Sometimes coincidence is your savior. I discussed our brick work with Martin Bazula, a restoration mason here in Chicago, and shared our goal of super-insulating the building – from the inside. Martin paused, thought and proceeded to explain to me that these old common brick walls were not intended to be insulated. In fact, the absence of insulation is somewhat their lifeline, helping with rain water and moisture management on and in the wall, and reducing the number of freeze-thaw cycles.
I almost had kittens! We finally found our dream home with a masonry shell. I already gave up the idea of insulating from the outside. And now I learn that the masonry shell, which was so important to us, may not be compatible with our insulation goals and ultimately the zero-energy objective!
Did you think that brick is impervious to water? Think again! Common brick is a like a sponge. Did you ever notice how masons dump or soak brick in water before they lay it? That is to prevent a dry brick from sucking all the moisture out of the fresh mortar during the curing process, which may lead to cracks. Plus, the mortar joints are also porous and act like sponges. So how do these brick walls, such as ours, help with the rain control and moisture management?
It actually is one of the oldest strategies out there. The Romans used it. It’s called storage or mass walls.
“This approach requires the use of an assembly of materials with enough storage mass and moisture tolerance to absorb all rainwater that is not drained or otherwise removed from the outer surface. In a functional mass or storage wall this moisture is eventually removed by evaporative drying before it reaches the inner surface of the wall. “
Reference: Building Science Digest 013 (Rain Control in Buildings)
The challenge of insulating such storage or mass walls, which Martin Bazula pointed out to me, was confirmed in another article I researched:
“Adding insulation to the [storage or mass] walls of such masonry buildings in cold, and particularly cold and wet, climates may cause performance and durability problems in some cases.”
Reference: Building Science Digest 114 (Interior Insulation Retrofits of Load-Bearing Masonry Walls in Cold Climates)
Great! What’s next? I hope a solution to this problem!
You can contact Martin Bazula at mbazula@hotmail.com
Tags: insulation, research, water