The word “insulation” typically brings to mind lofty batts of spun fiberglass, rigid foam panels and blown-in cellulose. For decades, the best way to insulate concrete block was on the interior of the wall, which required framing another wall up against the concrete and insulating between the studs. Today, with the use of Exterior Insulation and Finish Systems (EIFS), you can add R-value to your concrete block wall on the outside. As of 2012, the application of EIFS, which gives the wall a stuccolike look, is only available through certified EIFS contractors.
Consult your local building authority before having EIFS applied to the exterior of your house or building. Most local codes require a building permit before changing the dimensions of an exterior structure, and the application of EIFS will add about 3 inches to the exterior of the wall. If the existing wall has cracks or loose blocks, make repairs before installing EIFS.
The contractor applies a layer of adhesive over the surface of the concrete blocks and then installs a vapor barrier and high-density rigid foam board insulation on top of that. The next layer of steel grid or mesh attaches with mechanical fasteners, drilled into the concrete blocks. A semisolid base coat, containing expanded polystyrene (EPS) goes next, followed by a topcoat. You can choose a topcoat color or customize it by adding aggregate.
Expansion joints might be necessary to control future wall movement. The number and placement of these joints varies, but typically they’re positioned over existing expansion joints in the concrete block wall, in large fields of EIFS, and where the EIFS abuts other types of exterior cladding, such as brick or stone. The expansion joints run from the surface of the cladding all the way to the concrete wall, so they must be sealed to prevent moisture from entering the joints.
Like other types of siding, EIFS should not come into contact with the soil. Local codes determine the minimum distance between soil level and the bottom of the EIFS, which is generally around 6 inches. One of the downsides to EIFS is the inability to patch cracks or spalling without having to reinstall the base and topcoat from wall to wall. This makes it inadvisable to install the system over concrete block wall that cracks frequently, due to soil or foundation settling or movement.