An exterior spray foam and stucco application retrofitted a New Mexico Southwest home.
By Juan SagarbarriaIf you’ve been to Albuquerque, New Mexico or merely observed its design by watching shows like “Breaking Bad,” then you know that adobe-style architecture is commonplace in regards to home building. Although adobe homes were traditionally built using bricks made from clay, sand, and water that were dried in the sun, modern versions of Southwest homes consist of wood-frame buildings covered with stucco. Stucco is a distinct feature in homes around the Southwestern regions because it performs well under the signature dry, hot climate. Be that as it may, stucco is not indestructible and can crack over time, so it will require repairs. While these repairs tend to be merely cosmetic and are needed sporadically, sometimes the level of damage can be significant, prompting the homeowner to replace the stucco altogether.
Take the case of an Albuquerque homeowner and a two-story, 5,400 sq. ft. adobe-style house that was completed with wood lintels and decorative wooden poles underneath known as Vigas. The owner had recently had a spray foam roof installed to his home, and now turned to the next makeover: The home’s stucco exterior. The stucco was in bad shape; it was riddled with cracks that were causing water infiltration. Having witnessed the vast improvement in energy efficiency and indoor climate sustained by the SPF on his roof, he was delighted to hear that he could upgrade the rest of his building envelope with continuous insulation while maintaining his stucco exterior using SPF. This was accomplished via a methodical approach that New Millennium, Inc. (NMI), the local spray foam contractor who installed the home’s spray foam roof, developed by applying a layer of closed-cell spray foam to the existing stucco from the exterior of the home to create a robust, better insulated building while preserving the unique Southwestern façade.
“We like to refer it as our second-generation wall system,” says Rodney Rael, owner of NMI. “We are continuously improving it; we are one of the few contractors in the Southwest that install spray foam and stucco to the exterior of homes.”
The majority of the project consisted of installing a four-part system to the exterior of the home: A layer of SPF, followed by a layer of acrylic coating, followed by a primer coat, and finally the application of synthetic stucco to complete the system. NMI utilized foam and coating products manufactured by SWD Urethane prior to the application of the stucco.
Before any foam was installed, the exterior of the home was remediated and cleaned. This remediation included a removal of all the damaged stucco sections of the home followed by a thorough pressure wash of the entire exterior. The three-man NMI crew then installed plastic sheeting an inch away from the bottom of the wall, masking all the windows, doors, exposed beams, concrete walkways, and patio areas of the home. They installed red stucco tape, carefully placing it in a straight line in areas above the concrete where foam would be applied, such as the patio. The crew also removed all lighting and exterior outlets from the walls of the home prior to the application. Since this was a two-story home, the crew completed the bottom part first and then built scaffolding with fall protection railings to safely and efficiently apply foam to the upper level of the home.
With everything ready to go, the NMI crew suited up in Tyvek coveralls, organic fresh-air respirators, gloves, goggles, and steel-toed boots and began the application of one inch of SWD’s Quik-Shield 112, 2.5 lb. closed-cell spray foam to the exterior of the home. The lead spray technician used a FoamCat 400 proportioner and a Graco CS Gun. The foam was carefully installed to create a smooth surface that would allow the stucco to be trowelled directly over the foam, eliminating the need for wire mesh, which is normally used. Subsequently, all holes and voids in the surface were filled with foam and sanded level with the wall surface.
“Closed-cell foams adds structural strength to the exterior of the home and since the home already has a spray foam roof, this ties the wall in up and around the parapet walls, creating a completely seamless building envelope,” notes Rael.
Prior to the application of stucco, the SPF was covered with a 15-mil pass of SWD’s Quik-Shield 1929 F, a flame-retardant acrylic coating. The acrylic coating provided UV protection for the foam. The crew then applied 10 dry mils of SWD’s Quik-Shield 2000, a low-VOC primer coating as a primer for the stucco. The final stage of the project – the stucco application – was done in a 15-mil application of light cream color stucco to the majority of the house. Both stucco systems applied were manufactured by Sto Corp.
In addition to exterior insulation, SPF also played a major role in preserving the aesthetics of the home. Wooden lintels acting as headers above the windows and doors of the exterior of the home not only rendered a unique feature, they provided structural support to the walls of the home. Upon inspection, it was discovered that although the lintels were structurally sound, they had also cracked and rainwater was getting to them. Instead of removing and replacing them, which would have resulted in extensive and costly demolition and reconstruction, NMI established a solution by lightly foaming over the wooden members with a light pass of foam that fluctuated between 0.5 and 0.75 inches. After the foam application, the crew coated the lintels with a dark, cocoa-colored stucco in order to maintain and accentuate the aesthetics of the home while effectively sealing the lintels against leaks.
“The lintels and headers weren’t rotted, just cracked,” recounts Rael. “By foaming them, we could effectively seal them, but we wanted to maintain the beautiful dark wood color that contrasted with rest of the home, which was a very light cream color. We accomplished that by applying dark-colored stucco over the foam and it worked. It’s hard to believe that those wood members are actually covered by foam.”
Further detail work imparted by the NMI team included the removal of the latillas – a.k.a the decorative wooden poles accentuating the home’s balconies – on account of their succumbing to rot via water infiltration, causing harm to the home by and large. However, much to the homeowner’s delight, these decorative elements did not need to be replaced with plywood or the like… spray foam provided yet another way to retain the attractive wooden features of this Southwest home. The NMI crew simply applied foam to completely seal the areas around the latillas, attached small pieces of wood over the foam, and pinned the latillas onto these wooden strips. Rael affirmed that by applying foam to the edges of the lintels and around the latillas, the owner’s water infiltration headaches are at an end.
The SPF and stucco system provided a seamless air barrier and an aesthetically pleasing facelift to the home.
“We could see what the architect intended with the initial design of the home, but unfortunately the way it was constructed wasn’t the best method,” says Rael. “By reengineering the exposed wooden elements of the home, we were able to create a beautiful and long-lasting home.”
One month and 2,800 pounds of foam – approximately three sets – later, the application was completed and the adobe home’s building envelope was sealed with a monolithic, continuous air and moisture barrier and the aesthetic details of the home were further accentuated.
“I think the most important aspect of this project is that we were able to provide a crack-free system with the foam and stucco system we have developed,” says Rael. “It never ceases to amaze me how you can use spray foam to obtain such a beautiful finish and energy efficiency capabilities at the same time.”
PHOTOS COURTESY of SWD Urethane