Long term weathering effects on insulation in high performance building envelope
High performance buildings often require complex building envelop details to insulate and shade the building, thus protecting it from the harsh extremities of climate for reducing dependence on HVAC systems. Often building codes and simulation tools suggest tight envelopes that require insulation layering and minimizing thermal bridging from structural elements. However, in reality creating such complex assemblies may be challenging to construct, maintain and ensure thermal and structural performance with minimal degradation. Most commonly observed challenges are cracking of construction assembly due to several layers having varied thermal expansions leading to issues like structural instability, water seepage, mold and pest growth, fire hazards, thermal bridging and air infiltration. These challenges get even more complicated in Indian context due to prevalence of wet construction techniques involving RCC and Masonry. For instance, using XPS boards for roof insulation is a common solution to achieve desired U value over an RCC Slab. This requires several layers of water proofing and screed on which floor finish like tiles are laid. In few years tiles start to crack due to thermal stresses leading to unintended water seepage due to rains and moisture build up which rots the insulation and makes the roof surface unstable even at time sinking upon placing any load. This adversely affects the RCC Slab below and leads to massive expenses in repair and replacement.
