Stucco is a gorgeous material for home exteriors, but can you stucco over the expansion joints? You want a seamless appearance and worry that the lines of expansion joints will make your home look unsightly. We've researched to find out the answer to this question for you.
Legally, most building codes require you to have expansion joints in your stucco, particularly if you're stuccoing over lath. So your builder will probably push for you to have them. But some builders are willing to stucco solid if you sign a waiver that will not hold them responsible for any cracking of the stucco surface. So the short answer is yes, you can stucco over expansion joints, but there is more risk of cracking.
Let's take a look at this a bit more in-depth; then, we'll answer some additional questions. We'll talk about if stucco expands and contracts, what the difference is between expansion and control joints, if you lath over expansion joints, and if you can stucco without lath at all. So please, keep reading to find out more.
Can You Stucco Over Expansion Joints
Expansion joints are the vertical and horizontal joints that you see cutting across the surface of a stucco finish building. They can be placed somewhat creatively, as in this modern home above, so that they become part of the design. However, some folks really do not want lines crisscrossing their stucco finish and want to know if they can stucco over the joints.
What Expansion Joints Look Like
This image is a great example of what we mean when we talk about expansion joints. The metal grid is the lath to which the stucco material adheres to. This is run on the surface of the home. The solid metal W-shaped piece is the expansion joint. You can see in this example that it is not stuccoed over and that a thin line remains cutting horizontally across the surface.
Why You Don't Want To Stucco Across The Expansion Joints
The purpose of the expansion joint is to allow the stucco to expand and contract with temperature changes. This helps keep the stucco from cracking all willy nilly. One of the places cracks are likely to happen is at the corners of windows and doors, making them even more noticeable. Expansion joints are basically like pre-cracking your stucco. The crack is already there, so your surface remains pristine.
In this home, the joints are in line with the window corners, both vertically and horizontally. You barely notice them once it's installed. But if you had tendril cracks out from the window corners, you would notice it, and it would leave your home vulnerable to moisture as well. This is a good argument for not stuccoing over your expansion joints.
Why You Might Want To Stucco Over Your Expansion Joints
If aesthetically, the idea of a bunch of crossing lines on your building is unappealing, and you don't mind the natural hairline fractures that may occur in your stucco over time, then skip the expansion joints altogether. You can stucco over masonry without lath, or you can install lath without the expansion joints.
Here we see lath butting up next to the interior steps, and no expansion joints are present. In this case, the stucco will be applied to the metal grid, and no expansion joints are used.
Examples Of Beautiful Stucco Work
We thought it would be nice to throw in a few images of gorgeous stucco work, some with visible expansion joints and some without. This way you can decide which way is your preference.
This gorgeous home with white stucco siding uses expansion joints. The pristine clean lines work with the clean lines of the architecture.
This home does not utilize expansion joints and has a flat stuccoed surface. But do notice the arched windows, which provide less of an angle for cracking.
This is an interesting idea. They've used a bit of Tudor trim to help hide the expansion joints beneath the wood. This is a clever way to play up the expansion joints rather than downplay them.
Does Stucco Expand And Contract?
Stucco will expand and contract with a temperature change. And because different areas of your home heat and cool at different rates due to direction and elements, that expansion and contraction can be different, too. This is why you find expansion joints in your stucco because without them, the water might find its way into cracks which can damage the sheathing of your home below the stucco.
What Is The Difference Between Expansion Joints And Control Joints?
Expansion joints are vertical or horizontal joints used in stucco or masonry that are left free of mortar. These joints allow for expanding or contracting due to thermal and moisture issues. Control joints, on the other hand, are used for concrete applications. They typically run vertically and are filled with mortar, and have a bond breaker on one end. This allows for the control joint mortar to expand as the concrete or masonry contracts, keeping cracks from appearing. Both are important in construction processes.
Do You Lath Over Expansion Joints?
The expansion joints are there to create a place for shrinkage and expansion. Lathing over them would be contradictory to their purpose. You need that gap to keep dangerous cracks from occurring in your stucco finish. According to the International Building Code, lath must be cut behind the joint and wire tied to the sides of it. Therefore, your stucco finish would not cross it.
Can You Stucco Without Lath?
Stucco can be applied without lath. The trick is having a well-preferred substrate surface. If it's done right, you remove the possibility for water to get between the stucco finish and the wall below. If lath has adhered incorrectly, water can be an issue. But one issue with stuccoing without lath is if the wall is not plumb and stucco applied at different thicknesses, it can debond.
One time you will always need to use lath is when stuccoing over an older block building. There are too many variables from the years it's been standing to forego the use of metal lath.
Expanding Your Stucco Repertoire
We hope this post has helped you see how stucco expansion joints serve a purpose. Whether you want to use them to prevent cracking, or don't care about a little organic cracking, is up to you. But either way, a stucco home is simply gorgeous and relatively easy to care for if installed correctly.
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