It's not so much that stucco is a bad material, it's that it is often installed improperly which can lead to water problems, mold, and the rotting of your walls. Stucco absorbs water like a sponge, and making sure that water can adequately drain out and dry is crucial to preventing rot problems. Stucco should never be an afterthought when designing and building a home, as the installation details are critical to getting right in advance in order to avoid these issues down the line. The conventional way that stucco has been installed for years is the problem. Most exterior stucco walls have a buildup of a half-inch plywood or OSB sheathing, a weather barrier like Tyvek house wrap or asphalt-impregnated tar paper, A metal lath to attach the stucco, and then a three coat stucco layer. Stucco is a reservoir cladding, meaning it absorbs water. If we can all agree that stucco acts as a sponge, then we can agree that any surface behind the stucco will get wet. There's just no avoiding it. If there isn't a place where water can drain out and dry behind the stucco layer, then the wall becomes saturated. Over time, excessive water and moisture inundate the weather barrier and hydrostatic pressure drives water through any seams and penetrations in the membrane and into the sheathing and wall cavity, resulting in mold and rust since this moisture gets trapped with help from the insulation which impedes the drying process. Vapor drive can also exacerbate the problem, especially if the sheathing is already saturated with water, leading to more moisture and water problems near walls as the vapor will condense on the backside of the sheathing. Older stucco homes actually do quite well and have lasted many decades. This boils down to a few things. No insulation, lots of air movement, and solid wood sheathing. Older homes were often not insulated and had many air leaks. Normally we want to avoid air leaks wherever possible in newer homes. However, this combination allowed a lot of heat and airflow to dry out any areas that got wet behind the weather barrier. Additionally, the 1x6 or 1x8 solid wood shiplap sheathing has a significantly greater capacity to store water compared to plywood and OSB. As soon as we started preventing these walls from drying, we ran into problems. With this in mind, we need to make sure that the wall details we're using are providing this well-needed drainage point. On the exterior sheathing, I would recommend using a self-adhered vapor permeable membrane like Delta Vent SA. This will not only provide the weather barrier, but also a highly effective air barrier. On top of this, install a few inches of Rockwool Comfort Board insulation. This is a vapor permeable hydrophobic rigid insulation that will prevent water from condensing on the backside of the sheathing, and improve thermal resistance of the wall assembly. On top of this, you'll want to install a double-sided drainage plane for stucco applications. I like to use the SturCavity drainage plane from MTI, but Delset also makes a dimple mat product for stucco called Delta Dry. On the side that the stucco will be installed on, there will be a layer of fabric, which helps prevent the stucco from clogging up the micro-cavities. Over this you can install a typical metal lathe and then a three-coat stucco. In this system we not only have one drainage plane but two. One is located directly behind the stucco which will help shut the bulk of water and the other is located on the opposite side facing the rock wall comfort port helping to drain any water that happens to make its way behind the primary drainage plane. This is an amazing detail that will ensure that your home remains protected from water for the lifespan of the structure. Now, if you're on a more limited budget, I'd recommend using Zip System Sheathing instead. Zip Sheathing has an integrated weather barrier on one face of the OSB, and the joints are sealed using flashing tape. This is still a really robust weather barrier and creates a good air seal as well. On top of the zip sheathing, install Delta Dry and Lath which has an integrated synthetic lath and then we can install the 3-Coat Speco right on top of that. You could also use another drainage mat of your choosing, just as long as it's double sided. Liquid flash the sill plate to prevent water intrusion and improve air and bug sealing. Then we can close off the top and bottom of the wall with a bug screen, which still allows continuous airflow. We also want to make sure that we're flashing the base of the wall with some metal flashing to kick out any water that gets behind the drainage mat and further protect the sill plate. Now, you might be asking, what do we do about window and door openings? These are really critical areas that you need to get right. At the sill, we need to make sure that any water that gets into the jam is able to escape. It's not so much about making sure that water can't get in, but it's more about making sure water can get out. In this detail, we have a sloped sill and a back dam to prevent any water that may have gotten past our flashing from entering into the interior. Then we liquid flash the entire window opening a couple inches past the edges to get a continuous water and air barrier. Then we install inch to inch thick shims at the base of the window to provide a small drainage gap so that water can drain away from the sill and down the drainage mat. We don't want to tape or caulk this spot, otherwise water will get trapped inside. This also provides a good spot to attach the sloped sill trim to divert water away from the window and to protect the nailing flange. Then we can install Delta Dry and Lath below, along with the bug screen and then the three-coat stucco layer. At the window head, we need to be installing a metal drip cap flashing over the flange. The majority of water intrusion occurs at the window head, and so this is some cheap insurance against water penetration, and again to kick out water away from the window. We then need to seal the top of that edge with a strip of zip flashing tape to keep water from getting behind the metal flashing. Then install the drainage mat right on top with the bug screen and then the three-coat stucco. Now, if you're still concerned about the water problems associated with stucco, James Hardy makes a fiber cement board product called Reveal from their Aspire Collection that almost looks indistinguishable from stucco, especially if you use a textured paint. It's a panel system that is installed similar to traditional siding, over rain screen battens to provide a drainage plane, and then mechanically fastened to the wall system. The benefit of this system is that it simplifies the wall assembly and installation, which can be beneficial if there are concerns about the quality or skill of workers in your area Most builders or contractors with a small crew should be able to work with this product without needing to use a stucco or siding contractor. For more detailed information about stucco and other claddings, please visit the link to my articles in the description below, and make sure to sign up for email updates so you get notified when a new article is released. If you found this video helpful, please leave a like and subscribe. Good luck on your projects. Cheers.