Much of the GBA team was in attendance at the 14th-annual Westford Building Science Symposium last week. More commonly known (and maybe more accurately described) as “Summer Camp,” this invitation-only, three-plus days long assembly of several hundred people involved in building science is a geek’s delight, featuring long days of lectures followed by dinner, drinks, and music until the wee hours. How we manage to get up and function each morning is one of the biggest mysteries at camp. If any Twitter fans are interested, look for #bscamp in tweets from this week to learn more.
While the festivities sometimes overshadowed the daily talks, a lot of very serious business went on between 8:30 AM and 4 PM every day, much of which really made me think.
On the first day, Bill Rose gave a great talk he called “12 Easy Pieces: Short Exercises in Building Science.” He moved through some of them so quickly that I was hard-pressed to take enough notes, but he really got us thinking.
Probably my favorite point he made was about the separation of building and architecture. I was always aware that the two professions diverged in relatively recent history, but his analysis was that in 1672, Louis XIV’s finance minister, Colbert, gave architects privileges that undermined the builders’ guilds and syndicates developed in the Middle Ages. Architects were given powdered wigs and access to kings and to academies of fine arts. After this, builders kept their knowledge to themselves, refusing to teach architects about building, leading to many of the disconnects we have in construction today.
Vapor barriers protect architects, not buildings
Rose also spoke at length about vapor barriers and retarders, and the value of prescriptive measures in building codes. He pointed out that vapor barriers don’t protect buildings; rather, they protect architects.
He also pointed out that when prescriptive measures are put into building codes, they usually develop constituencies and industries to support them. Businesses develop around these products and are financially invested in maintaining the requirement rather than assuring the highest-performing buildings.
Many of these measures don’t ever accrue as benefits to the building owner; they primarily work to reduce liability to the professional who specifies them. I particularly liked Rose’s comment that there is an “on” button for most of our behavior (one recent example being taking our shoes off at airport security), but we rarely see an “off” button. That is, no one ever questions the value of the effort, and it just stays in place forever. This relates to building science and vapor barriers as much as airport security.
Rose set some criteria to evaluate prescriptive requirements for buildings, which are good rules to live by:
- Is it critical?
- Is it necessary?
- Will the building perform badly without it?
- Is it sufficient?
- Will compliance result in satisfactory performance?
- Is it policed?
- Is there a mechanism in place to revisit the questions of criticality, necessity, and sufficiency?
Challenges and questions
Rose challenged us to find people who are willing to question prescriptive measures and help make them disappear when they are no longer appropriate. This last thought leads me to a question I am going to pose—at the risk of being skewered by some of the major building science geeks that populate this site, mostly from northern climates.
Having worked in the mixed humid South for my entire career, I find the cold-climate bias of most building science a little frustrating. I don’t have any experience with most of the condensation issues that arise in severe cold, so I defer to those experts on most occasions. That said, it occurs to me that it might just be possible that the recommendation for vapor retarders in cold climates is more a response to the possibility that other things could go wrong, rather than a necessity in all conditions.
Later during the symposium, there was a presentation on spray foam insulation, and during one side discussion, the subject of open-cell versus closed-cell roofline insulation came up. Being a geek from a mixed climate, where vapor retarders generally aren’t recommended, I lean toward open-cell foam—to which the cold-climate geeks say there has to be a vapor retarder to prevent vapor from flowing through the insulation and condensing on the cold underside of the roof deck. This was not the first time I have had this conversation. I was almost beaten to a bloody pulp by some angry builders in Montana for making similar comments.
So my question is, if the moisture is adequately controlled inside a house in the winter, is the vapor retarder necessary, or is it just one of those things that is installed to protect architects and builders from liability? I hope that the cold-climate guys don’t put out a contract on my life for raising this question. I just want to start some discussion and see if my theory has any validity. I welcome your comments.