How bad is the situation, and what do you want to achieve?
The house was recently put on the market and the chimney had a beautiful paint job applied to the entire exterior. I had seen this sort of thing several times in the past, and started looking for the red flags; I found them. I pulled out my knife and started digging. The joints had about 2 millimeters of hardness on the outside, then my blade hit the powder behind the hardness. The paint covered up the loose mortar joints. The paint was an act of camouflage. The inspector (for the sale of the house) did not catch it. We got called out by the new owner because she wanted a new rain cap put on the chimney. She watched me put my knife into the soft mortar joints.
Stucco can be used for camouflage as well.
I have pulled failing stucco off of chimneys that had crumbling brick and powdered mortar behind the stucco; the stucco was acting as a big chimney cast and was holding it together.
There are various reasons why someone may not want us to use expanded metal, to stucco the entire chimney, etc. And many of these reasons make sense and save money and time. Usually we will accommodate and do the repair. In rare instances we will not do the repair. We turn down repair work when we feel that it will not be adding value, which is a waste of time and money.
Expanded Metal For Reinforcement
Just like rebar placed in a concrete form before the concrete is poured, you can install sheets of expanded metal on the chimney before you apply the stucco. This strengthens the stucco tremendously! It also extends the life of the repair exponentially. The sheets of expanded metal are installed with masonry anchors designed specifically for the installation.
Two Coats of Stucco mix are applied.
The stucco mix we use at Rooftop Chimney is a pre-mixed, engineered product that we purchase at Masons Supply Company. It has small nylon fibers mixed into it that act as reinforcement.
The first coat applied is a “scratch” coat, which is applied with a notched trowel. The notches leave grooves in the finish. This is standard procedure for a strong bonding of multiple coats of stucco.
The Finish Coat
A final smooth “finish” coating is applied. A different engineered mixture is used for this coating. Stucco needs to be protected from freeze damage after it is applied. The stucco needs to cure for 30 days before either siloxane waterproofing is applied or masonry paint is applied. We use Sherwin Williams Super Paint exclusively when painting stucco and any other masonry.
Some Final Words…
There are some stucco repairs that are performed because it is better than doing nothing. Sometimes the customer asks us to do stucco work without installing expanded metal due to the economics of the situation. Doing stucco work on a chimney without installing expanded metal can be a repair that lasts decades if the work is maintained with waterproofing or proper painting.
Some stucco repairs, such as patch work cannot accept expanded metal due to matching thicknesses of existing stucco.