Cement Stucco Foundation Finish
Summary: If your bare concrete or concrete block foundation is exposed, you can use stucco to cover it up. You can add permanent colors to stucco and create very interesting textures with little effort. Be sure to clean the surface; applying stucco should be done in slightly warm weather.
DEAR TIM: My home has two types of foundation: concrete block and poured concrete. They look horrible because of the different colors and textures. How can I make them look uniform? I have seen other homes where the foundations have been covered with a stucco material. Is it too late to do this? How was the stucco successfully applied to my neighbors' foundations? Lori B., Bright, IN
DEAR LORI: I couldn't agree more with you with respect to the contrasting colors and textures of concrete block vs. poured concrete. There is simply something about the horizontal and vertical lines in the concrete block that clashes with the monolithic appearance of poured concrete. Making the two different foundations appear as if they are one is going to be fairly easy. Masonry walls have been stuccoed for thousands of years and some still retain their stucco.
The first thing you need to do is clean the foundation surfaces. This is one of the few instances where I advocate the use of a pressure washer. Often rainfall causes dirt and silt to splash up onto a foundation. If you live in an area with clay soil, very fine clay silts can get deeply embedded in the pores of both the poured concrete and especially the concrete block. Pressure washers quickly and efficiently remove this silt.
Squirting the dirty masonry with a regular garden hose and a nozzle will not remove all of the dirt. A stiff scrub brush with soap will work, but that method involves considerable work. Once you have cleaned the walls, rinse them with clear water making sure they are perfectly clean.
Next I suggest you buy one or two pieces of one-half inch thick cement board. It typically comes with one side slightly rough and one side smooth. Tack this cement board with the rough side facing out to an existing wall surface so that it does not flex. If you have to build a small temporary wood stud wall, do so. This surface is going to be your stucco simulator practice area.
Mixing stucco is easy. I suggest you blend three parts medium sand, one part Portland cement, and one-half part hydrated lime. Mix the dry or damp sand with the cement and lime until you have a uniform color and texture. It is now time to slowly add clean water to the mix. Blend the water, sand, cement and lime until the final texture and consistency resembles bricklaying mortar. When the correct amount of water is added, the stucco mix can be formed into a ball that is fairly plastic and will hold its shape if set on a flat surface.
The stucco thickness should not exceed one-quarter inch. Use a regular steel trowel to apply it with curved strokes. The stucco should magically stick to the cement board without falling off. If it does fall off, the stucco mixture may be too dry. The hydrated lime in the mix makes the stucco sticky and improves the workability of it.
Now comes the fun part. There are an infinite number of designs, techniques, tools and textures you can create. For example, you can use a stiff brush and stipple the stucco. You draw a brush across the stucco to create random brushed texture. The steel trowel can be dabbed randomly into the stucco to create a different texture. Small angular colored stones can be cast into the wet stucco. The only thing holding you back is your imagination.
Be sure to stand back 20 or 30 feet to look at the practice stucco simulation. This is what people will see from the road or your yard. Looking at the stucco up close will give you a false impression of the real look you will see once the job is complete.
The best time to install stucco, in my opinion, is cool to slightly warm weather. Working on an overcast day with little or no threat of rain is best. Sunny, hot and breezy days are the worst as the stucco can dry too quickly. You want the stucco to dry slowly. Try to follow the sun, meaning work on a wall surface after the sun has moved and is not directly striking the foundation wall
Once the stucco has hardened to the touch, keep it slightly damp with very light misting of water. If possible, try to do this for two to three days. This added water allows the cement in the stucco to cure allowing millions of microscopic crystals to grow into the poured concrete and concrete block surfaces. These crystals are the glue that permanently bond the stucco to the masonry surfaces.
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Comments:
AsktheBuilder 10 Dec 2007, 07:22
Just,
The answer is maybe...... There are several variables that might cause a failure. Be sure the existing is clean and damp before you start.
Jack McG 19 Dec 2007, 08:20
Hi..
I live part time in Nicaragua which is a very poor country. I am construction oriented but not much experience with concrete, stucco or block work. I want to do some volunteer work on my own to help some families build block houses to be able to move out of their bamboo or wood shacks. Can you recommend a good book that would contain all the basics for masonry work and all the formulas for various cement and concret mixes. I also need info for strengthing the walls for protection against earthquakes and tremors. They don't pour foundations there since there is no frost. Work starts right from the tamped ground. Thanks in advance for you help.
AsktheBuilder 19 Dec 2007, 08:24
Jack,
Get the Concrete Masonry Handbook from the Portland Cement Association.
hamik 15 Jan 2008, 19:37
restuccoing vs painting house
hi..... i just purchased a home that has unfinished stucco work,meaning no paint ,is it worth having stucco with dye put on or just have it painted,new stucco work was on the front only ,sides and rear has slight cracks but not to big,heard paint is better cause it "acts like a sealer on house",dont know which way to go any info will help thanks
AsktheBuilder 16 Jan 2008, 14:40
Hamik,
I would never paint stucco. Then it becomes a maintenance issue.
Mike 25 Jan 2008, 20:38
Hi,
Just wonering how I can create the texture in the stucco that is in the picture above, that you say is almost 80 years old, and what tools I need? Thanks, Mike
AsktheBuilder 26 Jan 2008, 07:22
Mike,
I was not even a glimmer in my Dad's eye when that stucco was applied. It looks to me that it was done with a wood float. Remember that the cement paste on the surface has long ago been eroded by weather. You may have to do some accelerated weathering after the stucco has been cured for 90 days. I urge you to make some test panels on cement backer board until you get the technique mastered.
Glenn 08 Feb 2008, 19:54
I have an exterior wall which is stuccoed and I am going to put brick on.
Can I leave the stucco, and fasten wall ties through it, or should I tear
off the stucco. What are the pros and cons?
AsktheBuilder 09 Feb 2008, 07:36
Glenn,
You can leave the stucco if you want, but I would take it off to make sure I had a fantastic water membrane in place, perfect base flashings and the proper reveal around windows and doors. View all comments |



