BajaNomad

Chalky White on Painted Patios

LRW - 3-27-2009 at 09:08 AM

Our home is about 2 years old now. Most of it is stained stucco (colorant added), however the patio overhangs are painted. A 'chalky white' has started coming through the painted areas. We are a block off the ocean and thought maybe salt....but it isn't appearing in any specific area, etc.

Asked the builder...'no se.' Can anybody tell me what this is and / or what a simple fix is. They are in an area not readily accessible for repainting.
Thanks,
L.

White

tehag - 3-27-2009 at 09:46 AM

Probably salitre (salt intrusion). Simple fix — keep your paint handy. If there is no barrier placed into footings and under concrete pours, there isn't much you can do about it. There is a product that can be mixed into stucco or concrete to minimize wicking of salty ground water, but if you can't get it between the water and the paint, forget it. There is no effective retrofit. If you do find a cure, please go public with it.

BigWooo - 3-27-2009 at 10:01 AM

We used to get that on our last place. It would leach through random places in the color coat on the walls, we didn't have paint then.

Our new house is painted, but from our experience with the color coat, we knew the white stuff would most likely cause problems with the paint. After a lot of research we decided on a primer called "EFF-STOP® Acrylic Masonry Primer/Sealer" from Dunn Edwards. Had to import it, but well worth the effort. So far three years directly on the coast and no white stuff. Don't know if it's just luck or the primer, but I tend to think it's the primer.

Unfortunately for your situation, I think the primer has to be applied directly to the stucco, not over existing paint. If it's somehow possible to remove the paint, then prime, it may be what you need.

[Edited on 3-27-2009 by BigWooo]

LRW - 3-28-2009 at 09:59 AM

Thanks...will check out the primer. Funny thing is it is nowhere except on the underside (part we look at) of the patio ceilings.

L--

DENNIS - 3-28-2009 at 10:04 AM

I think this may be your problem:


http://www.cement.org/tech/faq_efflorescence.asp

Bob and Susan - 3-28-2009 at 01:59 PM

i think the rof is leaking

seal it with comex top coat

Diver - 3-28-2009 at 02:37 PM

Quote:
Originally posted by Bob and Susan
i think the rof is leaking

seal it with comex top coat


My thought too; excess moisture behind the paint is coming from somewhere ?

Pescador - 4-1-2009 at 07:38 PM

It is definately efflorescence. You can read a long treatment about this stuff if you use the search feature here or you can google it up.
We have an area where it comes back up whenever we get water in the vicinity and it comes back up. There are treatments for this and time does seem to help, but I had a pad at my old house that did that for the whole time I was there.

LRW - 4-1-2009 at 08:04 PM

Thanks to all for your input. We now think it is efflorescence..and unless we get hammered with a bunch of winter storms where we can see it leaking, will treat it otherwise.

L--

Diver - 4-1-2009 at 08:21 PM

Once you solve the problem, use a dilute muriatic acid solution to remove the efflourescence then prime and paint; or not !?