

In the middle of the second paragraph, you mention a "stiffener" or "filler stud" that is toe-nailed between the peaks of roof trusses. Unfortunately, most roof truss assemblies do not include these, and the ridge area may be even less stable than we might assume. Truss roof assemblies today depend upon permanent bracing between truss members and the plywood or OSB sheathing on the roof for rigidity and stability.

This link is to the 2013 edition of the truss installation and bracing handbook that is included with each shipment of trusses from many manufacturers: http://www.sbcindustry.com/docs/06_BCSI_booklet_FINAL.pdf  In addition to showing the proper way to install temporary and permanent bracing on wood trusses, it also shows photos and diagrams of ways in which trusses should never be handled or installed. (Unfortunately, these methods are often those that are used.)

To your well-written blog, we should perhaps add a caution that when cutting ventilation openings, we should not cut through the top chords of trusses, nor should we cut through any of the bracing between trusses that might be in the area. Either of these unintentional cuts could make the truss roof assembly less stable, and lead to its early collapse.

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