This post is one part in a series about high-performance window installation:
Masonry wall assemblies are often using VISCONN fluid applied air barrier and WRB to waterproof and airseal the masonry. It’s best to use a fluid applied material for these uneven and porous substrates. The VISCONN can fully coat the uneven substrate and adhere properly to the porous material. VISCONN can be used on the interior and exterior. If it’s only being used on the exterior then the VISCONN turns into the window rough openings to be able to airsealed on the interior side of the window with CONTEGA SOLIDO IQ tape. CONTEGA SOLIDO IQ does not need a primer for adhering to masonry substrates.
Historic masonry and stucco walls are typically relying on the exterior finish facade to act as the waterproofing for the wall. Connecting the window to this finish material with a tape can be difficult to conceal. Trim can conceal the tape connection. Or projects can use CONTEGA SOLIDO IQ tape which has fleece covering designed to hold plaster.
Let’s take a look at some specific masonry wall assemblies and how the window installation can adjust based on the type of masonry wall assembly.
Historic Masonry
Wall assemblies with structural masonry that needs to be left exposed on the exterior typically have historic sills that cannot be disturbed. Historic status or similar landmarks status can limit the amount of work done on the exterior side of the window unit install. Often the masonry of the rough opening is treated with VISCONN and there’s an exterior tape connection from the window frame to the VISCONN at the header and jambs. This tape connection is typically concealed with a brickmould or similar trim finish. The exterior sill connection from the window frame to the exposed stone sill is typically done with a caulk joint. This caulk connection might require maintenance to stay watertight over time. The window unit is air sealed to either VISCONN or the INTELLO PLUS membrane on the interior sides using TESCON PROFIL, PROFECT, or CONTEGA SOLIDO IQ.
Here’s a great video of Ken Levenson talking through a historic masonry window installation.
Reservoir Cladding
Wall assemblies with a back vented brick finish need to allow weeping to the exterior side of the brick at the window headers. The window unit is waterproof taped to the WRB and the metal sill pan is flashed to the exterior side of the brick façade. It’s best to use a WRB (such as SOLITEX ADHERO) that self seals around fastener penetrations for this type of wall assembly because there will be many penetrations with the brick ties and shelves. The ADHERO membrane is a great option for back vented brick assemblies.
Stucco
Wall assemblies with a stucco exterior finish don’t typically have a rainscreen. The windows are typically taped to the wall’s air barrier on the interior and then use the CONTEGA SOLIDO IQ to tape to the plaster exterior finish at the headers and jambs of the window. The CONTEGA SOLIDO IQ tape is fleece covered so it can hold a plaster finish. Wall assemblies with stucco finishes should use metal pan sills and need attention to flash the corner detail from the jamb to the metal pan sill – this is often a high-risk location.
CMU / Multifamily
Larger building projects such as multifamily or commercial buildings are often not taping the exterior side of the window frames and are instead using a backer-rod and caulk approach for the exterior. If possible it’d be best to use an exterior waterproofing tape because it’ll require less maintenance, but the tape does need to be concealed and protected from UV exposure. On these CMU projects the WRB/air barrier (typically a fluid applied WRB such as VISCONN) should turn into the rough opening to allow an interior air sealing window tape. Interior window taping is best practice for large projects since it’s the easiest to quality control the install.
A quick interior air barrier window install option is to can-foam the rough opening to the window frame gap and then cut the foam flush to the window frame. And then install VISCONN over the shaved foam so the VISCONN air seals the window frame to the wall’s air barrier. The AEROFIXX or spray application of the VISCONN is very quick, but would require painters taping the window to protect interior finish. The can-foam could be creating a vapor retarding concern around the rough openings, but is a quick install and can act as a substrate for the airsealing VISCONN to bridge from the air barrier to the window unit.
