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Fire Damaged Brick Chimneys

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When I investigate fire damaged brick, there are two things that I look for:

The first is if the mortar was damaged by the fire, i.e., did the mortar sand 
get hot enough to expand and destroy the integrity of the mortar.  I imagine 
that there are more sophisticated methods of checking this, but for a first 
check, I rake the mortar joints with a screwdriver.  Good solid mortar will 
just show a mark, but fire damaged (and old lime mortar) will just rake out.

The second thing I check is to see if the brick had been damaged.  
Considering how brick is made (and fired) it should take quite a bit of heat 
to damage it.  Really fire damaged brick will have the surface spalled off, 
so I tap the apparent undamaged brick with a hammer.  Undamaged brick will 
emit a ringing sound; brick which has delaminated and is ready to spall will 
emit a dull sound.  You can't avoid noticing the difference.

As far as cleaning soot, if I determined that the brick masonry was sound, I 
would leave the cleaning methods up to a damage restoration company.  They do 
cleanup all the time and I would hate to specify what they should do.

Hope this helps.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Michael Krakower wrote:

. > An engineering friend of mine is evaluating several surviving brick
. > chimneys for an insurance company after the surrounding wood frame
. > residences have been gutted by fire. Is there a written methodology by
. > Factory Mutual or other similar sources that he might use for the
. > evaluation? Topics of interest include structural integrity, cleaning of
. > soot, field testing etc.

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