Stucco Siding Help - Cracking and Bulging

[Rancher Ed]

I am starting to have issues with the stucco siding on my house and unfortunately know nothing about stucco. For a little bit of context, this is a two-story house built in the late 1970s with brick on the lower portion and the stucco on the upper portion. The roof is in good shape, and there are no cracks in the drywall so I do not think it is a settling or foundation issue.

A small (roughly 2" tall by 3" wide) piece of stucco has fallen off right under the eve above one of the windows. This did not concern me too much and I was planning to try out a DIY stucco repair kit. However, over the last week or two a bulge with a large vertical crack has appeared in the lower 1/3 of the stucco on one side of the house, and a smaller crack is visible on a different side of the house. Attached are a few pictures that hopefully convey what is occurring.

My understanding from some initial research is stucco is usually applied over the sheathing material with some kind of wire mesh anchor system applied to it. This is what I see in the small spot above the window trim, but I am confused on why I can see fiberglass insulation through the large crack. Given my lack of knowledge about stucco I am planning to get a couple estimates from stucco repair companies as a starting point but would appreciate any information or advice on what I am potentially dealing with, things to watch out for, etc.

 

[2manyrocks]

My guess is the wire mesh has rusted through due to water penetration under the window. When the wire mesh fails, the stucco doesn't have the support it needs and that is why it cracked.

One possible explanation for seeing fiberglas insulation is that there is a hole in the sheating under the stucco and you are seeing the fiberglas insulation in your wall. OR there was some kind of repair job in the past where they stuck FG in there as a filler before putting on a top layer of filler.

I don't know if they will be able to really assess what is happening without removing the outer layer of stucco. If it has to be removed to get it back to a solid base, then the question will be how well they can match the repair to the rest of the house.

Those cracks are letting more water in which will make the stucco want to pull away from the sheating.

 

[EddieWalker]

I grew up in the East Bay of California, near Oakland. Every house there had stucco siding. They where all built before OSB or plywood was used for sheeting. Some houses have one sheet of plywood at the outside corners, but a lot of them just had 1x4's cut into the studs at 45 degrees at each outside corner. The houses are wrapped in tar paper with chicken wire, or metal lathe. Chicken wire is very common on stucco houses there. First coat was the scratch coat that stuck to the wire, the second coat was the finish coat.

With all the earthquakes there, this seems to be all the stucco needed to remain in place. It's very rare to see damage like you have in old homes that where built this way.

Cracking means movement. What type of foundation do you have? Has anything been done to modify the roof? It's very common to go into an attic and see part of the roof framing cut away to fit an AC duct, or plumbing line. Almost every house that I've worked on with cracking to the sheetrock is from an issue in the attic. I've never worked on a house with stucco here in Texas.

The other cause could be water, but stucco doesn't really care if it gets wet, unless the framing holding the stucco in place starts to rot away. Termites might do this too. If it's water or termites, you should be seeing a lot of damage on the inside of the house. Water will cause staining, termites leave dirt behind. Both are easy to see.

If a window is not sealed properly, and most are not, water gets in at the bottom of the window all the time. It's the most common place to see bricks cracking on a brick home. The window isn't sealed, water gets in behind the brick, then freezes, and the bricks start to crack. Over time, the cracks get bigger as more water gets into the open areas in winter, then freezes, and then the crack gets even bigger. Something similar could be happening with your stucco?

Depending on the extent of the damage, how long you want to stay in the house, and how much money and time you have, it might be worthwhile removing he stucco and installing OSB or Plywood sheeting to your studs. Then cover it with house wrap and siding. Hardie is my favorite siding. It's easy to install, looks great and it holds paint forever.

 

[JPRambo]

Had a similar problem on the old house. Did not repaint behind the water softener equipment. After/ during removal of the stucco fount all of the wire mesh and the staples holding it to the wall had rusted. The stucco was holding itself to the wall but bulging. Had a local stucco company ( owner lived a block away) fix it.
Southwest Florida and it had plywood and tar paper backing.

 

[Rancher Ed]

My guess is the wire mesh has rusted through due to water penetration under the window. When the wire mesh fails, the stucco doesn't have the support it needs and that is why it cracked.

One possible explanation for seeing fiberglas insulation is that there is a hole in the sheating under the stucco and you are seeing the fiberglas insulation in your wall. OR there was some kind of repair job in the past where they stuck FG in there as a filler before putting on a top layer of filler.

I don't know if they will be able to really assess what is happening without removing the outer layer of stucco. If it has to be removed to get it back to a solid base, then the question will be how well they can match the repair to the rest of the house.

Those cracks are letting more water in which will make the stucco want to pull away from the sheating.

Thank you! The cracks letting in water is one of my major concerns, especially as this has happened right as summer is ending and we are starting to get rain again.

The fiberglass is definitely the wall insulation and not a repair job - I was able to gently poke a knife 4"+ into the hole with no resistance. I wondered about the odds of a hole in the sheathing right where the crack is, but Eddie's explanation of it possibly being installed without traditional sheathing makes sense.

 

[2manyrocks]

Stucco needs mesh for it to mechanically bond to the wall. When the mesh fails, the stucco no longer has anything to hold onto. 27 in. x 96 in. 2.5 Metal Lath Galvanized 4113145 - The Home Depot

A stucco contractor will probably tear off the iffy section, remove the failing mesh, put down new mesh and then stucco over it.

 

[Rancher Ed]

I grew up in the East Bay of California, near Oakland. Every house there had stucco siding. They where all built before OSB or plywood was used for sheeting. Some houses have one sheet of plywood at the outside corners, but a lot of them just had 1x4's cut into the studs at 45 degrees at each outside corner. The houses are wrapped in tar paper with chicken wire, or metal lathe. Chicken wire is very common on stucco houses there. First coat was the scratch coat that stuck to the wire, the second coat was the finish coat.

With all the earthquakes there, this seems to be all the stucco needed to remain in place. It's very rare to see damage like you have in old homes that where built this way.

Cracking means movement. What type of foundation do you have? Has anything been done to modify the roof? It's very common to go into an attic and see part of the roof framing cut away to fit an AC duct, or plumbing line. Almost every house that I've worked on with cracking to the sheetrock is from an issue in the attic. I've never worked on a house with stucco here in Texas.

The other cause could be water, but stucco doesn't really care if it gets wet, unless the framing holding the stucco in place starts to rot away. Termites might do this too. If it's water or termites, you should be seeing a lot of damage on the inside of the house. Water will cause staining, termites leave dirt behind. Both are easy to see.

If a window is not sealed properly, and most are not, water gets in at the bottom of the window all the time. It's the most common place to see bricks cracking on a brick home. The window isn't sealed, water gets in behind the brick, then freezes, and the bricks start to crack. Over time, the cracks get bigger as more water gets into the open areas in winter, then freezes, and then the crack gets even bigger. Something similar could be happening with your stucco?

Depending on the extent of the damage, how long you want to stay in the house, and how much money and time you have, it might be worthwhile removing he stucco and installing OSB or Plywood sheeting to your studs. Then cover it with house wrap and siding. Hardie is my favorite siding. It's easy to install, looks great and it holds paint forever.

Eddie,
I was hopeful you would chime in - thank you very much for your response! Given the age of this house an application method similar to what you have described is not something I have heard of before but it would not surprise me.

To answer your questions:

• Foundation is slab on grade.
• Nothing has been done to the roof since it was replaced roughly 8 years ago.
• A couple 5.5" tall subframes were built and decked in the attic to provide some storage with decent insulation underneath and blown fiberglass was added to approximately 18" deep about 6 years ago.
• There is no cracking or discoloration of the drywall anywhere in the house.
• Thankfully there are no signs of termites.

The windows are older so I am sure they are not perfectly sealed, but there are no cracking issues with the brick around the windows on the first floor. I suspect this is at least partly due to being a couple hours south of you and freezing being a rare occurrence.

I am somewhat concerned that whatever the issue, it is age or material related and other cracks or bulges will start appearing if I just get this one fixed. I have worked with Hardie before, so I am definitely considering completely replacing the stucco as one option.

 

[Rancher Ed]

I am working on getting some quotes for either repairing the cracked and bulging locations or completely re-doing the stucco and will report back. Any other thoughts or ideas I'm all ears.

 

[EddieWalker]

I'd remove the damaged area before committing to anything else. Until it's exposed, all we can do is guess.