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How to Patch Stucco

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How to Patch Stucco

This guide is to be used for the purpose of small stucco patches (as in you cannot apply the same concept to tearing off an entire wall.) Stucco patching requires a decent amount of construction knowledge; therefore this article will assume the user will be familiar with the time involved in setting up and performing the work. These directions should be read through thoroughly before starting the patching process to eliminate any errors that may occur.


The instructions for a the stucco patch in this guide will follow these main steps

Chopping- Removing the bad stucco off the affected area
Lathing- Placing the new moisture barrier (tar paper) and metal lath where the patch will be.
Scratch coat- First layer of stucco
Brown coat- second layer of stucco
Floating- process of creating rough surface on brown coat for the finish coat to adhere to.
Finish coat- This layer is primarily for aesthetics and consists of anything from paint to acrylic based finish with aggregate. (This step is NOT included in these instructions).

Chopping Preparation

Before beginning the chopping process, cover any areas around the patch they may be damaged by falling debris or ruined by cement dusk.
This step in the process is very dusty and the person chopping may want to use eye protection, dust mask, gloves.
The tools you will need to gather for this step include a hammer and chisel, or anything else you can used that will knock the stucco off the wall and tear the old lath from the wall.

Important- You must leave some of the old lath intact around the outside edge in the area you will be chopping out. The lath left on the edge will be tied into the new lath going on the area that will be patched.

The purpose of chopping is to remove the damaged stucco and lath from the sheathing of the wall. So just start pounding the stucco with the hammer and chisel to remove the stucco. The stucco should break away fairly easily.

Lathing Preparation

Gather the necessary tools. Aviation snips and snips for cutting the lath. A tape measure for measuring the cuts that needs to be made. A hammer tacker and staples for attaching the double D tar paper to the sheathing. A hammer and nails for attaching the metal lath to the wall.
Gather the necessary materials. Metal lath, double D tar paper, and rubber membrane.
pull back the old metal lath from the non-damaged stucco in the outside of the patch area. This is the lath previously described as important that should not be removed.

After the metal lath from the good stucco has been pulled back and the sheathing is exposed, cut a piece of the double d tar paper to size and use the hammer tacker to stick the piece on the sheathing.
Seal the outside edge behind the exposed metal lath off using the rubber membrane. The rubber membrane may not stick well to the area being seal off. In that case, tack a few staples in or improvise in order to keep it in place.
Cut a piece of metal lath to size to fit into the patch area. The metal lath should be large enough to fit beyond where the metal lath from the good stucco on the outside edge can fit over the cut piece.

Place the lath over the double d tar paper in the patch area and nail the lath in just to stay in place.
Proper nailing for the patch will include nailing into any part of the sheathing that will provide a sold anchor point. Don't worry about hitting studs because it is only a patch. The nails should be spaced about 6 inches apart.
Nail the lath from the good stucco on the outside edge of the lath over the lath you set in place. Nail all around the lath to ensure the overlapping lath is nailed flat down.

Scratch Coat Preparation

Properly cover the area around the patch where anything may get dirty.

Mix cement

Gather necessary tools. Hawk, trowel, scoop, scratcher, bucket with water (not necessary, but nice for putting dirty tools in and washing after), wash brush, and a margin trowel or pointed trowel (for sticking mud into tight places).
Gather the necessary materials, the mixed cement.

The hawk and trowel work similar to an artist's brush and board the holds the paint. The hawk holds the cement; the trowel is used to spread the cement.
Use the scoop to place some cement on your hawk. Use your trowel to take the cement off the hawk and spread it onto the wall. Notice that the purpose of the scratch coat is not to even out the wall with a coat of cement. The purpose is to skim the lath and create a layer for the brown coat to stick to. Skim just enough cement over the lath so that it is overed.
Use the scratcher to scratch the entire skimmed area.
The cement will most likely be too dried out to use for the brown coat. Dispose of the old cement and prepare to mix a new batch for the brown coat.
Clean your tools so they don't get ruined. Use a wash brush and bucket of water, or whatever else that may work.
Wait for the scratch coat to dry before putting on the brown coat. You will know the patch is dry when it turns from a dark grey to a ligh grey.

Brown Coat

Notice Right after the brown coat is finished you will have to start the floating process


Ensure that any area that may get dirty around the patch is still adequately covered.
Mix cement
Gather necessary tools. The darbie or 2x piece of wood is used for scraping the excess cement off wall and leveling it, Hawk, trowel, scoop.
Gather the necessary materials, the mixed cement.


Scoop cement out of the bucket and place in the hawk. Use the trowel to spread the cement onto the wall. The brown coat must be level with the surrounding wall of the patch, so use enough mud to fill the patch in adequately.
When the patch has been filled in with cement, use the darbie and scrape down across the patch area. Wetting the darbie makes the process work better.
If any holes exist after running the darbie across the patch, throw some cement in the holes and repeat the leveling process.
Repeat this process until the wall is flat with no large holes and the patch is level with the rest of the wall.
Floating is the last step in the patching process. Notice the wall should be as level as possible from using the darbie. The purpose of the darbie was to level the wall, now the purpose of floating will be to create a rough texture on the brown coat for the finish to ashere to. Make sure to start the floating process right after the brown coat is finished so that the cement on the wall is still moist. The wall should be moist to the touch and feel spongy when pushed on.

Gather the necessary tools, which include a float and a bucket with about the 1/3 pale of water.

Again, the purpose of floating is to create a rough surface for the finish to adhere to. This is identical to sanding a piece of wood. Instead of using sand paper, you use a float. Instead of wood, there is cement.
The float must be wet for this process. Submerge the float in the pale of water and shake the float after so it is not soaking wet.
Use a swirling motion with the wet float to start leveling the wall. Be careful not to press too hard against the wall so that you dig into it, but use enough pressure so that you are effectively roughing up the surface of the wall.
Make sure the outside edge of the patch is smoothed out onto the existing wall with the float. You may apply more pressure on the outside of the patch for this purpose.
When the patch is roughed up and evened out with the area previously existing wall around it the job is complete.
Completion- Now that the patch is complete it must cure before putting any type of finish coat on. There is no need to rush putting the finish coat due to the worry of damage; the finish coat is primarily for aesthetics. Typical recommendations for curing are about 30 days.

Mixing Guide
This mixing guide is separate from the flow of the instructions because it will need to be done more than once. Whenever the instructions say to mix cement, reflect back to the mixing guide. The following will assume one full five gallon bucket of cement will be mixed.

Gather the necessary materials needed to make a batch of the cement. These materials include a bag of pre-mixed cement (with fibers), bonding agent, and water.
Gather the necessary tools. A margin trowel for scraping the edges of the bucket. An electric drill and beater for mixing the cement. A wash brush is recommended for cleaning the tools after mixing the cement.
Fill the bucket up about ¼ full with water.
Add roughly 16 ounces of the bonding agent.
Fill the rest of the bucket with the pre-mixed cement.
Mix the bucket with the electric drill and beater until the right consistency is met. You will know the cement is at the right consistency when it is not soupy, but it keeps its form fairly well. You may need to add some water, check the cements consistency.

This guide makes the following assumptions:
Problem area has been identified
The sheathing and studs behind the old stucco are not rotted to the point where they wouldn't make a good anchor point.
The patch in this article will not include the finish coat due to the many variations in textures for stucco finish coats.
Patchwork around windows and doors will need to have flashing and rubber membrane installed. Stucco at the bottom of a wall may require weep screed (unless it is evident there was none there originally).
The person doing the patchwork will need a fair amount of construction knowledge. As in they have done different home projects before or work in construction.

Things You'll Need
Primary tools List

Trowel- primary tool for spreading cement on wall
Hawk- tool used for holding cement mix in one hand while spreading the cement on the wall using the trowel with the other.
Darby or 2x piece of wood- This is used to even the patch out with the rest of the wall.
Margin trowel or pointed trowel- For placing cement in tight areas.
Drill and beater- This is the easiest way to mix the cement. Improvise and you may not need an electrical drill and beater.
Wash brush- For cleaning tools.
Aviation snips- for cutting small pieces of metal lath
Snips- for cutting large pieces of metal lath
Scoop- Used to scoop the cement mix out of the bucket. Improvise to use anything else for the same purpose.
Scratcher- This is used literally to scratch the stucco during the scratch coat. Anything may be used in its place for the same purpose.
Hammer tacker (stapler)- This tool looks similar to a hammer. You load staples into the device and pound on things in order for a stapler to come out.
Tape measure
Chalk or other device that can be used for marking
float (This looks like a trowel with a sponge on the side without the handle)
5 gallon buckets (The more you have the easier the process will be. These will be used for mixing in, holding water, collecting garbage and debris, and hauling around tools.)
Other tools

work clothes (this is a dirty process so don't wear any clothes you plan on wearing out next Friday night)
Dust mask
Eye protection
Work gloves

Metal Lath
Double D tar paper
Dry cement mix (To simplify this guide, assumptions will be made that the user is using a premixed bag of cement made for stucco. These pre-mixed bags will often include the fibers in the mix. I recommend asking someone in the store you are buying the materials from to help you find the right mix.
Rubber membrane- This stuff comes in rolls. One side is a white plastic film and the other side is a sticky black tar like material.
fibers (If you buy a bag of cement with fibers then you do not need to buy additional fibers)
Bonding agent- This is a white liquid that looks just like milk. Ask a person at the place you purchase the materials to ensure you buy the right product.
Water (a hose with a nozzle comes in handy for clean-up)
covering materials (tarps, tape, poly, anything that will cover up an area that could get messy throughout the process)