Insulation with GDDC
Insulation is the heart of the system. EIFS are extraordinary in appearance but the high ‘R’ value is where the real inner beauty resides.
Almost all EIFS use expanded polystyrene insulation (EPS) with an RSI value of 0.68 per 25mm (‘R’-Value 3.85/inch). Most systems are evaluated with 100 mm (4”) or more insulation. Mass walls such as concrete or masonry can be maintained at almost constant temperatures. Stud walls can have cavity insulation plus massive exterior thermal insulation.
EIFS provides unique design flexibility given the ability to easily shape insulation. Cornice, quoins and carving can be done with the insulation to create style or signage.
GDDC – Geometrically Defined Drainage Cavity – In Canada, Part 9 National Building Code requires GDDC insulation to accommodate for substrate irregularities that may cut off the space between vertical adhesives ribbons. In Ontario, the insurer for most architects requires GDDC insulation for all EIFS projects. The user should be aware that GDDC is more complicated to install and following manufacturers instructions is important.
The EIFS drainage cavity, either with vertical ribbons of adhesive or with properly compartmented GDDC, has been demonstrated not to compromise the effective insulation value of EIFS cladding.