What’s wrong with the picture below?
This 1890’s Victorian-era home in Toronto is being renovated and the early signs don’t look good. The dimensional lumber sheathing is exposed after 120 years and what an historic and great opportunity to install an air barrier and continuous insulation on the outside to go with those nifty black framed windows.
At the very least, this reno has two strikes against it: poor detailing for energy efficiency/comfort and a complete disregard for durability due to eventual rain water intrusion around the windows.
First the Air Barrier, then the window…
The roughest opening I ever saw. A good renovator lines the rough opening with an water tight Self Adhered Membrane (SAM) on the sill with lapped edges, then lines the top and sides with a breathable air barrier. These RO membranes are tied into the exterior (weather resistant) air barrier and lapped to “drain the rain” as Dr. Joe says. Better yet, flash the RO with a liquid applied air barrier.
Once the windows are installed, it’s nearly impossible to achieve a good air seal if planning on using and exterior air barrier. It’s also game over for lining the window’s rough opening with a sill dam to prevent water from getting into the wall assembly below; remember what Joe Lstiburek says about water leaking though windows “There’s only 2 kinds of windows; windows that leak and windows that will leak.”
It’s a clear sign that many renovators in the GTA aren’t qualified or educated about proper building envelope detailing. Nothing a bit of hands-on training can take care. Although there’s no hands-on the OHBA’s Institute of Building Excellence offers renovator training for building science in order to get renovators thinking about these details.