DIY Fiberglass Stucco Mix

Stucco is a kind of exterior plaster made with concrete.

Stucco is a kind of plaster used on building exteriors. Instead of the gypsum or lime used in most interior plasters, stucco is made with cement. Concrete stuccos are usually mixed with an acrylic bonding agent that makes the surface more flexible and waterproof than a mixture of cement sand and water is alone. Some stucco basecoats are further reinforced with plastic or fiberglass fibers. Several companies, including cement manufacturer Quikrete, sell pre-mixed bags of the dry ingredients to make fiberglass reinforced stucco.

Things You'll Need

• Five-gallon bucket
• Water
• 4.5-cubic-foot cement mixer
• Shovel
• 3 cubic feet or 36 shovels of coarse sand
• Particle filter mask
• 94-pound bag Portland Cement
• Gallon of bonding add mix
• Pound of 1/2-inch chopped fiberglass strands
• Plastic cup
• Steel plastering trowel

Instructions

1. Add one 5-gallon bucket of water to a 4.5-cubic-foot cement mixer. Add 18 shovels or about 1 1/2 cubic feet of coarse sand to the mixer. Start the mixer.

2. Cover your mouth and nose with a particle filter mask, to avoid inhaling the dust. Add one 94-pound bag of Portland cement to the mixer.

3. Add 1 gallon of bonding and then mix in 1 pound of 1/2-inch chopped fiberglass strands to the mixer.

4. Pour 1/2 bucket or 2 1/2 gallons of water to the mixer. Add 12 more shovels of course sand and mix for five minutes.

5. Stop the mixer. Remove one plastic cup full of the stucco mix from the mixer. Restart the mixer.

6. Pour the stucco mix in the cup onto a vertical steel plastering trowel and begin to turn the trowel to one side. The stucco is too wet if the stucco slides off the trowel before the trowel reaches a 40-degree angle.

7. Add additional sand as needed using a shovel.

References

• Hedberg Landscape and Masonry Supplies; "Stucco Product Calculator"; 2010
• Eager Polymers; "Chopped Strand Fiberglass"; 2006
• Minnesota Lath and Plaster Bureau; "Suggested Guide Specification"; August 2009
• Mortar Sprayer; "How to Stucco"; 2011
• TK Products; "Tri-Mix Cementitious Concrete Surfacer"; July 2000