Exterior Stucco Finishing

September 1, 2021 9:36 AM

What is the current best-practice for finishing exterior stucco on an old (1920's) home? I've recently had a repair done and need to finish the patches. I think I'd like to do a traditional whitewash as opposed to a latex-based paint, but I don't see a ton of step-by-step resources with product and upkeep recommendations. What do the preservation-minded professionals do?
posted by Think_Long to Home & Garden (4 answers total)

The longest-lasting way to finish stucco is by applying a finish coat of tinted stucco. Latex paint on stucco...works...but tends to flake off very easily. It's really hard to get good adhesion and once you get moisture in the stucco behind the paint, you're done for. You can look at old photos of your house (if possible) or other stucco houses in your area for historically appropriate finishes. The downside of doing this is that it costs more money upfront but it will last many decades if done well.

I don't think there's anything *wrong* with whitewashing stucco but my guess as to the reason people don't do it much is...like, why not just mix some lime into the final coat of stucco? You're putting on a cement-based product so anything that's compatible with cement, just mix in, and then you don't need to worry about reapplying it until the stucco breaks.
posted by goingonit at 9:58 AM on September 1, 2021 [1 favorite]

If part of "preservation" is keeping the look of what a 1920's home would have originally had in your area, you will need to look to local resources for this instead of askme. There might be a local historical society, or talking to the reference desk of your local public library should be able to point you in the right direction.

Where I live stucco is either finished with a color coat synthetic stucco, or more traditionally a lime plaster. But both of these need to be compatible with the stucco underneath! Latex paint is a definite no (many people paint over stucco but it's not a good idea for several reasons) and I've never heard of whitewashing stucco, but maybe the type of stucco where you live is different.

It doesn't sound like you know what type of stucco you have originally or what the patches are? This is the first thing you need to find out. It seems like whoever you hired to do the patching didn't discuss this with you, I would check with someone else on this. You might also verify that the patch materials are appropriate to use with the underlying stucco. Then you use whatever is most compatible with that type of stucco.
posted by yohko at 12:09 PM on September 1, 2021

https://www.limeworks.us/ Sells products but is also very helpful.
posted by sepviva at 6:28 PM on September 1, 2021

Whitewash is used to make something more weather-resistant, like wood. Stucco is already weatherproof. It won't hurt anything except needing to wash it off if adding a new coat.

You can't match color coats. If you don't want the patches to show, you need to cover the entire surface, traditionally with a color coat. If you don't want to spend that much money, you can just leave it the way it is (caulk cracks though).
posted by flimflam at 7:04 PM on September 1, 2021