How to do stucco exterior wall 5 steps

How to do stucco exterior wall 5 steps

Stucco is very popular for siding houses and even businesses depending on the area you live in. To apply the cement stucco base, you should know that there are three layers for the base coat: scratch coat, brown coat, and finishing coat. Applied in that order.

Before I explain, I want to clarify that how hard it is to do stucco depends greatly on your skill set. For those who have never touched a trowel or mixed stucco, you might find out that getting the desired result is not possible by yourself.

For that reason, before buying enough stucco for your whole house – buy a bag or 2 so you can test it out. Most companies that provide these services have a pallet or two of old bags lying around from past projects so asking them for cheap leftovers might work out as well.

I don’t want to put anyone down, I want to raise people up to do more stuff by themselves. But buying materials for a house is a heavy investment, I encourage you to start small and grow the project when more skill is present.

Please be sure to follow the instructions below to apply all three layers correctly.

Materials needed for the basic stucco wall project

The good thing for stucco hobbyists is that they don’t need many materials to start out. The materials are reasonably cheap if you use the most basic stuff. I would not buy the expensive stuff, before I’m comfortable I can use them as intended.

  • Building paper for walls not made of concrete or bricks (wood, etc.)
  • Metal meshing
  • Weep screed for the bottom of the wall
  • Control joints
  • Galvanized nails
  • Mixing barrel
  • Trowel with notches for scratch coat and long trowel for base coat
  • Finishing trowel for finishing coat and float for texture if used
  • Cement, lime, sand, and water (these are the ingredients for the base coat)
How to do exterior stucco begins with preparing the work

How to do stucco on a house simplified

I’m going to break this guide into 5 steps. Hopefully, one that is easy to understand.

Step 1: First you need to make sure to prepare your walls.

Every proper construction project begins with preparation. You will want to ensure your walls are clean and clear of debris.

Concrete walls can be power washed, and brick walls must be careful not to wash them too hard as high-pressure power washers can go through the surface layer/joints and cause water damage.

This warning comes from experience.

If your wall is not made of bricks or concrete you want to put building/waterproof paper on it so that the edges cover at least 4 inches of the other paper. This way it’s unlikely water can get through the surface, into the wooden wall.

Stucco reinforcement is usually a little like metal wire lath like in this picture. It can have unique clips for screw attachment etc.

You will want to apply metal reinforcing on top of the paper before you try applying any stucco. This will help ensure the stucco bonds better to the wall.

Install weep screed on the bottom of the wall and install the metal reinforcing on top of that. Make sure it runs the whole wall length horizontally with your tool of choice (laser is easy to get these days).

You can check if it’s bullet straight from to side or does it make “waves” if your wall is not straight. You can make little fixes now.

How to stucco a concrete wall is pretty much the same process as brick and board walls. If you have brick or concrete walls, you can skip the metal reinforcing if you like, but I’d still do it.

If for some reason the stucco won’t adhere well, the metal will keep it in place for years. Also with high spots, it offers us protection from falling pieces.

I’ve probably fixed nearly 100 walls and thousands of holes in the stucco where there was no metal reinforcement and it usually starts with one patch falling and water eating the surface around the hole in the stucco. If you patch it, it will usually pop out or crack as it’s different strength from the surrounding material.

So the metal reinforcement can save you some time if there comes time for repairs.

Note: Poured concrete walls need to be ground, sand-washed, or acid-washed so that the stucco will adhere well. That is another common reason why stucco cracks and needs to be repaired before its time.

Step 2: After reinforcement, its time to do control the joints

Now if you need to install reinforcement of any kind, make sure that the metal is galvanized (rust-resistant). The installation of reinforcement materials will help the stucco get a better bond like stated before and helps strengthen the structure. The weep screed is there to let the water escape so install it well.

If you use control joints, they are meant for dividing the wall and crack control. Try to place them as square as possible and aesthetically so your wall won’t look mismatched. Also, place them where two different walls meet as that is the usual cracking point.

Other than that, you can use them to level the wall if it’s not consistent or uneven. Just need to install them all with a ground wire or something else like that. You set the wire horizontally from side to side or vertically and check nothing pushes it forward and everything is level with it.

Now there is one important thing to remember, depending on the type of reinforcement. If it’s galvanized net, the stucco needs to get behind it a little so it will stick to it and the wall behind it. Also, follow the reinforcement nets installing instructions so you have it attached well to the wall and one attachment point doesn’t have to carry too much weight.

Ideally, the net won’t be carrying the stucco, but if it with time has to, all of it won’t come down.

Step 3: When everything is ready, its time to apply scratch coat

Mix one part cement, ¼ part lime, and three to five parts sand for the scratch coat. Mixtures change from place to place and you should be able to get ready mixed bags as well. Add enough water to make this a workable mixture, keeping in mind that you will apply this coat in a ½ inch layer.

If you have a ready-mix bag, remember to check the manufacturer’s instructions for the correct amount of water and how long it’s workable. Do not add more water to it after mixing as it will make it weaker than the rest.

Before applying you will want to dampen the wall with a spray of water to help this layer bond better. Don’t soak it, just let a nice spray so the bricks or concrete is moist, but won’t be dripping wet.

This should completely cover the metal reinforcement material. While applying this layer, be sure to use your notched trowel to leave horizontal lines on the surface. The grooves will help the brown coat bond more successfully. Allow your scratch coat to dry for several hours.

Alternatively, if you’re using a hopper gun for spraying stucco, you can leave it on the spray surface. It is rough enough for the next layer to adhere to. This is how I usually do it if I have big surfaces.

Step 4: Next we have to do the brown coat

After the scratch coat is dry after 24 to 48 hours, you will make the same mixture as in the step above for your brown coat.

Be sure to dampen the scratch coat before applying the next layer for better adherence and stronger cement curing. Now with the brown coat, you need to ensure that it is being evenly troweled on to 3/8 of an inch thick and smooth.

Depending on the wall, how level it is, and are you using control joints, you might have to do this twice to get a level surface.

Without control joints, I usually do one layer horizontally, using a long screed or long finishing trowel (24 inches at least) to finish the surface.

I let the first layer dry and sand the high trowel marks away. Then I’ll do the second coat that I finish vertically. This way brown coats will be level and there will be little “waves” on the surface as it’s done like a cross.

The first layer is straight up, and the second layer is to the side after it’s hard.

Another way is to do “benches” and let them dry or make them with plywood and fill the middle with stucco. It doesn’t have to be this complicated, but I’ve met some walls during my career that had to be done the hard way. Usually old brick walls.

Step 5: How to do stucco finish

Once your cement base coat layers are done, you are ready to apply your finish coat. Just remember that before you can do the finish coat, you must allow several days of drying time for the base layers and moisture them daily.

You don’t want to pour them with water, gently spray so the surface will get moisture. This will help the curing process of cement.

When you’re doing the finishing layer, you can do it with a hopper gun to get the texture or finish with a trowel and float. It’s a matter of taste here. If you’re using a hopper gun the stucco structure has to be consistent from start to finish.

If not, it will look like multiple different guys did it. It’s also important to spray it from side to side or do small circles or other techniques to make it look perfect everywhere. This is something that is learned by doing.

If the stucco is too moist or dry, it will not look good. It has to be perfect for a sharp texture finish.

Trowel and wooden float might actually be a little easier for beginners. You make circles with the float and it will make the surface look smooth. Still, the stucco needs to be just right so it will not only roll with the float. This too is best learned by doing.

That said, a hopper gun will probably be the easiest as it is sprayed and let dry. When you spread it with a trowel and float, you might need a little skill depending on the float. Some ready-made finishing coats are easy to apply with plastic float and the layer is very thin and might need a paint coat below it.

Conclusion

I hope this answered how to make a stucco exterior wall. It can be a little bit confusing and sometimes better left to professionals. On the other hand, if you have manageable wall sizes it isn’t that hard and can even be fun to do yourself.

I do think it’s not a job for everyone, but some people like me genuinely enjoy the process. When you end up with the perfect wall it yields great satisfaction.

Working with stucco is all about preparation. You have to have your wall ready for doing the coats and no interruptions. Have the stucco materials and water near so you won’t have to run around to get them. When you can make stucco and apply it to the wall, it will be easy.

Here is a guide on installing Hardie boards as an alternative to stucco and here is a guide on how to cut the cement boards.