Updated for 2020! It’s been nearly five years since I wrote this series about the faulty installation of manufactured stone veneers, and the havoc it is causing unsuspecting homeowners. I decided it was time for some new information so I’ve updated things with new images and information.
It’s all the rage these days: Fake stone siding, manufactured stone veneer, stone veneer, cultured stone, or whatever you choose to call it. I personally stick with the term, manufactured stone, or just stone veneer for short. The product is used as an accent on the front of a house (or it can be the whole siding in some cases). With it, you can give your home that mountain cabin look, right here in suburbia. Manufactured Stone Veneer (or Adhered Concrete Masonry Veneer or Adhered Manufactured Stone Veneer, as it’s technically known) is a thin, man-made siding made to look like natural stones or rocks.
It’s basically molded concrete that looks like real stone.
Stone veneer is normally installed over the wood framing on a home. But when installed incorrectly, it will let water in next to your wood framing, trap it, and wreak havoc on the structure of the house. And so far, I’ve yet to see an install done correctly in Louisville, Kentucky (or anywhere for that matter).
LEAKING MANUFACTURED STONE VENEER CREATES MOISTURE PROBLEMS
In 2012, I was called in by a homeowner here in Louisville, Kentucky, to look at his 2-year-old custom-built home. The family had tried to hang curtain rods on the front wall, and they discovered that their drywall was too wet and mushy to hold a plastic wall anchor. They had no clue as to why things were wet. I was able to track the problem down to the manufactured stone veneer siding on the front of the house. The builder had omitted all of the important flashing details with the install. That day was the beginning of a 2-year fight between the homeowner and his builder. During that entire period, his dining room was blocked off and unusable because of the extensive wood rot and mold problems that came along with it.
The result: Attorneys were hired and things got ugly. The builder eventually repaired all of the water damage, stripped all of the manufactured stone off the home, and replaced it with real stone (they did not try to install manufactured stone again). The final cost of the repair was close to $80,000.00.
Moisture intrusion experts have made a connection between manufactured stone veneer and traditional stucco (stucco homes in Louisville, Kentucky are very rare to find). When problems arise from a botched install, a house with manufactured stone veneer shows the same moisture-related issues as a house with a botched stucco system. Water leaks behind the cladding and gets trapped. Then, the house rots. In fact, one of the brightest minds in the world of building science, Dr. Joseph Lstiburek refers to manufactured stone veneer as “lumpy stucco.” He has a great article that you can read here: Stucco Woes.
Most manufacturers of ASMV are members of the Masonry Veneer Manufacturers Association or MVMA, who are now under the NCMA (National Concrete Masonry Association). I know, enough with the acronyms already. The MVMA puts out an installation guide that is considered the “end-all-be-all” of how-to installation guides when it comes to manufactured stone veneer siding. When I am performing home inspections in Louisville KY, I refer to that guide and its details to show my clients how things should be done. The problem is that I have never seen a home that has manufactured stone installed as the guide says it should be. Almost every detail is usually skipped–and we all know that the devil is in the details. You can download the MVMA guide here.
IDENTIFYING MANUFACTURED STONE VENEER
I’ve had a number of home inspectors and homeowners write to me over the years and ask, “Is this manufactured stone?” Let’s take a look at the ways you can determine if your cladding is manufactured stone.
Manufactured Stone Veneer Installs:
- Have cut edges on the stones. Most MSV installs will have at least a few stones that have been cut to fit into the wall. Look for those pieces. Usually, you can see the small pebbles in the casting from the manufacturing process. See the image below where I wet the edge to have the pebbles show up more clearly.
- Manufactured Stone Veneer will be stuck to the surface of the wall, hence the technical name of AMSV (Adhered Masonry Stone Veneer). You should be able to see the manufactured stone veneer pieces stop a few inches above the grade (soil or mulch). The reality though, is that it hardly ever does.
- Just about any building constructed in the past 30 years will use manufactured stone as opposed to real stone. It’s just too costly to use real stone or even real stone veneer. There are some exceptions, but generally, this rule holds true.
MOISTURE INFILTRATION WITH MANUFACTURED STONE VENEER
A wise man once told me that water and women can be lumped into the same category: They both always win. Never is that statement more true than when it comes to the manufactured stone installation on your home. Water will find a way in. It will seep in around the cracks, and it will be absorbed into the mortar and chunks of concrete. You didn’t think this stuff was waterproof, did you? It’s colored concrete. It absorbs the rainwater, the sprinkler water, melting snow–everything. What we must do as construction professionals is design and build a wall system that can control the water and not let it reach the structural framing of the house. The moisture will get past the stone veneer; it’s what happens next that is vital to the integrity of your house. Every type of siding (or cladding) needs to be able to drain the moisture that gets by it.
Take brick veneer for example. Building codes have required a 1″ gap (brick manufacturers recommend a 2″ gap, by the way) between the sheathing on a house and the backside of the brick. When the water gets absorbed by the brick (No, brick veneer is not waterproof either), that gap is in place to make sure the water doesn’t soak the wood framing behind it. It gives the moisture a path to escape at the base of the wall, via weep holes. Take a look at the brick wall detail below, and you’ll see the drainage plane present. The air gap is the green-colored area. This allows the moisture a path to escape, and more importantly, a decoupling of the brick and wood so that capillary action cannot draw the moisture into the wood framing.
I wrote an article about a home with a failed stone veneer and a failed brick weep system that caused catastrophic damage that you can read here (Failed Manufactured Stone and Brick Veneer on New Construction Home.) If you would like to see what the inside of a brick wall cavity looks like, you can get a general idea with this video I shot of a brick veneer wall assembly. Video of Brick Veneer Wall Assembly
FLASHING DETAILS MAKE OR BREAK MANUFACTURED STONE VENEER
Manufactured stone veneer is typically installed on top of the wood sheathing on a house. It doesn’t have an air gap since it’s adhered or stuck to the wall, and is not resting on the foundation wall (like brick veneer). If you want a trouble-free install of manufactured stone, you must create a path for moisture to drain and a place for it to escape at the base of the walls, windows and doors. If you do not have a drainage point, the moisture will simply build up and rot out the base of the structure. I’ve never seen a home with an escape point, (known as a weep screed) installed, and I look at new construction homes every week. The builders are simply not installing them.
Check out the wall detail below. I’ve highlighted the weep screed in red at the base of the wall. This small piece of flashing will allow any moisture that has built up behind the manufactured stone a place to drain and will allow fresh air an entry point to dry things out.
PROPER INSTALLATION OF MANUFACTURED STONE VENEER SIDING
Hindsight is always 20/20, and now that the problems with manufactured stone are coming to light, we’re getting smarter about it from an engineering standpoint. Unfortunately, the installation on homes is still all messed up. If you actually read the whole MVMA install guide, (You did read it, right?) you’ll see that at the end of the document there are alternative methods for building the manufactured stone veneer wall system. These include a drainage mat or furring strips mounted to the sheathing of the wall. By adding these details, you will essentially create an air gap between the house and the concrete veneer. Sound familiar? That air gap will allow for moisture control and drainage to occur without the risk of the moisture soaking into the wood structure of the home. “Is anyone doing this?” you ask. They’re not doing it here in Louisville, or anywhere else I’ve been to inspect manufactured stone veneer installations. It’s likely going to take some really big lawsuits to get the ball rolling on correct installs. The process requires more planning, more work, and careful execution to pull off.
Below is a detail for the use of a drainage mat used in place of the furring strips. This method also creates that needed air gap between the manufactured stone layer and the structure of the home.
INSPECTING YOUR HOME FOR MANUFACTURED STONE PROBLEMS
f you have this material on your home and have questions feel free to contact me. More than likely, your home’s manufactured stone veneer was poorly installed. I hate to say it, but I’ve never inspected a house that had a proper install. There are ways to take minimally invasive moisture readings from the inside and outside of the home to get a better idea of what type of damage may be occurring on your home. If you’d like more information on this process, just give me a call and we can talk. I have traveled extensively to help clients with manufactured stone issues, so don’t think that just because you are not in the Louisville, KY area I can’t help.
When big problems pop up with a house, we can usually trace their origins back to a bunch of small details that add up to the current train wreck. That seems to be the reoccurring theme with the manufactured stone installations that I am seeing now. When the home is missing all of the critical flashing details like weep screeds, kick-out flashing, and casement beads, how can one assume the assembly will perform OK?
Anyone who’s ever spent time on a job site knows the attitude of most construction workers today. Over the many years I’ve worked in the trades, one of the more popular things to hear was, “Looks good from my house,” or “We ain’t building a piano.” That’s a creative way of saying they just don’t care. They do not care if you have problems later on. If it’s ‘good enough’ to get things cleared, and if it’s ‘good enough’ to get them paid, let it roll.
MORE STONE VENEER ARTICLES THAT MAY HELP YOU.
I have written many more articles on the subject of manufactured stone veneer. There are two more parts to this series and many case study homes of real-world failure. If you have a question about stone veneer you can ask that below and I’ll get back to you asap.