Wood Mansard roof 1

[TravisMack]

I have a retail building that is constructed of metal deck, steel beams and joists. The building below the roof deck is protected with a wet pipe fire sprinkler system designed to OH2. On top of this roof, all along the perimeter, is a 10' tall X10' at the base triangular roof mansard constructed of wood trusses. There is nothing in this space. It is for an architectural feature only. There is no access to this space. I realize this is a concealed combustible space, but does it need to be protected with sprinklers? There is no mechanical, electrical or plumbing equipment in the space. The only thing that will be inside of the space are the wood trusses and the sprinkler piping.

Is there anything in the standards that would allow this space not to be sprinklered? I am going on the basis of all spaces to be protected and there is nothing that allows this space to be omitted, but it really doesn't make sense to have sprinklers in there either.

Thanks!!!

 

[stookeyfpe]

Travis

Is the mansard separated from the remainder of the building by a fire resistive wall assembly? If not, I would probably require sprinklers unless you can get the mansard separated using draft stopping.

I think you have a solid case for an alternative means and method (AMM), which is allowed by the IFC. Based on your original posting I don't see any benefit in adding sprinklers in this area.

My question is what will keep the tenants or owner out of this space? I've seen mansards used for illuminating of walkways. I've responded to two greater alarm fires in my career that started when the electric sign on the mansard had an electrical short and the fire started running horizontally in the mansard. My first incident we literally went 30 feet past the fire, cut out a 4-foot section of the mansard, and then commenced the attic. Mansard fires are ugly events because if your a firefighter, at some time during the incident you will need to get under this structure, and its got enough dead load to make for a bad day if it collapses.

 

[TravisMack]

Stookey:

As always, thanks for the input. I like the engineering aspect coupled with real field fire fighting. The project is located in the midwest and the project engineer has already specified sprinklers in the area. As I was drawing the system, I got to thinking that it may not be that great of an idea to have it. However, I am sure there will be electrical signs and stuff from the mansard. The sprinklers may be able to help control and incident until the arriving FFs get there.

I will just go with the specs on this one and keep on drawing the system.

Thanks again!