Don Y wrote:
[apologies, this thread slipped out of my display "window" -- out of
sight...]
On 10/3/2015 2:45 AM, dadiOH wrote:
Don Y wrote:
~1980 house is built of stucco over cinder block (in some places)
and slump block (in others).
There are long, narrow, noticeable cracks in the exterior stucco
suggesting some subsidence (water is all ground sourced, here).
Neighbors suggest "just slather some paint over it". frown
Is it OK to just patch these cracks? Or, should we expose the
underlying blocks to get an idea as to how much they've penetrated
the structural block?
If *just* superficial, any advantage to polymeric patches vs.
(cement) "stucco patch"?
And, if the cracks permeate the underlying block (presumably on
mortar lines), what's the recommended remedy? Anything
"injectable"? (fine mortar, cement adhesive, etc.)
Since the cracks are there because of movement, I would not use a
cementatious material to patch them.
Why? What do you see as the downside? If the building is still
"settling", wouldn't any new mortar lines open themselves under the
continued strain?
**********************
That's why I don't use cementatious material...it cracks. Caulk stretches
to a point; if it later stretches to the point of breaking, THEN I would
worry about WHY things were moving and - possibly - comsider methods of
prevernting it.
Concrete/mortar just doesn't like any movement. My house is block on slab.
The slab did its cracking long ago, settled down after it did. I don't
recall any stucco cracks on the house walls save one lanai that has two end
walls that are stucco over ply over studs; there were a few hairline cracks
early on, caulked almost 20 years ago, still good.
There is a knee wall around a courtyard; it developed some cracks following
joint lines, a playing card size piece of stucco sloughed off too. All were
repaired with polyurethane caulk maybe five years afo, all are good.
A hose bib in the courtyard on a house wall started leaking inside the wall
maybe 8-10 years ago. After cutting out the stucco and block around it, the
problem turned out to be a nipple that had rusted out at the threads. After
replacing the nipple, the cavity was filled with foam up to about 1/4" from
the outside wall. I the used thinset to stucco the remaining 1/4". Still
good.
I have a seven foot high wall around a garden off the master bedroom. I
didn't have it stuccoed when I built the house, got tired of looking at the
joints so I used thinset to stucco the 30' of wall. I notice it has
developed cracks on the block joints in an area about 2' x 3' and will push
some caulk into the cracks someday soon.
**********************
I.e., how would such a repair differ from the way it *was*? Or, the
way the rest of the joints that *haven't slipped?
I don't understand what you are asking.
**********************
I want something that allows for a bit
of movement. I caulk and paint them.
So, you only deal with the cosmetic aspect of the stucco (surface)
and don't sweat any structural consequences?
**********************
For the cracks I am talking about - hairline to maybe 1/8" - I can't foresee
any structural consequences.
**********************
For hairline up to maybe 1/8 I use
acrylic caulk, I had a joint between a free standing wall and the
house that had opened up to 1/4 - 1/2, used polyurethane caulk.
We have a similar issue with a wall that adjoins the house and
supports the back/side gate. The closing of the gate inevitably causes
the
wall to "move" wrt the house, opening a large crack. I plan on
sinking some bolts into the house and tying the wall to them. Then, fill
with
mortar.
**********************
I think that would be a mistake unless the footer and block for the wall
were tied into those for the house when built. If not, and if you tie them
together, movement in one will affect the other. If they are separate, the
norm is a "cold" joint...one that allows for independent movement.
**********************
The norm IME for stucco cracks is on block joint lines, easily
visible. I
Yes. Very apparent (for masonry homes). Stucco on wood frame seems
to generate arbitrary cracks -- typically more vertical than running
along horizontal mortar lines as with block.
IME, the cracks are as likely to go on vertical block joints as horizontal;
usually, both.
haven't worried about whether the cracks penetrate into the block
joints as there is nothing I could do to repair same without major
effort and expense and I view some joint cracks rather the same way
as I would in wood; i.e., minor local damage does not impair the
whole.
I was considering opening the stucco and seeing if there was a
substance that could be "squirted" into any cracks in the mortar lines.
Then,
repairing the stucco (house is due to be painted, hence the reason
for addressing it now)
**********************
Well, I guess you could run some epoxy in but what good would it do? If
there is movement again either it would fail or new cracks would open up
elsewhere.
Keep in mind that block walls are very strong in compression but quite weak
in shear; very easy to push down a block wall. Also, a tiny, almost
imperceptible bit of movement can open a crack farther away that is many
times the size of the movement. Rather like a lever and a fulcrum...move
the long part of the fulcrum and that movement is amplified at the short
end.
I'm not saying that cracks are a good thing, just that they are pretty much
inevitable, depending on the geology of the area. My house is sitting on
sand, 60' to rock. Stuff moves here - especially newly built stuff - and I
don't consider a few stucco cracks to be a structural worry. YMMV
