How To Patch Badly Cracked Stucco

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The stucco on the exterior of our house is badly cracked. It was like that when we bought the place, and I’ve been told it’s not unusual for stucco to crack. But I would like to fix ours if possible.

I have been reading online about how to repair cracked stucco, and there seems to be a lot of disagreement about the best way to do it. Some people say you just need some drywall mud and a putty knife, while others suggest using a wire brush to remove any loose stucco first, or getting some premixed goop which they sell at Home Depot.

Any advice?

Stucco mix is a mixture of sand, Portland cement and lime. The correct ratio of these materials will vary, depending upon the size of the job. To repair cracks in stucco, you will need to make a new batch of stucco mix.

To make your own stucco patching material, use one part Portland cement to three parts sand, along with a little bit of lime or mason’s hydrated lime. You may also add some acrylic fortifier. For smaller jobs, it is not necessary to add lime or acrylic fortifier, which can be purchased at most home improvement stores.

Make enough for the job at hand to avoid wasting any unused materials. Stored in an air tight plastic bag or bucket, extra stucco mix will stay good for up to two weeks or so.

The quality of your patch job will depend heavily on the preparation work you do before applying the actual stucco patching material.

Prepare the area where you are going to apply the patch by using a chisel and hammer to chip away all the loose material from around the crack you are repairing. Once all of the loose material has been removed, use your garden hose or pressure washer to wash away all debris that has

There are many methods to patch stucco and I’ve provided a detailed tutorial on how to patch stucco with a scratch coat.

This is the method generally used by professionals and the method that most closely resembles the material and technique used in original stucco installation.

Unfortunately, it’s a lot of work and the cost of materials can be high.

If your house has minimal cracks ( 1/16″ or less) and you want to try something simple, easy and inexpensive this may be a good option.

The first step is to clean out all of the loose material in and around the crack using a wire brush or putty knife.

Next, get some elastomeric caulk (my favorite is Sashco Through The Roof) and squeeze it into the crack along its entire length.

Don’t worry about how neat it looks, you’re just trying to fill the crack completely.

Let it cure for at least 24 hours before proceeding (longer if possible).

Stucco repair is best accomplished using the same materials and methods used in the original construction of your home. A stucco application consists of a base material (usually expanded metal lath), a scratch coat, a brown coat, and several layers of finish coats.

The base material for most modern stucco jobs is usually expanded metal lath or wire mesh that’s nailed to the sheathing (plywood or OSB) behind the exterior siding. Stucco cement is then applied over this base in three to five layers. The first two layers are called the scratch coat and the brown coat. These two layers are made from a mixture of Portland cement, hydrated lime, clean washed sand and water. They are applied one after another, with the second layer being scratched when it’s about half dry so that it will bond to the third layer. The third layer is made from Portland cement and lime only, commonly called a “one-coat stucco.” It’s finished off with three or more decorative coats of thin acrylic color coats that are sprayed on using an airless sprayer.

In order to repair badly cracked stucco you have to match your existing materials as closely as possible, including type of cement, sand and lime used in

An early step in repairing stucco is to remove damaged stucco and clean the surface. This means that you will need some type of masonry blade to cut away damaged stucco to a good solid base. It is important to cut away damaged stucco about two inches beyond the actual damage on each side. Remember this is the area that you will have to fill in so it needs to be sound.

Any time you are working with tools make sure that you are wearing safety glasses and gloves, as well as any other protective gear necessary. You also want to wear a mask when cutting through stucco because of the dust that will be generated by the work.

Once your surface is prepared you want to prime the area. It is important that you use a bonding primer like XIM 400xt or S-1 Bonding Agent. The primer can be applied with a roller or brush depending on how large your patch area is. If it is larger than 50 square feet you may want to consider using an airless sprayer which will help ensure an even coat and minimize waste since virtually no overspray occurs with this method.

Once your primer has dried (approximately one hour) apply your first layer of Stucco Patch, also known as

Stucco patch can be used as a re-surfacing material as well as a patching material for repairing small and large cracks. TIP: If the crack is larger than an eight of an inch, use a stucco wire mesh in the mix to help prevent future cracking.

You will need to get the proper stucco mix for your exterior. You can buy this from most home improvement stores, or look online for tips on how to make your own stucco mix. The mix should be a combination of sand, cement, lime and water.

Stucco Mix ingredients:

1 part Portland cement

3 parts sand (no larger than 1/8 inch)

3 parts hydrated lime (not agricultural lime)

1/2 to 3/4 part water

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