The building envelope is really an assembly of building materials that occurs between the inside of the house and the outside of the house or simply put the outside wall or roof. These are made up of various elements including thermal barrier (insulation), vapour barriers, air barriers and moisture barriers.
In most areas of Canada, keeping out the cold is the primary technical role of the building envelope in a house. However, on the west coast this is not typically the case. Building envelopes primarily control and limit the infiltration of moisture as well as ensuring that moisture does not occur within the wall. These issues were brought to the forefront during British Columbia's leaky condo crisis where mold was accruing in condo building envelopes due to poor vapour and moisture control.
More recently, both provincial and municipal authorities have been working hard to change the ethos within the construction industry in BC. Recently addition have been made to the building codes that mandate rain screen assemblies are used on exterior wall assemblies in order to better control moisture infiltration. This was mandated for both condos and houses.
Recognizing the complexity of these assemblies, municipal and provincial governments have been turning to building envelope specialists in order to enhance the safety and effectiveness of construction assemblies. Energy consultants are now becoming commonplace to increase the thermal efficiency of the envelope and to minimize the amount of energy required to heat a house. These specialists are now an integral part of the design and construction process of building a house.
It is important to remember that unattended moisture in our envelopes is a serious health hazard and despite its technical nature, it is important to maintain a healthy environment for ourselves and our families. After all, this is where we live our lives.