Quikwall Quikwall Surface Bonding Cement thickness

[kebwi]

To those who have used Quickrete Quikwall Surface Bonding Cement, the question of the thread is almost as simple as the title line. How thick did you apply it? The official directions on Quickrete's website are in the range of 1/8". My (current) design calls an extremely weather/water proof surface (more so than even a typical igloo). I'm curious how thick I can build this stuff up.

...and yes, I'm aware of the acrylic fortifier, I'll use it as well.

Related question: from what I can can tell the term stucco simply refers to sand/portland or sand/lime (or sand/portland/lime). I believe I read somewhere that SBC is the same thing but with fiberglass fibers. My question is, SBC is advertised as relatively waterproof. I don't see how fiberglass fibers can do that? I would imagine they only add structural strength, it's not like they are dense enough in the cement to absorb/block/repell water that is penetrating the cement.

Thanks.

[kebwi]

Bump. Just want to know how thick other people applied SBC on their own builds and any opinion on how waterproof it is, with and without the acrylic fortifier I suppose.

Thanks again.

[Tscarborough]

SBC is a type of stucco with acrylic or latex fortifiers integral to the mix. It also has graded aggregate and usually Calcium stearate. The fibers do not help in waterproofing, they provide flexural strength. The acrylic/latex increases bond strength and waterproofing, but the primary waterproofer is the Calcium stearate, which is a fatty acid that repels water, but allows water vapor transmission.

Thick coats of SBC promote cracking, that is why they recommend a 1/8" to a 1/4" max per application.

[kebwi]

Ah, okay. Would a layer of chicken wire between coats help with the cracking issue?

[Tscarborough]

No. Place one coat across and another up and down for best results.

[kebwi]

Are you referring to "brush" direction? I mean, I won't apply it with a brush, but basic troweling application direction?

[ThisOldGarageNJ]

hey keb,
I used the SBC on my foundation and my dome, the foundation was mortared so I just put 2 thin coats to make it look nice and help waterproof, I used the acrylic fortifier in all of it.. On the dome, I used 2 coats about 3/8 right over the vermicrete,, it's almost a year and to date there are no cracks... If you want a smooth finish on it use only the trowel, If you want a slightly rough finish, wipe it with a grout sponge, this also helps you blend different sections.... I put the Terra Cotta color in the dome, my only dissapointment is the color has started to fade, so i'm considering paint in the spring..
cheers
mark

[kebwi]

@ThisOldGarageNJ: So you went to 3/4" with no cracking. That's impressive...and somewhat at odds with what I've heard...but it's very encouraging. Thanks.

[Tscarborough]

The ultimate thickness doesn't matter, what matters is the depth applied at once. For this application you have several things going for you for thicker coats: Small area and few or no right angles or penetrations.

FYI, liquid colorants are junk and will fade. Always use ferrous oxide (powdered) pigments. Also FYI, greens and blues will fade quickly, and dark red is the next worse.

[sjmeff]

I did two coats of SBC w/acrylic fortifier. I believe each coat was about 1/4". About a month later, I applied two coats of stucco paint to further improve waterproof-ness.

In the 5 months since I finished, I haven't seen a single crack and it's kept the water out.

S