Stucco is a great product that can be used on both interior and exterior applications and is known to be one of the most beautiful finishes out there that are available but knowing what stucco is, what it's made of and how it works is another story and is what this articles going to talk about to give you a better overall idea of these points.
What Is Stucco?
Stucco is a type of siding that is cement based and provides a seamless finish on a wall and has many different textures and colors that can be achieved. There are two basic types of stucco systems and these are commonly known as a three coat stucco system and a one coat stucco system (a.k.a. 2 coat system).
The Two Types Of Stucco Systems...
The two different stucco systems are really just different processes that take place in a certain sequence and doesn't really have anything to do with different stucco materials being used, except for the base coats.
Even though the base coats are made differently, they are very close to the same thing and the basic elements of Portland cement, lime, sand and water are still used but the base coat for a one coat stucco system has other additives added to that basic mix, that's pretty much the main difference, in a nutshell.
The two different stucco systems can have a cement-based finish coat or an acrylic finish coat applied to the base coat(s) and there really is no difference when it comes to what type of finish you can use on either system, the difference really comes down to the base coats and these are small differences, which we will get into.
What Is Stucco Made From?
Three Coat Stucco System: Today's stucco is made from Portland cement, lime, sand and water in it's most basic form and is still what a lot of stucco contractors use because of the strength and being a cost effective formula, in addition.
Plastic cement is usually used instead of a common cement and lime because it has a predetermined amount of lime added to it already which makes a perfect consistency for plaster mud after sand and water is added. Plastic cement is basically common Portland cement and lime mixed together in one convenient bag.
The basic recipe for stucco base coat is three parts sand to one part cement (plastic) and approximately 3 to 5 gallons of water, depending on the consistency you're going for. I made a post that goes into much greater detail on how to mix stucco base coat and is worth checking out if you are looking for more information on the topic.
One Coat Stucco System: One coat stucco is a little bit different than a three coat stucco system and uses a much thinner base coat (3/8") so the cement used is a little bit different than a "standard stucco mix".
The base coat for a one coat stucco system consists of Portland cement, chopped fiberglass, acrylic additives, sand and water and is modified like this because it is much thinner so the fiberglass particles and acrylic additives give it a little bit of strength and makes it a little bit more water resistant than traditional stucco base coats. Here is a product page for Omega Stucco's (One Coat) base coat that will give you a little more info on what's in it.
Finish Coats: The finish coat is the final coat that goes on a stucco wall and is usually colored (integral coloring added to product) and can be a standard cement based finish or an acrylic type of finish.
A standard cement-based finish will use white Portland cement, sand and water that is mixed with a color packet (powdered) which tints the finish product to achieve the desired color that you want. Typically you would choose from a stucco color chart to achieve the desired color your going for but you can also order a custom stucco color, if you would like.
An acrylic type of finish is a lot like paint but has aggregate included into the mix that gives it that "textured look" and is comprised of acrylic, crushed aggregate (like crushed quartz) and color pigment.
The base for acrylic stucco is usually white and a color bottle (liquid) is mixed to the base to achieve the desired color, which is also chosen from a stucco color chart. Acrylic stucco finishes have much more vibrance to them and are brighter in nature and you can custom color match just about any type of color, even specific paint manufacturers colors.
Interior Stucco VS Exterior Stucco:
Exterior stucco and interior stucco are two completely different things that use different materials but have the same basic principles when applying the material, mixing the material and coloring the material.
Exterior stucco uses materials that can withstand the elements that are commonly found outside and two of the most damaging elements include rain the sun's rays. Paper is used on the outside of the building before the base coats are applied, in order to protect the wood, insulation and anything else on the inside of the house from getting wet.
Interior stucco is a little bit different and does not require the waterproofing that an exterior stucco system requires, the one exception to this would be in bathrooms or areas of the house that are going to be exposed to water but for the most part you don't have to worry about this when it comes Interior stucco.
Interior stucco is more commonly referred to as "plaster" by most people and not stucco (in most cases).
There are different types of interior plaster that can be used and each type has its own advantages and disadvantages when it comes to applying the material, cost of the material, the overall design and look of the finished product and how durable it is but I don't want to get too deep into that on this particular article.