Enclosure design principles Documents

BSD-106: Understanding Vapor Barriers — by Joseph Lstiburek — last modified 2008/10/17

The function of a vapor barrier is to retard the migration of water vapor. Where it is located in an assembly and its permeability is a function of climate, the characteristics of the materials that comprise the assembly and the interior conditions. Vapor barriers are not typically intended to retard the migration of air. That is the function of air barriers.

BSD-144: Increasing the Durability of Building Constructions — by Joseph Lstiburek — last modified 2009/04/22

The current building industry focus on durability is in part a reaction to the current perceived lack of it. Warranty claims and callbacks are viewed as increasing. Litigation and insurance costs are felt to be rising as a result. Another reason for the current focus on durability is the recognition that sustainability is not possible without durability. If you double the life of a building and you use the same amount of resources to construct it, the building is twice as resource efficient. Therefore durability is a key component of sustainability. It seems that one thing that both the development community and the environmental community can agree on is that durability is a good thing. What do we know about durability and how do we know it? The lessons of durability have come principally out of failure. Engineering is an iterative process of design by failure. Buildings are constructed. Problems are experienced. Designs and processes are changed. Better buildings are constructed. The building industry is in essence a reactive industry, not a proactive industry. It can be argued that the industry continues to do things until they become intolerably bad and then the industry changes. Examining failures gives us guidance on increasing the durability of building constructions.

BSI-011: Capillarity—Small Sacrifices — by Joseph Lstiburek — last modified 2009/02/21

An edited version of this Insight first appeared in the ASHRAE Journal. Water causes enough trouble by itself, but when we add salt we go to a whole different level, especially where porous materials are concerned. What is the deal with porous materials? Simple, porous materials are capable of wicking water large distances due to capillary suction. And when water can move large distances only bad things can happen.

BSI-015: Top Ten Dumb Things To Do In the South — by Joseph Lstiburek — last modified 2009/02/20

Joseph Lstiburek's classic list of building practices not recommended for hot-humid climates. This list was first posted on Building Science Corporation's website in 1997.

BSP-041: READ THIS: Before You Turn Over a Unit — by Building Science Corporation — last modified 2008/09/09

How a unit is turned over and maintained has significant effects on the control of asthma triggers and other indoor and outdoor contaminants.