The existing house was clad with traditional three-coat stucco. We were tasked with trying to match its finish not only on the new sunroom, but on all of the dormers as well—this included the three new ones we built and the four existing dormers that had water damage and needed new flashing and cladding. During pre-construction meetings, I discussed cladding alternatives with our stucco subcontractor. Initially, we were going to go with EIFS, but we were concerned about having to deal with a thicker wall assembly. The EIFS would have helped with any thermal conductivity issues related to the wall assembly, but because there was such a small amount of wall area (compared with the glazing), we decided to go with a modified system of two-coat synthetic stucco (made by Total Wall) with fiberglass mesh embedded in the base coat. It would be applied over 1/2-inch Durock cement board, which would be installed over 1/4-inch Keene DriWall drainage matrix membrane.
The Keene DriWall was fastened to the Zip wall with 3/8-inch staples, while the cement board was fastened to the sheathing with 1 1/2-inch-long Durock screws. To protect the exposed ends of the Durock, the stucco subs installed metal J-flashing along the bottom edge of the walls, as well as around all window and door perimeters. They “taped” the Durock seams with fiberglass mesh.
Starting with the dormers, the stucco subs applied a 1/16-inch-thick butter coat of Total Wall T-2000 Base Coat over the Durock…
…then quickly embedded pre-cut lengths of Total Wall reinforcing mesh. The stucco subs worked the mesh into the butter coat starting at the center and troweling toward the edges, overlapping runs of mesh by a minimum of 2 1/2 inches. Then they applied additional T-2000 Base Coat mix, thick enough to embed the mesh so that its pattern wasn’t easily visible. After a day or so, the crew installed backer rod and sealant around the dormer windows and applied the finish coat.
Using a plastic float, the stucco subs troweled on a thin coat of Total Wall’s Total Premium Elastomeric Finish over the surface, providing a medium sand-blast texture. The finish coat was tinted, so no further finishing was required.
Where the new sunroom abutted the existing wall, the stucco subs rolled Total Wall’s Stucco Bond liquid bonding agent onto the existing three-coat, then covered the seam with fiberglass mesh. Next, they applied the T-2000 Base Coat mix, feathering it onto the existing stucco surface.
With the base coat on and the sunroom’s windows and doors caulked, the stucco subs applied the finish coat.
The stucco on the existing house was power-washed with a bleach solution, then a bonding agent was rolled on to the surface. We had to rent a boom lift for a few of the higher work areas.