The installation of acrylic coatings started in the 60 years. Two decades later, rot and mold problems were discovered in the wood structure behind this type of cladding, particularly at the corners of the openings, at the intersection of the walls and roof, and at the base of the cladding. .
Former Facility (SIFE)
Laying a system insulation Coated Facades (SIFE) consists primarily of expanded polystyrene foam (EPS) insulation panels with a ribbed backing and an exterior acrylic finish. At the very beginning, the polystyrene panels were placed directly on the membrane air barrier and the intermediate coating without the presence of a air blade.
In our assessments, we removed the acrylic coating and the expanded polystyrene insulation, and found that the siding and the sill were wet, blackened and rotten. Sometimes there was even mold.
In some cases, the waterproofing system, at the base of the siding, had not been executed according to the rules of art. The metal flashing had not been slipped under the air barrier membrane and there was no gap between the acrylic coating and the foundation wall to ensure a proper drainage system. water that can pass through the outer skin.
At the base of the exterior cladding (at the junction of the acrylic cladding with the foundation wall), we have found, on a few occasions, that the waterproofing system has important deficiencies such as:
- The metal flashing at the base of the acrylic siding was not slid behind the air barrier;
- The absence of a waterproofing membrane at the junction of the flashing and the intermediate wood cladding;
- The total lack of a water drainage system at the base of the acrylic coating;
Note that the air barrier membrane must overlap all deck flashings at the "wall-to-roof" interfaces. In addition, there must be a clearance space between the acrylic coating and the roof. The water passing through the envelope, at the level of the roof flashings, flows along the metal flashings installed at the junctions to the lowest point of the flashings at this point. The water must be routed to the outside by a folding flashing, otherwise the water flows on the air barrier membrane to the base of the exterior facing. This situation explains the presence of dark circles on the air barrier membrane under the corners of metal roof flashings.
Water flowing through the outer casing, particularly at the corners of metal roof flashings, runs off the surface of the air barrier membrane. Arriving at the base of the siding, the water meets:
- An unsuitable sealing system that is not made according to the rules of the art;
- An acrylic facing that does not allow free flow of water to the outside.
The trapped water at the base of acrylic coating causes degradation of the structure behind the acrylic coating and mold formation.
After the occurrence of major damage in many buildings, the specialists realized that the water, which managed to infiltrate, remained trapped in the polystyrene and rotten the wooden structure. In this way, the rainscreen principle was not respected.
Since the 2000 years, the solution to these problems has been to "create a drainage and sealing barrier behind the insulation" (Perrier Guide).