Enhancing Envelope Design – Part I
Canadian Funding Corp will be dividing this healthy highrise piece into several posts due to the length and detailed nature of the material.
Introduction from Canadian Funding Corp: What is the building envelope?
The building envelope consists of the materials, assemblies and components that separate the interior of a building from the exterior. It includes such elements as walls, windows and doors, roofs, floors and foundations. The function of these elements is to enclose space in such a way that appropriate interior environmental conditions (temperature, humidity, air movement, light) can be maintained.
Premature failure of building envelopes occurs in many buildings throughout the country. These failures result in the deterioration of the exterior facade of buildings, damage to building interiors, dangerous long-and-short-term structural situations, and potential adverse health effects to occupants as a result of exposure to molds.
The knowledge and technology required to design and construct building envelopes that are free of problems is now available. A more durable envelope, requiring less maintenance, is the result of improved understanding of applied building sciences, improved detailing on construction drawings, and greater attention to detail in the construction and commissioning of the building envelope.
By understanding the movement of moisture through the building envelope, whether the moisture is from the outside or inside, the primary cause of premature deterioration can be controlled. Enhanced envelope performance can be achieved through greater envelope airtightness, improved water management capabilities, and the application of pressure equalized rainscreen systems and proper water shedding details.
The following section provides an overview of improved approaches to air barrier systems, rainscreen design and commissioning requirements, water-shedding wall construction, and improved practices relating to the design and construction of parking garages and roof systems. In each case, changes to the design, construction and commissioning of the building envelope are required to ensure improved durability.
Air Barriers
Despite the importance of the air barrier to overall building performance, air barrier technologies are just beginning to be understood. Consideration of the air barrier system is often not fully integrated into the design process.
An effective air barrier (or more specifically an effective air barrier system, made up of all the materials, components and joints functioning to prevent the migration of air) is an essential component of a well performing building envelope in all climatic regions. The effectiveness of rainscreen designs, improved insulation levels, ventilation and interior comfort are each dependent on air barrier performance. The air barrier system will restrict the movement of air through the envelope, thereby reducing the primary transfer mechanism of moisture. Control of air movement will also improve comfort, envelope durability, and energy efficiency.
Canadian Funding Corporation will continue on the subject of air barriers in a following post and in the spirit of the healthy highrise. We hope that this CMHC material will prove useful.
Meanwhile here are two videos provided by Canadian Funding Corp. on the building envelope and financing issues.
Canadian Funding Corporation and Moishe Alexander issues high LTV commercial loan in Cambridge Ontario to fund the purchase of a variety store. Michael Spiro, attorney, closed the deal.