Q: There are so many reports of problems with synthetic stucco, yet there are so many companies still selling this product.

Is this problem with the product only when installed over a framed house causing moisture build-up versus installation over a concrete ICF insulated block house where there is no place for moisture build-up?

We are building new homes with ICF blocks and concrete and have had a good experience with them in the past. However, we have never used this synthetic stucco material for siding and I am not looking to use any products with problems.

Please give me any feedback you can.

A: In general, synthetic stucco, also known as EIFS (exterior insulation finishing system), is a polymer-based product. It’s a form of plastic that is essentially installed over specially designed board that goes over plywood or concrete bricks.

When I last reported on this issue, the basic problem with synthetic stucco was that moisture would get in through cracks in the exterior, either because the material would crack over time or because it was installed improperly.

Because synthetic stucco is a plastic, it traps the moisture between the exterior and the plywood, or even to the studs themselves. Eventually, mold would form and the house would basically rot from the inside out.

Homeowners living in states where it is hot and humid have had the biggest problems with synthetic stucco over time. However, there appear to have been fewer problems with synthetic stucco that is installed over concrete block, and it has been used successfully in commercial buildings.

The issue for you to determine is whether installing synthetic stucco over insulated concrete blocks would cause a problem for the homes you’re building

Some insulated concrete block home manufactures indicated that either a traditional stucco or synthetic stucco may be applied over the blocks. Because of the negative public perception about synthetic stucco products, you might want to be careful before choosing to use this product.

Before you decide on any one product (there are several synthetic stucco manufacturers), I’d check it out thoroughly. Look for any manufacturers’ reports on the product and then use the Internet to search out whether problems have been reported. A recent search on Google found 86,500 website links for “synthetic stucco,” including several law firms that claim to specialize in product liability lawsuits.

But if you’re not looking for problems in construction, you may want to consider other exterior finishes.

Published: Apr 3, 2008