Thread: Thin stucco coat?

Came across a home that had visible outlines of all masonry blocks and mortar junctions. Is this shoddy stucco work, too thin of a finish coat?...Any implications for this?

Sidney Alstad

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It's probably a one coat "cementitious" coating, similar to drywall texture. Not really stucco, and its applied too thin to cover the substrate.

appears they missed a few important details
maybe the lath and base coat for starters

Parging...maybe 3/8"

Originally Posted by BARRY ADAIR

appears they missed a few important details
maybe the lath and base coat for starters

Unusual system there, lath on masonry ... lath is not required on masonry, although I have seen a few installation specified and installed that way.

From what I have seen, the lath on masonry just makes the system more prone to failure because of the lath and the attachment of the lath.

Originally Posted by sidney alstad

Came across a home that had visible outlines of all masonry blocks and mortar junctions. Is this shoddy stucco work, too thin of a finish coat?...Any implications for this?

Sidney Alstad

This is probably a cementitious material genericly referred to as surface bonding agent. It uses fiberglass strands to bond together and can be used in leiu of mortar between the blocks. Durabond and surewall are two brands out there. The block is dry stacked and the surface is parged with this material.

Ashley Eldridge
CSIA Director of Education
Chimney Safety Institute of America (CSIA) | Plainfield, IN

Originally Posted by Jerry Peck

Unusual system there, lath on masonry ... lath is not required on masonry, although I have seen a few installation specified and installed that way.

From what I have seen, the lath on masonry just makes the system more prone to failure because of the lath and the attachment of the lath.

understood
though it is one of the accepted applications
when the lath is installed correctly the telegraphing mortar joint issues associated with stucco on cmu usually becomes a non-issue

it may boil down to expectations
the consuming population expect installers to do it right the first time and discontinue the production of disappointing disposable properties

until that time we'll continue to be employed and see what is in the op pix and worse

Originally Posted by Stephen G

Parging...maybe 3/8"

I agree, just a Parging job. From what you are showing (I an seeing) I would not say that it is a bad job. You may not like the look, but that is not the issue,is it?

You need to think back as to why it was Parged in the first place.

Is the pictures on a rear/side basement wall?

Originally Posted by sidney alstad

Came across a home that had visible outlines of all masonry blocks and mortar junctions. Is this shoddy stucco work, too thin of a finish coat?...Any implications for this?

Sidney Alstad

That is what I call a smear coat... (same as a parge coat) They use a stucco finish coat and "smear" it on the block. I see it most commonly on brick. I did a high end home a few weeks ago that from the street the home looked like stucco but as you go to within 20' of the home you could see the individual bricks.

What is in the picture looks like crap. I would take a few pictures and simple say the the finish coat on the CMU needs to be refinished if they want it to look better. It is not going to hurt anything it just needs a new coat, but I would also let the client know that they will always see the individual blocks.

Originally Posted by BARRY ADAIR

though it is one of the accepted applications
when the lath is installed correctly the telegraphing mortar joint issues associated with stucco on cmu usually becomes a non-issue

1/2" or 5/8" thick stucco on masonry also solves that problem.

Common in our area – as mentioned parging coating. I never heard of it until I moving here. Suppose to help damp proofing but I’ve never understood how as it’s a (vapor permeable) cementitious product too. Personally I think it’s more for cosmetics than anything. However we’re suppose to point out any defects (cracking, flaking, etc,) in it so I do.

My guess would be it's efflorecesne; salts released from mortar jonts.
Or possibly caused by the motar joints have higher suction than the block causing a different color when drying. Tuff to tell for sure by the picture but it looks like a very light spray finish, on block mortar joints struck flush, on you get a different draw from the substrate .

Sidney,
Based on the photos, looks like a thin parge coat, perhaps EIFS base coat and maybe acrylic finish, with moisture problems. Some effloresence visible on the block as well as at the joints. Stop water intrusion at top and/or back side of wall- clean off effloresence, let dry completely, including water in block and paint.
Lath is not necessary over masonry, but can work if properly installed- still won't keep water from coming through the top or back of the wall.
If dry stacked and skimmed with fiber reinforced stucco (Surewall, etc), you still need to keep the water out.

Mike Minigh
MoistureTech
304-904-6055

Ironically, I saw this post immediately after registering onto this site. I was a metal lather for 30 years as was my dad. His father was a plasterer. I've seen many cmu walls plastered with and without lath. In my opinion the added lath helps prevent cracking and creates a better product because there HAS to be a thicker coat of plaster if only because there should be a scratch, brown and then finish. Typically 1/2" on block is acceptable in 2 coats. In this case even 1/4" would have been better. I see the efflorescence too. In any case it's a cosmetic issue not structural.