Workshop Review – Building Science Fight Club

On Thursday 2/4 we invited Brick & Wonder members and their teams or colleagues to join us for a Conversation hosted by Christine Williamson, Founder of Building Science Fight Club. (@buildingsciencefightclub)

Building science is an oft-overlooked corner of architectural design and building construction, but its value to owners, investors, developers, architects, and general contractors couldn’t be greater.

For owners, developers, and investors, building science is essential in risk mitigation, energy efficiency, constructability, and durability. For architects and general contractors, whose contractual liability for their built work is high, building science can mitigate risk, control water and air, and deliver projects that meet award-winning standards for safety and sustainability.

In this conversation, Christine led our gathered cohort through some of the most common mistakes and assumptions in construction and design, focusing in particular on water issues, which present one of the biggest risk factors in residential and commercial construction. 

Video + Audio Session Recap

Brick & Wonder members can access the full session recap including video and audio recordings here

Meet the Session Leader

Christine Williamson, Founder, Building Science Fight Club

Christine Williamson provides technical design consulting services to architects, developers, and contractors, assisting with design development and reviewing details and specifications to improve durability, comfort, and energy efficiency.  She also teaches architects, architects in training, and other building industry professionals about building science and construction. She is the founder of @buildingsciencefightclub (BSFC), an Instagram community dedicated to teaching building science and construction to architects and other building professionals. She received her bachelor of arts from Princeton University and her master of architecture from New School of Architecture + Design.

Christine Williamson + Building Science Fight Club Classes

Key Insights

We are pretty good at making sure our buildings don’t actually physically fall down. And we’re pretty good at making sure that they don’t burn down. We are less good and less consistent at dealing with leaks, condensation, rot, and mold.


When it comes to risk management, it’s really good to be able to identify what puts you most at risk for these types of failures? So, is it your window details, your balconies, your roofs?


You can always reduce risk by spending more money. But… what I’m getting at is having the right information to make the design of the building match our performance objectives, and the resources that we have available to achieve those those objectives.


Drainage is a design feature. We’re not draining these walls because something else went wrong. The drainage is not compensating for a failure elsewhere. It’s not like a lifeboat, where you’re only in the lifeboat if something else has gone terribly wrong! This is more like taking a bath. When you take a bath, you fill the tub, drain the tub, and the next time you take a bath, you fill it up again. And nobody thinks that the drain makes the tub defective. That is how it’s designed to work. So this is how drainage is how these walls are designed to work. And, and this concept is one of the most misunderstood parts of architectural design with respect to water management. Drainage is important in framed walls, and and it’s a feature, not a backup for when we’ve failed elsewhere.


For water filtration to be problematic the wetting a wall experiences must exceed its capacity to store and redistribute water for long enough to damage the materials that compose it.


In order for us to have a leak, we have to have these four things. We need a source of water. Then we need a pathway for water to travel from where it is to where we don’t want it to be. We also need a driving force to push water along that pathway. And we need something moisture sensitive to be damaged as a result. It has to create a problem for us. 

The reason this is so significant is because we usually spend all of our time and attention on pathways. We are obsessed with eliminating the potential pathways for for water to infiltrate our building our buildings, and that’s fine. But it is not the only strategy that’s available to us to mitigate leaks. And it’s not even, frequently, the most effective strategy.


The the one that’s most interesting is hydrostatic pressure, which is also a form of gravity. Wind, capillarity and surface tension are the other most most interesting ones. Dealing with these driving forces is really the low hanging fruit and water management. If we can reduce the forces that push water into our buildings and along our pathways, we don’t need to actually be perfect at either source control, or sealing our pathways.


So capillary action is is actually a form of surface tension. A practical example is when you dip a paper towel into a cup of water and watch the water wick through. The same thing happens with all kinds of building materials, particularly cementitious ones, like brick, stucco, and concrete. And incidentally, it’s also what brings water up to the leaves of trees, which I think is this pretty powerful example. Intuitively, we know that trees are very tall, which goes to show you just how far capillary movement can can transport water.


You can use furring strips which are essentially a foam strip being used as a spring behind the cladding. This is for drainage. And providing drainage like this is the number one lowest hanging fruit in terms of risk reduction in in buildings. It’s not upgrading to a fluid applied membrane or more expensive self adhered membrane. It’s providing drainage drainage. Matt is about $1 a square foot, which is an add, but it’s substantially less than a lot of other things that we do in our buildings. 


When had serious space constraints, we would use closed cell spray foam on the interior because we could get the biggest bang for our buck in terms of R value per inch.


The most complicated membranes to detail are the building papers at windows, if you look at the installation instructions it’s like 30 steps. Fluid membranes, self adhered membranes, and integral membranes are all super, super intuitive. You just seal whatever it is you’re sealing to the surface. That’s it. 


If the labor market in your area is not accustomed to using continuous exterior insulation, figuring those details out and coordinating another trade on the job can be difficult. So if you use something like Zip-R nothing else changes, you sequence the job the same way: you flash everything the same way, and that is good for risk reduction… That gets significant performance improvement at a relatively low cost and the scope of work stays the same. You don’t have to hire a different trade.


Sometimes people think: “Oh, well, I’m on the coast and the water load is really high, so therefore I need to seal everything up.” And they end up blocking drainage or not providing drainage, for example in windows. So I see that specifically in the coast. And the justification is: “We get a lot a lot of weather here.” Well, yes, that makes drainage even more important, not less important!


So variable permeable membranes work a lot like plywood works. So you can see that as the relative humidity increases, the permeability of the material either increases or doesn’t. So OSB stays relatively impermeable all the time. OSB is a pretty good vapor control membrane. Plywood becomes more permeable when it’s exposed to high relative humidities. Now this is often a really desirable characteristic because it dries if it’s if it gets wet, like in a leak, plywood is quicker to dry. What matters is where the inflection point on the [permeability] curve actually is.



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