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Re: Firewall construction

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I was trying to write the same note while I was at work but my office
server was down.  I agree with Harold that in your case (I forget if you
were the originator of this thread?) I would use two walls. I have only
used cantilever walls with short single storey firewalls. I have used the
weak link tied method with wood framed roofs. Otherwise it usually ends up
being the double walls. I usually use them as bearing/shear walls as well
if I can. The other types of tied walls seem to work with simpler, more
symmetrical buildings only. 

I have had the same problem with locating doors. I ended up building a
cantilevered section for a two storey building that had a concrete column
on each side of the door frame and a deep concrete wall/beam supporting the
floor. I have not connected the floor to this structure but have limited
its movement with how the floor slab was detailed. This seemed to address
the concern of one wall containing the door collapsing and causing a
breech. It was the only thing that I could come up with..and as usual I
could not find anything about this in any reference on firewalls. The easy
questions are always covered well though. 

I am sure that the building officials that I am dealing with would not
question whatever was done on our drawings because I have yet to meet one
that understands the requirements. They would not blink if you built a two
storey, minimally reinforced 8" block wall that was sandwiched between wood
framed structures with no ties. I just felt that in order to do it properly
we would have to address the large opening in the wall that would be left
when one of the walls prematurely collapsed due to fire on the "wrong"
side. Does anybody have any thoughts on how to get around this problem?
David Handy, P.Eng.
The Thompson Rosemount Group
Cornwall, Ontario, Canada
Views expressed are a personal opinion only. 

> Harold,
> Most firewalls I have encountered have doors in them. How does that work
> with the double wall method? Are there two sets of doors right up
> against each other? I have a hard time visualizing how this works.  
> Thanks,
> Rick Burch