c-

To an extent the brick directly above the opening forms a flat arch, 
whereas the brick higher up does form an arch. The mechanic tends to 
feel this arch is happening even if they don't quite understand it. So 
it is not exactly free hanging brick. Friction, ties and back up mortar 
(which in theory in many constructions should not even be there but is 
more a result of slop if it is there - impedes water from getting out of 
the wall) does help to hold a brick or so from moving, particularly if 
the brick removal process vibrated the crap out of the masonry and 
loosened up the brick to remain in place... as in caused cracks in the 
mortar joints. It is possible to remove these brick above the lintels 
and never need to prop the remaining brick up - but you need to know 
what you are doing. Though we don't want that kind of a revolt movement 
amoungst our in-field mechanics. Problem is in efficiency of demolition, 
as opposed to a wholistic approach to maintain the integrity of the 
surrounding masonry, usually the crap gets beat out of the masonry, 
particularly w/ the insensitivity of electric chipping guns, and it is 
good sense to put in a few props. Most mechanics sent out to do the 
brick removal and lintel replacement don't have a clue what they are 
doing so it is best that they be trained to put in props. So it is 
really up to the mechanic to sense what is going on and if needed to 
prop real quickly, like in immediate action, or if they are more atuned 
to doing neat work that does not fall down to prop at the end of the 
day. To prop or not to prop is not regulated.

Lintel replacement in brickwork is a commodity in NYC and therefore 
keeps pushing to the lowest-cost-denominator and the most used place to 
cut cost is in the intelligence of the mechanics applied to the work. 
The market and industry has it pretty much down to the dollar what is 
involved to replace a steel window lintel by the LF cost.

][<en

[log in to unmask] wrote:

> Lintel repairs all around me... After the three or four rows of brick 
> are removed to get at the rusting lintel, I notice that 2x4 stock is 
> used to prop up the now free-hanging brick above the repair void. 
>  
> At what point, if left unsupported, will these bricks fall?  I assume 
> they are held in place only by friction, ties and back up mortar.   I 
> mean, do you have to brace them every brick or two, or can you just do 
> it at the end of the day.
>  
> c
>  
> PS did you see that documentary on the tunnels of The Great Escape, a 
> couple of years ago?  They found the German POW camp, excavated the 
> tunnels, found the rails, the wires, everything.  
> -- To terminate puerile preservation prattling among pals and the 
> uncoffee-ed, or to change your settings, go to: 
> http://listserv.icors.org/archives/bullamanka-pinheads.html 

--
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