What is a Building Envelope?

A building envelope is a term which is used a lot in the construction industry, but there is little use of it in the general public. The term is used to describe the entirety of the barrier/barriers generated by a building, i.e. the protection against water, air and heat and general climate control. Therefore when somebody tells you that your building envelope is damaged or isn’t performing as it should be, what it means is that the barrier between the external and the internal isn’t working properly, for whatever reason, and therefore the climate inside the building isn’t being controlled. A good example would be a leaking roof, which will raise the moisture content in the air of the building, but a draft which comes into the house through small gaps underneath doors can also be seen as a deficiency in the building envelope.