Hello all, I’m new to Breaktime…My question concerns portland based stucco. I am having a house built, and the stucco scratch coat was just applied about a week ago. The temps here have been pretty cold and I’m beginning to wonder if the stucco didn’t freeze. If I pick off a clump of the material, I can crush it to a powder easily. The contractor used a portland based product with fibers in it. Any help would be appreciated…How can I tell if this stucco job will be any good?
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The first thing I'd do is talk to the stucco sub.
Also, take a sinker and try to scratch the stucco where you think it froze and see how hard it is.
I'll be meeting with him this weekend. I understand the scratch coat is softer than the brown coat, but I didn't think it should crumble to powder so easily. I'll try your scratch test tomorrow...
That sinker isn't lead, it's a nail.
Joe H
Gotcha...
Thanks, Joe.I guess that test could have been inconclusive . . . <G>
If I scratch the stucco with the nail, what should I see? Should it scratch easily?
No. It should be hard like concrete. It is concrete, without the gravel basically.
Joe H
It will scratch, but it won't be gouged.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I met with the stucco sub today. He says this is normal. He is waiting to "water cure" the stucco. He says he will spray the entire surface with water and let that cure, then repeat the process again. This will harden the stucco to a concrete hardness. The product he is using is called Western 1-Kote. Any comments? I haven't seen this before, as my usaual stucco jobs have just been Portland/sand/lime mixtures...Thanks..
Western 1-Kote is a specially formulated fiber-reinforced material that is designed to take the place of the traditional scratch and brown coats.It is somewhat softer than traditional PC scratch/brown, and quite a bit more flexible.Consequently it has a little less impact resistance and much more resistance to cracking.I am a big fan of the material, properly applied it gives great results.It is normal for the chunks that are laying on the ground (the stuff that spilled) to be crumbly, I wouldn't worry about that. The stuff on the wall should be good and hard, though.Your stucco sub is being conscientious by coming back and spraying the wall twice. He is right, the additional water will cause the stucco to cure stronger.There's no way I can say from here if your stucco froze or not. If it did, it's junk. It will start falling off the house in chunks or sheets, usually.If it looks good, it probably is good. If it isn't, you'll find out soon enough and your sub should stand behind his work.
I appreciate your info on this product. I feel a little better about it. The question I have concerns the water curing process. Can you really apply this product as a base, leave it in place for 2-3 weeks, and then come back and water cure it after all that time? The sub says he does it all the time...
Ater the first 24 to 48 hours he's just wasting water.
Portland cement, sand and lime is the basic mix, it's mostly cured by then.
Joe H
"Ater the first 24 to 48 hours he's just wasting water. Portland cement, sand and lime is the basic mix, it's mostly cured by then. "
But then, you are one of those guys that garuntees his concrete to crack, aren't you?
Stucco is the same as any other portland cement product, it takes 28 days in the presence of sufficient moisture to reah it's design strength.
Design Strength is only about 90% of final strength. After 100 YEARS in the presense of moisture it will have reached about 99.999% of its final strength. There is some debate over whether or not the Colliseum has completely finished hydrating and it's had 2000 years to do so.
California require all stucco coated civlil defense buildings, like schools, hospitals and civic centers to have a 28 day moist cure between scratch, brown, and color coats. 2+ months from start to color coat.
SamT
Sam, maybe one of us is missing something, but if he's waited a week or more before starting to water it's kinda late. Should have been kept damp for the first few days.
Joe H
Also true.It's good to mist stucco for three days following application.If things have gone poorly for some reason, a little extra water won't hurt.Per my previous post, I've had concrete that I thought was garbage come around with continuous misting.
Joe,
"it's kinda late"
Well, that's a big "Maybe."
Was the weather really humid?Did it rain?Storm?If it froze, was the weather really dry?Any seismological events?Any strong winds?Any impacts?Etc?
This 'crete was applied as a stucco scratch coat, which has a rather different configuration than usual for concrete. More like tile grout.
He could pick off another clump, put it in a glass of water overnite and see if it's still crumbly.
A lump the size of a walnut in water for three days should be harder than the nut it resembles.
SamT
Sam, I don't know if it was humid, rained, seismic events ect. I have no idea where he is.
I did look it up & find this. No mention of any other water hardening later. Who knows, maybe there's something to be gained by it. Can't hurt I guess, but the first few days are when most cement based products should be kept moist and that apparently was not done unless I missed it.
http://www.sacstucco.com/pdf/w1kdata.pdf
WESTERN 1-KOTE
A fiber reinforced, modified portland cement base
coat.
Manufactured by:
Sacramento Stucco Company, Inc.
(916) 372-7442 Fax: (916) 372-4836
Curing:
The product requires a minimum of forty-eight (48)
hours moist curing. Environmental conditions such a
heat, wind and low humidity all require liberal curing.
Joe,
I addressed this to Shep, 'cuz you are paying attention and he is the one who really should read this.
"but the first few days are when most cement based products should be kept moist"
Absolutely.
However most cement based products are more than a few fractions of an inch thick and are not bonded to a small mesh reinforcing, unlike stucco. And too, the main purpose of the scratch coat of stucco is to provide a rigid backing for the brown coat. The brown coat is the main structural component of three coat stucco applications. It is very important to not let the brown coat dry out for at least 7 days, especially with the scratch coat situation he has.
Someone lets a 3" slab with 6" WWM dry out the first day, they're getting the standard uneducated garuntee; "It's gonna crack."
Know you, that by crack I mean structurally significant cracks and not the typical microcracking that concrete does on its surface.
SamT
Guess he'll know in a year or three what's gonna happen.
Joe H
Shep,
Yeah, the time between application of stucco and curing water is not really a big problem. . . as long as it hasn't been damaged otherwise.
As to freezing, that can be a problem, however, IF, the stucco was dry enough, even that may not have damaged it.
The actual damage happens when ice crystals become large enough to mechanically seperate the stucco concrete.
Take a leaf rake and rake the wall. That'll tell you real quick if you've got problems.
SamT
I would contact the technical reps for the product and give them the exact details (as many as you have) of how it was handled. They'll want to know things like how much water was mixed in, how cold it was when applied, how much time elapsed before it got below freezing, stuff like that. They should be able to give you some good info. Everything comes with instructions, even 2x4s.
Yup, even my sod came with instructions....GREEN SIDE UP!!!!
What SamT said is true.Concrete is funny stuff, half science and half art.I've saved REALLY screwed up jobs by misting it twice a day for two weeks.I'd say just go over your walls thoroughly, tap them, scratch them real hard with something metal, if it looks good it probably is good.Next time you're doing stucco in cold weather come around here and ask before the work starts, we'll give you some tips and tricks.
If it dont get hard in 3 days, it never will. If you can remove it with you fingers and not a hammer, then it time to remove it. I've seen plasters remove bad scratch coats with a hammer and destroy the lath paper at the same time. Thus creating another mess.
Most jobs like this go undiscovered until someone drils it or pound on it and starts to hear sand and gravel running inside the wall.
To answer the unknowns...I'm in Albuquerque, NM. The day the guys started putting the scratch/brown coat on it was in the 40's and dry. Probably in the high 20's to low 30's at night. The stucco sub has not been back to mist/spray the base coat (Western 1-Kote is actually a scratch/brown coat ... the system is a 2-coat system) at all. The sub says he will come back and spray/mist later. It has been going on three weeks now....If I scratch the surface, it seems hard. If I pull off a chunk, I can crush it to powder. My previous experiences with stucco/concrete have led me to believe the first few days everything needs to stay warm and misted/sprayed or else it won't cure. I'd like to get this cleared up before the stucco sub does the color coat...Thanks for the input. I guess I'll take a chunk off the wall to the local stucco supply house and get their opinion as well...
I guess I'll take a chunk off the wall to the local stucco supply house and get their opinion as well...Good idea. It seems to me that you shouldn't be able to pull a chunk off of the wall. I'd definitely get a professional opinion.
Shep,
"The temps here have been pretty cold and I'm beginning to wonder if the stucco didn't freeze" 66874.1
"40's and dry. Probably in the high 20's to low 30's at night." to 66874.26
That same night? Didn't have time to dry out enough to prevent freeze damage IMO. The mud would have to be really dry to not be damaged by freezing. The ice pockets would be too large to bridge during the crystal forming stage, (hydration.)
Wasn't moist AND WARM long enough to develop enough strength to resist freeze damage either.
My conversation with Joe was only in regard to dryness not freezing.
SamT