Santa Barbara over Xypex-enhanced stucco

[craigsw]

Any experience or hearsay on finishing coats over a Xypex-enhanced stucco sold under the name of Tradecraft Waterguard Stucco for a 3-coat application? The material has been on the market in California for about 4 years, and in wetter parts of the US (Florida, for instance) for over 10 years, but so far am having trouble finding any unbiased opinions on it.

Xypex wouldn't normally be used like this, but they came up with some proprietary way to pre-mix it into the base stucco that works. The test data on this material looks like it is very good at keeping water out (approaching 3 hours in standpipe test without wetness on the backside), vapor transmission meets code, and compressive strength is rated at 3452psi versus around 2500psi for standard stucco and that plus fibers in the pre-mix are claimed to reduce cracking.

The main questions are:
1) Does the material do what is claimed?
2) Is it possible to apply a high-quality Santa Barbara finish over it without the end result looking so bad it needs to painted?

Stucco sub says he's not sure he'd want to use it because he thinks the brown coat won't wet thoroughly (due to its water resistant nature) and will therefore reduce work time on color coat and will make it tough to get a smooth Santa Barbara finish.

Vendor (Paragon Building Producs) says this isn't a problem and they have subs doing Santa Barbara finishes over this material (but unfortunately can't point out any projects, claiming they sell through distribution and don't know), but they also say nearly nobody can do a perfect Santa Barbara (citing burn-out and hairline cracking being cosmetically objectionable) and they almost always get painted out as a result. For maintenance reasons, painting stucco is a no-no and owner would like to avoid it. Vendor is willing to supply several bags of pre-mix for stucco sub to try for free in hopes of alleviating his concerns.

Competing vendor (Expo Stucco) whose color coat we will be using (for architectural review reasons) says their product might actually work better over a non-water-absorbing base coat because in their opinion the reason for wetting the brown coat before color coat is not to add moisture to the color coat (which is what the stucco sub thought) but to keep the base coats from sucking moisture out of the color coat. So they think the color coat will stay workable for longer on top of a non-water absorbing base. (As a side note, this reason is also cited by DuPont for why stucco cures better over their StuccoWrap product than over the usual building paper that would suck the moisture out of the stucco.) Expo also says they are about to start selling a Santa Barbara coat with an admix that extends work time, so that would help even more if we could use it.

Stucco sub is still skeptical of everything above, says he's been doing this for 17 years the old-fashioned mix-your-own stucco from PC and sand way.

Any ideas who is right and why?


Background info:

Short story is that this Waterguard Stucco is being viewed as a backup means to ensure no leaks inside of building given mess previous GC created.


Long story:

Previous GC blew this job through poor relations with subs (failure to pay, etc.), failure to get work done on timely basis (project is 2+ years into construction), fraud, and many other reasons.

Net result as far as waterproofing is concerned is that exterior doors and windows took 5 months for installation by which time the flashings were UV-exposure damaged. Damage was particularly bad on south and west sides of house, generally sills were the worst, but the few inches close to the windows and doors was is good shape because they are recessed about 5 inches from the outside of the wall due to 13-inch thick ICF wall construction. So we layered in additional "Jiffy Seal" (really Carlisle wall cavity system) 9" flashings (polyethylene with 40mil asphalt stick/seal backing) around sill, head, jambs underneath the old material to stop any leaks through sun-damaged areas. Windows and doors are fiberglass framed with aluminum brickmoulds. As added precaution, we installed backer-rod as 3-way bond breaker and caulked heads and sills with polyurethane recommended by local sealant distributors.

Overall wall system construction is ICF (about 8000 sf wall area of Eco-block, 8 inch concrete core) with a small amount (about 300 sf wall area) of upper-level wood framing, but no sheathing on exterior of wall framing as upper framing is double-framed around sheathing in the middle to match ICF wall thickness. All lumber used in walls and door/window bucks is PT 0.17pcf borate, so it's less likely to rot or became termite food unless it gets wet repeatedly and the borate leaches out. Building wrap is 2 layers of Tyvek StuccoWrap. (The 2.5 inches of EPS foam in the ICF forms should have already been pretty good for waterproofing, so the 2 layers of Tyvek are an added precaution.) Moistop sill aprons were used under the sill layer of Jiffy Seal as suggested by stucco sub.

We have to apply stucco imminently as the 120 day UV exposure limit (cited by DuPont in their literature) will be reached in early to mid October. (As to what's taking so long, that leads to another story about the trusses being built improperly and the truss manufacturer refusing to take responsibility for the problem.)

[Dick Seibert]

It sounds to me like you are walking into a mess, in more ways than one. I wouldn't touch this without all kinds of liability releases. First of all, you can't waterproof the surface of any stucco, any attempt to do so will fail. I've heard of Xypex, but would steer clear of it, listen to your plasterer. I agree that all Santa Barbara finish stucco cracks, I do it and advise the clients that it is going to crack, and get a signed release from them, but cracks have nothing to do with leaks. I much prefer a sand finish, or a knock-down dash (never do a texture, it looks cheap).

Here is a link to see what a Santa Barbara smooth finish looks like, I bet a lot of these Easterners and Southerners don't even know what you are talking about. http://www.merlex.com/extstuc_santa.htm Go to FAQs in the top of the link, and select "Textures" and scroll down to the bottom. What they are calling "Lace" finish we call "Texture" finish, what they are calling "Float" finish we call "Sand" finish. Amazing the difference in terminology between Southern and Northern California, to say nothing of the rest of the nation (and world with Chippy). After clicking on "Textures" click on "Gallery" in the same drop-down menu that you found "Textures" in, and click on Picture #4 for the best close-up shot (Don't click on the "Gallery" across the top where you found "FAQ"s)