Point 6 of my 12 point list of methods for reducing cracking in portland cement stucco



                     Point six- Don't pile heavy materials
                  against the wall, and no excessive beating 
                  and banging

 This is largely out of control of the plasterer, but it should be insisted on.
 There is nothing worse than seeing a big stack of sheet rock stacked against
the wall, where the the stucco was recently finished on the other side.
If a sheet rock delivery is made, it can stacked against a partition wall, that
doesn't affect the stucco. You can't tell me that a stack of sheet rock that
weighs 3000+ lb. leaning against the wall won't bow the studs enough
to seriously crack the stucco. Since there is no guarantee against cracks,
I reserve the right to say nyah nyah nyah, however one person's action
changes the quality of the product for everyone. So I must insist and insist.

 The outer walls on the inside are usually the most inviting places for material deliveries, such as paneling, plywood, etc.

 Once we had a stucco wall that cracked severely a few months after we
finished when a contractor bolted a heavy bay window assembly to the wall,
which should have been installed before the stucco.
 I took some prospective customers by to show the house as an example of
our work, and to show the great impregnated color. I had been by a few 
weeks earlier and there wasn't even a small hairline crack, making it a great
example( put your best foot forward, right?) I could see the disappointment in their faces when they saw the big nasty cracks radiating out from the bay window.
 I was embarrassed.
 When they called me to tell me they had decided to put on a different material
on their house, I knew the real reason.

 Electrical openings, plumbing rough outs, exhaust ducts, etc. should always
be made before the lath is applied. I have seen neglected pipe openings knocked
in later with a sledge hammer. In this event, the holes should be carefully made
with a diamond or carbide blade.

  Windows and doors should be checked before the lath is applied also,
for alignment, proper opening, etc. Prying a window jamb or beating
it out will crack the stucco every time.

  All I can can do on all these cases is insist that these things be observed,
but none are my fault.

On masonry:
Patches and blocks extending walls should always be toothed in,
and not just butted tight. There will always be a nasty crack if blocks aren't
toothed in.
Blocks extended on this multi-million dollar are loose enough to shake. I took a picture to show that when a nasty crack appears, it was due to an inadequate substrate.

  Last but not least, is  to insist that heavy roofs, such as slate or Spanish barrel tile,
be put on before the lath is applied. Several tons of roofing will bow the framing
and crack the stucco. The disadvantage of doing this is that chimneys and dormers should stuccoed first, to avoid walking on the roof and breaking it up.
 When I was in Southern California, I noticed a lot of times, the barrel tiles were loaded on the roof before they were installed. This allowed the stucco to proceed 
without loading the roof later and cracking the stucco.