Schöck Isokorb® Structural Thermal Breaks.Insulate concrete-to-concrete and concrete-to-steel balcony connections.
Reduce heat loss by up to 90% while preventing mold growth where balconies penetrate the insulated building envelope.
Uninsulated balconies penetrating insulated building envelopes act like cooling fins, creating a thermal bridge between the cold exterior balcony and the warm interior structure that supports it, exposing the developer to potential short- and long-term problems.
Problems caused by uninsulated balconies
- Cost and environmental impact of wasted energy
- Condensation in interior cavities resulting in mold growth, respiratory problems and associated liability
- Discomfort due to cold interior surfaces
- Noncompliance with new energy code requirements
Conventional balconies waste energy, chill floors, cause mold growth
Because of their load-bearing requirement, conventional balconies are designed as extensions of the concrete floor slab within the heated building envelope. As such, they create a thermal bridge in the otherwise continuous insulation of the building envelope, rapidly conducting heat away from the warm interior, through the insulated envelope and into the exterior environment.
For decades, wasted heat and cold interior floors were accepted as unavoidable outcomes in North American buildings constructed with balconies.
Because these buildings also leaked air profusely, interior humidity levels equalized with low exterior humidity levels (typically 18 to 25%) during winter months. Forced hot air typically vented at or near the cold balcony penetration further ensured that interior humidity remained too low to reach dew point, form condensation or support mold growth.
Airtight vapor barriers solved one problem, caused another
Modern buildings wrapped in airtight vapor barriers require less heat and retain more moisture, producing interior humidity levels of 35% to 50% (typical) during winter. While this humidity increase benefits energy efficiency and human comfort, it also allows the interior air to reach dew point, form condensation and support mold growth where cold balconies penetrate the interior side of the building envelope.
Mold can be growing on the inside face of sheetrock, studs and insulation — and occupants can be breathing it in — years before it becomes visible on interior ceilings and walls, exposing the developer to significant remediation and liability risk.
How Schöck Isokorb® Structural Thermal Breaks support balcony loads, cut heat loss and prevent mold
A Schöck Isokorb® Structural Thermal Break (STB) is a fabricated assembly that is cast into the concrete floor slab at the location of the building insulation layer. The STB insulates the interior floor slab from the exterior balcony while transferring the loads imposed on the exposed slab edge or cantilevered steel structure back to the interior floor slab, significantly reducing heat loss.
Insulating a balcony with Schöck Isokorb® offers multiple benefits:
- Reduces heat loss through the balcony by up to 90%
- Reduces heating energy consumption for the overall building by up to 14%
- Reduces heating system capacity requirements by up to 14%
- Increases warmth of interior floors adjacent to balconies by up to 27°F/15°C
- Prevents condensation and mold formation adjacent to cold balcony penetrations
- Compliance with new energy codes requiring continuous insulation
STBs for concrete balcony construction contain components that are cast into the concrete floor slab on the interior side, and into the concrete balcony on the exterior side The STB is engineered to carry the same design load as a conventional reinforced concrete balcony.
STBs for steel balconies on concrete buildings are equipped with rebar for casting into concrete floor slabs or other concrete structural elements on the interior of the building envelope, and high-tensile threaded rod for fastening to cantilevered steel balcony structures on the exterior of the building envelope.
A half mile of continuous balconies at Westerleigh Retirement Residence wrap the south and west sides of all seven floors. Structural thermal breaks prevent cold exterior extensions of warm interior support structures from wasting heat, chilling interior floors and causing condensation that can encourage mould growth.
Cantilever and loggia style balconies on residential apartment building. Concrete-to-concrete and concrete-to-steel Isokorb® STBs were used on this project.
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