After a year I have the following problem, pieces of plaster (1+ inch
deep, 4"x5" on the surface) from vertical walls occasionally (every 4-5
months) fall off. The problem according to a contractor is the cement.
I think that's without doubt as the plaster falls of with a small piece
of cement always ( about 1/8" ) .

The reason for this was attributed to bad cement mix: The original
fault I was told was the addition of too much water to the mix. does
that sound plausible? provable? The gravel seems to be also a bit too
oblong, slits rather than rounded, but of medium/fine size.

The remedy is quite expensive, injections into the cement. But only
local treatment. Given the rather rare occurrences, and since I repaint
every 2 years maximum, does it really worth it? ( total house surface
1600sqf)

Other solutions
- total replastering ? ( with global cement treatment)
- glass fiber cloth ? ( on existing plaster, without cement
treatment)
- covering with prefabricated plaster on metallic trellis base, on
top of existing regular plaster.

Your ideas?

I could also pursue legal remedies but... am not sure what is best.
it's a bit of gutting experience.

wrote in message
oups.com...
After a year I have the following problem, pieces of plaster (1+ inch
deep, 4"x5" on the surface) from vertical walls occasionally (every 4-5
months) fall off. The problem according to a contractor is the cement.
I think that's without doubt as the plaster falls of with a small piece
of cement always ( about 1/8" ) .

The reason for this was attributed to bad cement mix: The original
fault I was told was the addition of too much water to the mix. does
that sound plausible? provable? The gravel seems to be also a bit too
oblong, slits rather than rounded, but of medium/fine size.

The remedy is quite expensive, injections into the cement. But only
local treatment. Given the rather rare occurrences, and since I repaint
every 2 years maximum, does it really worth it? ( total house surface
1600sqf)

Other solutions
- total replastering ? ( with global cement treatment)
- glass fiber cloth ? ( on existing plaster, without cement
treatment)
- covering with prefabricated plaster on metallic trellis base, on
top of existing regular plaster.

Your ideas?

I could also pursue legal remedies but... am not sure what is best.
it's a bit of gutting experience.


Cement and plaster are two completely different applications.
Stucco does have cement in it. Stucco can chip and peal if improperly
installed. If you bought the home new use your warranty.

Plaster is typically used inside on very high end homes.

Your statements for me are confusing and hard to understand.

SQLit wrote:
wrote in message
oups.com...
After a year I have the following problem, pieces of plaster (1+ inch
deep, 4"x5" on the surface) from vertical walls occasionally (every 4-5
months) fall off. The problem according to a contractor is the cement.
I think that's without doubt as the plaster falls of with a small piece
of cement always ( about 1/8" ) .

The reason for this was attributed to bad cement mix: The original
fault I was told was the addition of too much water to the mix. does
that sound plausible? provable? The gravel seems to be also a bit too
oblong, slits rather than rounded, but of medium/fine size.

The remedy is quite expensive, injections into the cement. But only
local treatment. Given the rather rare occurrences, and since I repaint
every 2 years maximum, does it really worth it? ( total house surface
1600sqf)

Other solutions
- total replastering ? ( with global cement treatment)
- glass fiber cloth ? ( on existing plaster, without cement
treatment)
- covering with prefabricated plaster on metallic trellis base, on
top of existing regular plaster.

Your ideas?

I could also pursue legal remedies but... am not sure what is best.
it's a bit of gutting experience.


Cement and plaster are two completely different applications.
Stucco does have cement in it. Stucco can chip and peal if improperly
installed. If you bought the home new use your warranty.

Plaster is typically used inside on very high end homes.

Your statements for me are confusing and hard to understand.

As I say it's an 12 year old house, and I have it for a year now.
no warranty I belive, still looking into it.

As for the problem I have, it appears on the load bearing walls only,
these walls are made of reinforced concrete (with gravel & cement ok,
my mistake).

The walls are plastered on top of the concrete, it's an above average
but not really high end home.

So a chunk of plaster falls off, with a small piece of the concrete
attached.
As if some stresses in the concrete act to expell the surface part of
concreet.
Is it clearer now? not a common problem right?

Still not totally clear - Are we talking about inside or outside?

Definitely no recourse (Legal, warranty or anything) You fix it its
yours.

I do not know what "prefab plaster" or "metallic trellis base" is
either.

Some of what you describe makes us think exterior, that's why SQLit
mentions stucco, an exterior masonry product. Some of what you describe
makes me think interior (plaster is used for interior wall finishes and
is more or less common depending on where you live)

Water infiltration could be the cause of what you describe, regardless
of interior or exterior.

Lets spend a bit of time on terms and better description of the problem
so we can all be on the same page.

Stucco - Exterior masonry finish, generally has some texture, applied
in layers. Usually has a wire lath for attachment.
Lath - First step for stucco or some plaster finish techniques
Wire lath - lath made of wire common with stucco, very unusual for
interior plaster jobs except for maybe some south west adobe looking
projects.
Wood lath - lath made of wood, common on really old houses.
Blue board - common underlayment for modern 'veneer plaster'
applications.
Veneer plaster - plaster applied over a gypsum board, similar to
drywall, commonly called blue board.
Plaster - basically gypsum and water - does not shrink. Used to make
some moldings as well as wall finishes. Interior use only.
Parge - This term may be regional. A masonry mortar skim coat over,
usually, a block wall to give a smooth finish. Sort of similar to
stucco but not textured and probably a higher Portland cement content,
not lath is used.

OK, now can you use these terms, as appropriate, to describe your
problem. Please tell us if its outside or inside, high on the wall or
low. Near a window or any other commonality. Load bearing wall is
interesting observation but may or may not be relevant. We'll see.

Pictures may be useful too.

ok right, indeed it's interior, and has happend already at different
walls, various positions on wall, including on totaly indoor wall (no
exterior side). No water infiltration
I can rule this out for sure. Always only on load bearing concrete
wall. The exterior is brick so no problem apparently there. The
problem appered on ground level and 1st floor.

The plaster it's usual gypsum, about 6/16" thick, for interior,
smooth mat finish. I used it already to successfully repair a few
holes.

as for the options I proposed as remedy,

-the prefab plaster is the gypsum blue boards, on a metalic base
safely attached on existing walls, without removing the existing
plater.

- total replastering plus concrete treatment ( most expensive? )

- some durable glass fiber wallpaper (not the most aesthetic for
sure)

or wait and repair/repaint as the problem appears, this is the cheapest
but most taxing solution on our nerves. 1 wall per semester...if lucky

Prefab Plaster- How are you going to safely attach to defective
concrete?

Total replaster- You're still going to be attaching to defective
concrete (what type of concrete treatment)

Durable glass- The the plaster/concrete will still come off, only
slower and less noticable. You'll eventually see bulges in wall

Wait and repair-repairs are still going to be on defective
concrete-repairs will eventually come off- could be a year, could be
20.

Causes-sand/cement ratio, too much water, contaminated sand (ie: beach
sand), frozen concrete,

Permanent and definite fix- Stud up on both sides and and replaster


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Permanent and definite fix- Stud up on both sides and and replaster

I'm not sure I see what you mean by "Stud-up on both sides".


How are you going to safely attach to defective concrete

I tend to think this is the best solution, the house withstood 10
years +
and I have hung on walls heavy objects with no problem, so i think
masonery screws should be secure for the blue boards base.

the contractor suggested doing "carrot" test for the concrete. would
that be useful?

thanks