A Case Study: Applying Synthetic Stucco & Spray Foam in Mid Winter
A Massachusetts foam and stucco contractor pulled off a very challenging project in the cold of winter. Foam and stucco are two materials that have difficulty curing properly in very cold conditions. The article describes waterproofing and performance advantages of having stucco over foam. The contractor's methods for planing the foam into a smooth surface is described in fairly good detail (but not enough detail to go out and do it yourself).
Picture: Mike Belleau his crew applied spray foam, which they smoothed down and coated in preparation for an exterrior synthetic stucco job. This cold, northern, ocean front property (Massachusetts) posed some unique environmental challenges.
A house rebuilding project in Marblehead, Massachusetts required a mixture of unique materials. The exterior required a layer of sprayed polyurethane closed cell foam insulation, on top of which synthetic stucco would be applied. Spray Foam Stucco, Inc., founded by Mike Belleau, uses patented methods of planing (smoothing) the foam, then attaching stucco.
Stucco Has Moisture Intrusion Problems
The benefit of such a system is that stucco tends to have moisture intrusion problems, and this particular home was near the ocean, which caused the original stucco work to deteriorate prematurely. The moisture intrusion caused internal damage as well, causing the insulation method to fail. The original work was torn off and Spray Foam Stucco, Inc. was called in by the general contractor to correct this difficult problem. The original, traditional stucco job had failed, so in order to prevent the past from repeating itself, the general contractor hired Spray Foam Stucco, Inc to create a permanent solution.Below: Surprisingly, the end result is perfectly smooth, and there is no evidence of the underlying spray foam insulation. Closed cell spray foam insulation is an ideal insulator, due to high R-values, and prevention of moisture and vapor movement.
Normally Impossible Conditions Require Innovative Methods
Spray Foam Stucco, Inc. uses unique application techniques and methods to complete spray foam insulation-stucco projects in the dead of winter. Contractors familiar with polyurethane spray foam are aware that getting a successful foam application in cold, humid conditions is unusually difficult and problematic. However, the Spray Foam Stucco, Inc. team has developed some unique methods and innovations which allow them to continue their work, despite these difficulties, even in cold and humid conditions. This job would prove to be exceptionally difficult due to the highly humid oceanfront location, but also due to the frigid Massachusetts winter weather.Satisfied Customers
With 60 local projects completed and counting and no advertising except word of mouth (their company name does not even appear on their truck!), Spray Foam Stucco, Inc. appears to be on its way to success. Happy local residents with the combo stucco-polyurethane spray foam insulation homes have been spreading the word about the stucco-foam combination exterior insulation systems. Spray foam provides more than twice the R-value than traditional insulation, and it prevents moisture and air infiltration, due to millions of tiny closed air bubbles that form the structure of the foam. This moisture and vapor resistant insulation provides excellent insulation, while the stucco exterior provides aesthetic beauty.An Unconventional Materials Mix
An initial challenge to overcome was to somehow apply the stucco to a polyurethane foam surface. First consider that spray foam is normally applied as interior insulation, or as an exterior roof product. Applying spray foam to the exterior of a home is unusual and unheard of. Further complicating things, the stucco needs to securely adhere to the spray foam. Normally this type of work is never done. However, Mike Belleau and the Spray Foam Stucco, Inc. team have come up with a patented solution to do this.How Stucco Was Adhered to the Foam
A unique process is used to allow the stucco to be attached to the SPF surface. After the foam is planed, a fiberglass mesh is adhered to the foam using a basecoat. In some areas, more than just spray foam was needed for detail work such as window and door trim areas. Dow extruded styrene board (blue Styrofoam) was cut, and both the Styrofoam and foam surface were scored to allow the basecoat to securely adhere both surfaces. The synthetic stucco was then applied to the base coat and fiberglass mesh.Preparation
The entire renovation project involved 105,000 square feet (sq ft) of work (75k outside and 30k inside). After the general contractor erected walls, the exterior stucco foam work began almost immediately. However, interior work was delayed until plumbers, electricians, and most other sub-contractors were finished.Foam Requires a Rough Surface For Optimal Adhesion
The polyurethane foam requires rough surfaces to adhere to securely. Although foam is self-flashing (self-adhering), it does not work as well on very smooth surfaces. The naked wood and concrete the general contractor left behind required further preparation work. For brand new wood structures Oriented Strand Board (OSB) was attached with the rough side facing out (and the water resistant side facing inward). Spray foam was applied to the rough exterior side of the board which provided a better texture for adherence. On the exterior concrete blocks of the home’s foundation, the team secured rigid panel boards with a cement based adhesive. The panel boards provides a rough exterior surface for the sprayed foam to adhere to securely.Generating A Perfectly Smooth Exterior Foam Surface
As contractors experienced with spray foam know, it is effectively impossible to create a perfectly smooth & flat surface simply when spraying closed cell foam. After spraying the liquid foam, it quickly rises and cures within about one minute. Foam rises to a few thousand times the size of the original liquid, as the air bubbles form, created a surface that magnifies any imperfections underneath it. Spray Foam Stucco, Inc. developed a unique patented process to plane down the foam into a perfectly level surface, ideal for the final exterior coat of synthetic stucco. Perimeter edges are cut down to the specified thickness using standard carpentry tools. However, larger areas, of 5’ x 10’ or 8’ x 10’ are smoothed out using strings as a guide with special combination 2’ vacuum planers that collect the inert foam chip waste and plane at the same time.Fighting the Massachusetts Ocean Front Cold & Humidity
In order to adhere properly (and to avert disaster), polyurethane spray foam must be applied in dry, warm weather. Spraying foam in the dead of a Massachusetts winter provided yet another difficult challenge.During both summer and winter months, small areas were tarped-in with plastic to prevent debris or wind from disturbing the work. During winter times at night walls were heated using kerosene heaters with metal deflectors to prevent them from freezing while curing (acrylics used in this type of work don't cure properly if they freeze--if this happens the work must be torn off and re-done). Most foam was sprayed just slightly above freezing temperatures. In order to get a good smooth application, foam was sprayed into plastic containers (trash bags) to allow the hose to push out the colder foam and fully heat the lines to the proper temperature. Once at the proper temperature the foam cures correctly. After the lines were cleared, walls and concrete within the tarped-in areas were quickly flashed with foam. The Kerosene heaters were also used during foam applications to assure the foam cured at the right temperature.