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Heavy Timber Wood-Truss Roof

Wed, 24 Mar 2010|

Paul Dansbach examines firefighting problems at a structure in which a makeshift storage space has been built on the truss loft.



Hi -- -- dance back and welcome to fire engineering training minutes. In this session trading minutes we're gonna take a look at an ordinary constructed building that as a heavy timber would truss roof. We're going to talk about some of the -- problems -- trusses. One of the biggest -- problems -- trusses is that there is worse or -- mass ratio. Another far problem particular to this building and many other buildings are out there is the fact that the trust -- has been converted -- storage space. As we look at these trusses were going to see what was at one point a wide open space. Has been converted to a storage area. A stairway has been installed if ward system has been stole our forces that -- supported by the bottom word of the heavy timber would trusses. The heavy timber would trusses were never designed to support. The load of -- war and the materials. That harsh -- word often that storage space within the trust well. Let's review some far problems created by a trust of this nature. First the -- access to the storage space access to the storage space in this polling is -- this stairway. Missed fairways very limited in size and very state. Advancing -- -- line up that's their way will be challenging. Another fire problem created by the truss construction. Is the large volume of space. Up to the ceiling -- the other side of the roof deck. If there's a fire in this building. That's base is going to allow the heat to humility. Before the true condition is felt at world level. Often disguising. The true fire conditions to fire fighters operating at war while they may not understand. The volume wire that exists above their head. When this -- was -- largely constructed. There were no obstructions the on the side of -- that firefighters could easily apply a hose stream from the floor up into the trust based. And extinguish any fire that was up in the trust space were burning on the other side of the roof -- As a result of the alteration and the addition of the storage walked to the trusses. Firefighters no longer have the ability to apply a hose stream for the burning material of the burning structure located above this war -- That's another limitation. And another hazard that this alteration has presented to the far -- This is a hazard that's very common. In buildings of bolstering. Truss roof construction. -- looking at the exterior walled building. We're going to look at where at the point where the roof slopes down to the exterior -- What we're looking at is -- and deterioration. Of the roof decking. That rock and deterioration. Are the result of years of water leaking through the roof and deteriorating. -- would. Roof structure. This is an area where firefighters walking across the roof. There are likely default rule the deteriorated roof decking and into the building. As the result of the additional weight imposed on the bottom word of the trusses. The owners of the building have attempted to support the trusses in another -- Here we see it's PO column has been -- -- all along to support the bottom -- of the trust additionally. -- you channel has been bolted from the bottom word. Of the would trust in an attempt. To make the trust more stable and able to support the additional -- imposed on the bottom cord. By the -- decking and trust -- Okay were up in the trust loft area again up in the space that has been created by the installation of -- floor on the bottom quarter of the trusses. Let's take a look here we've seen the popcorn of the trust's. We see the web members of the trusses and we see how the web members are attached to the bottom ward for the use of threaded -- As you walk through this trust -- space. We're gonna notice that the building has been deteriorated as a result of the age of the structure and the loading of the trust -- As we look around we see Iraq this raptor had split. As a result of movement of the structure of -- of the structure deterioration of the structure. We continue to move around. We're going to look acting next trust over at the top word of one of the trust as we can see that there are three web members. That are damaged. Where -- attached to the top word of the trucks. All three of the web members -- split. And hold from the top word as a result of the won't imposed upon the bottom quarter of the trials. The weight impose on the bottom quarter of the trust's. Is attempting to poll the two -- the top and bottom awkward part for me drawer. Notice the cracking and splitting of the longer. As we look at these web members. Another indication of the amount of damage is how far. The web members have been pulled from the top court. And this is indicated by the paint line on the web member that you're currently doing. Understanding trust construction is of Paramount importance to -- firefighters. Firefighters -- identify all the buildings in their jurisdiction. That have some form of cross construction. Additionally. Visits to these structures will help firefighters understand the firefighting challenges and problems posed by these buildings. Thanks for watching the section a fire -- hearings trading minutes.

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