21-0403 Spray Foam in Cavity Application

QUESTION

We understand that the use of foam insulation is prohibited because it contains HFRs. For the most part, our project is using Red List compliant insulation products. However, in two limited instances detailed below we are requesting approval to make use of the I10-E12 9/2010 exception which states: Foam insulation with HFRs is allowed in certain application when space is limited, and alternative products cannot provide the required R-value performance.

First, our non-orthogonal building footprint creates irregular, often acutely triangular spaces where the floor joists intersect the rim joists at the perimeter of the building, as well as where the blocking between these elements further impedes access (see attached pictures). In our cold Canadian climate, the rim joist is an element we pay particular attention to when insulating and airproofing to avoid thermal bridges. Due to the narrowness and irregularity of these spaces, it is infeasible to properly install the vapour barrier and interior batt insulation in a satisfactory way, thus we must use foam insulation for the rim joists on two floors.

Second, our four rear balconies are cantilevered from the building, each resting on two steel beams that penetrate through the exterior wall and deep into the floor structure (see attached extract from the structural plans; the steel elements of the balconies are identified in blue dotted rectangles). A classic thermal bridge, this detail requires the insulation to be air-tight and to follow the metal profile perfectly to avoid condensation problems. We know of no other reliable way to insulate the thermal bridge except to use foam insulation.

For these two instances, we have chosen Greenguard Gold certified foam insulation that does not contain Red List chemicals, other than the HFRs.

ANSWER

Because the use of batt insulation has been maximized in framing cavities throughout the rest of the project, and because batt insulation would not permit the consistent positive contact needed for an effective installation at the odd shaped junctions and members in question, the project team may use spray foam to insulate at these locations even where they are within framing cavities.