What to Consider When Bolting Concrete Stucco
Concrete stucco is an extremely hard surface so bolting concrete stucco you must use the right fastener to assure that it stays secured. There are several methods of bolting concrete and each has its own fastener. You can screw, nail, or drive an anchor into concrete stucco.
Types of Stucco
You should first find out what kind of stucco you have. Traditional stucco is made of sand, Portland cement, and lime. It dries as hard a stone. There is synthetic stucco called Exterior Insulation Finishing (EIFS). This product is made of acrylic applied over foam insulation. EIFS may require special bolting fasteners as it is not as durable as stucco.
You should know the weight of the object that you are bolting to the concrete stucco. This is called the load. You want to choose a bolt that is rated for that weight. The general rule of thumb is that the load rating should be four times the actual weight of what you are securing to the stucco.
Concrete screws are fast and easy to use. Concrete screws are installed by drilling a pilot hole with a carbide bit. The bit comes in the box of screws. The screw that is inserted is made of hardened materials and has high and low threads made to go into masonry. There is no need to insert an anchor into the hole except in heavy duty applications. A concrete screw can be removed if necessary.
There are many types of concrete anchors. Epoxy anchors are installed by drilling a pilot hole and then inserting the bolt. Epoxy is inserted with the bolt and then the epoxy dries securing the fastener. They are good for close spaces or using at the edge of a surface. A similar anchor is a grouted anchor. These are installed in the same way as an epoxy anchor but they use a special grout to secure the bolt. A drop-in anchor is an expansion shield and expander plug in one unit. A hole is drilled in the surface and then the unit is tapped in. When the screw is turned it expands to fill the hole. A wedge anchor is a similar idea. The hole is drilled and a wedge is inserted then the screw is put in a turned. As the screw goes in it wedges up against the insert to hold the screw in place.
A concrete, or masonry, nail has special spiral or ringed threads that hold it in the masonry. It can be installed with a manual hammer but a hammer drill is less likely to damage the stucco. Be sure to use a masonry bit. There are also nails that you install with a powder-actuated gun but these require a special tool and special nails so it is only practical if you are going to do a big project.
When you are bolting concrete the number one concern is not to harm the stucco surface. Be sure to use the proper tools and fasteners and consider whether you will want to remove them in the future.