More Than You Wanted to Know About Coloring Stucco
By At Home Alterations on Oct 01, 2011
Last week when we wrote about changing our roof color we mentioned painting the stucco. We said we've heard painters say it's A-OK but we've heard the opposite from other people. After some really helpful comments on that post we decided we needed to know more about painting stucco and what alternatives are out there. It quickly became apparent that there's lots of differing, incomplete, or generally disjointed information about coloring stucco. After finding several good sources of information about specific ways to color stucco, I thought I would put together an overview of what I gathered... partial for my own sanity but partially for anyone else out there trying to find out more information. Since this is just a collection of information, I sited my sources as best as possible! I hope this is helpful for someone out there!
What is stucco
Stucco is a masonry product that's used on the exterior of houses. It's made of portland cement, limestone, sand, and water, a consistency similar to mortar or concrete, minus the aggregate (pebbles and small rocks). It's a strong surface that can take a beating and still last several decades (ours is 90 years old and doing fine). One of the unique properties of stucco is that it can absorb water into it's pores and evaporate it just as easily. There's a barrier between the stucco and house to ensure the water doesn't come all the way into the walls. If water ever gets that far into the stucco it just runs down to the bottom of the wall and evaporates from there.
The stucco that was put on houses around the same time period as our house (1920s) were almost always white in color but new stucco can be created in a wide range of colors by adding pigment to the mix before it's put on the house.
If your house already has stucco and you'd like to change the color there are a number of ways to do it from adding a new layer of colored stucco, staining the stucco, adding a super thin layer of stucco, or by painting over the surface. Each has their pros and cons (some have BIG cons) that are listed below.
To restucco or redash means to add a new layer of stucco over the top of your current layer. It's troweled on in the same fashion as the original and you're left with a new layer of stucco. The new stucco can be colored as it's added so you're left with a new color house when all is said and done. Because the new stucco is colored all the way through, there's no worry of the color fading or wearing off. A new texture can also be created with the new layer of stucco. If the current stucco is in bad shape - either worn down, painted, or has been colored by any of the after-mentioned processes - it will have to be sandblasted. Sandblasting roughs up the surface and removes paint or other layers that have been added. The result of doing a restucco is a strong surface that will remain true to it's new color and last a long time. This is the best way to update or change the color of your stucco but unfortunately it's also the most expensive.
Recoat: Every 15-30+ years
How it affects stucco: Adds a new layer of stucco with the same strength and breathability
Fog coat/cement paint
Fog Coat (updated product is called Allegra II) is made from the same materials as stucco (portland cement, limestone, and water) but without the sand. Because it doesn't contain sand it's very thin and can actually be sprayed onto existing stucco like paint and will keep the original texture of the stucco. But, because it doesn't contain sand it goes on very thin and does not add much strength to the wall. Fog coat is great for revamping stucco to it's original color, evening out colors, and covering stains in the stucco. It can also be used to change the color of stucco but I have a slight worry that if the fog coat wears down at all the original color will show through. Fog coat is one of the cheaper ways to change the color of stucco and lasts longer than paint but shorter than doing a restucco job.
On a side note, I saw the terms Fog coat and cement paint used to describe essentially the same thing - cement, limestone, pigment, and water combined to make a paint like substance - so I grouped them together. There wasn't much information on cement paint, it's either a loose term or a product similar to fog coat but that contains water proof and anti-fungal chemicals.
Recoat: Every 15 years
How it affects stucco: Lets stucco breathe and shed water but creates a slightly weaker surface layer
Lime wash/white wash
Like what Huck Fin had to do to a fence, lime wash (or white wash) is the process of applying a thin coat of lime powder mixed with water (and a few other additives) to a masonry surface like stucco. The carbon dioxide in the air reacts with the lime to create limestone which bonds to the stucco as it cures. White wash is a lime wash with chalk added for a white coloring but there are many other color options for lime wash. Using different ratios of water and lime creates different consistency from a pale water colored look all the way to a thick opaque look. According to one source, once there is a lime wash you can't restucco over it without first sand blasting the lime wash off, it's just not strong enough to bond a new layer of stucco. Lime wash can give a great old-world look to a stucco wall. The cost of lime paint is fairly inexpensive but exteriors need around 5 coats of lime paint so the overall cost (and labor) are higher.
Recoat: I couldn't find any specifics other than "when it begins to wear" but based on the type of application I believe it will last as long as a cement paint/fog coat - 15 years.
How it affects stucco: Creates a strong layer of colored limestone bonded to the stucco that doesn't affect the breathability.
So far every painter I've talked to has said you can definitely paint stucco. While I agree it's definitely possible, there are some big dangers in painting over stucco. First, it creates a sealed layer over the top of the stucco. If done right, acrylic paint is breathable but there can be cases when paint locks the water into the stucco. With no where for the water to go, it finds it way into the walls of the house. When there's water in the stucco, behind the paint, it puts pressure on the paint from behind and will cause the paint to crack or blister. Since stucco is porous it will soak up a lot of paint and can be difficult to get an even coat. Because of these problems, recoat times can be as little as 3 years or as much as 10 years. While paint is one of the cheapest ways to color stucco, it quickly becomes the most expensive because of the frequent recoating. Never use a standard exterior paint on stucco, there are paints specifically formulated for stucco that may perform better.
Recoat: Every 5-10 years
How it affects stucco: Creates a weak layer on top of stucco, can clog stucco from shedding water, should let some water vapor evaporate
Penetrating masonry stains
Masonry stains for stucco are similar to wood stains, the pigments in the stain soak into the pores of the stucco and tint the color. Masonry stains come in two forms, Acrylic-based and solvent-based. Acrylic has fewer VOCs but solvent-based gives a stronger weather protection. Both keep water out of the wall to some extent but still allow water vapor to evaporate and leave the stucco. Masonry stains fade in the sun so look for a product that has extra UV protection.
Recoat: Every 5 years depending on how much the sun fades
Cost: I couldn't find a price but I believe it will be similar to painting or using cement paint/fog coat
How it affects stucco: Fills the pores of the stucco with colored pigment. Should allow breathability but may reduce the pores ability to shed water.
Well I bet that's more than you wanted to know about stucco coloring! As I said in the beginning I'm just gathering information and I'm definitely not an expert! If you have additional information (sources please!) or corrections let me know in the comments and I may add it to the post. We're just beginning our research to make a decision on our own house, but rest assured that whatever we do won't be for a while and we'll definitely weigh what's best for the house with what's easy on the wallet.blog comments powered by Disqus