After passing the third new construction, four-story, brick condo building on just one block this afternoon, I commented to my friend that we have to stop using brick veneers in Chicago. It partially made sense when we used it for structure to hold up the floor and roof above (or to an extreme example seventeen floors – see monadnock building), but no longer seems functional since brick is not used to support loads in new construction, typically.
Most buildings that appear to be brick are simply made up of a brick veneer which hides the light wood frame construction behind it. The wood frame is the complete structural system and also provides a cavity for insulation, usually in the form of fiberglass batts. This assembly relegates brick purely to an “aesthetic” gesture status. And sustainable design, or good design for that matter, has no place for purely aesthetic gestures.
There is a rationale in this city that brick equals grandeur, however its ubiquity has demoted it to a run-of-the-mill material in my opinion. The city even tends to require that most public housing or discretionary projects be brick adding to its commonality. On the surface it apparently evokes feelings of a stately residence, but it is simply gingerbread, no more useful than crown molding. This is not a debate of minimalist architecture versus the ornate, but a fact of practicality and function.
All that said, we can still design a sustainable wall system out of masonry, it just has to be turned inside-out. Since masonry is an optimal thermal mass material it should be placed so that it is exposed to the interior. A brick veneer wastes brick’s thermal mass excellence on mere decorum. This, during the cold months, will allow the heat in a space to be absorbed during the warm hours and released during the cool hours. Brick cannot achieve this if it is placed on the exterior of a building with insulation between it and the occupant. The exterior side could then be an insulated wood frame wall which will prevent the heat loss that is obtained from the thermal massed masonry.
Later the same day I toured a LEED certified house in Ravenswood, and wouldn’t you know, the house actually implemented this “reverse wall” assembly on the north facing facades. The north wall was constructed of 8″ concrete block at the interior face, a 6″ air gap, then a panelized 2×6 wall with spray foam insulation, and finally a fibrous wood rain screen as the exterior finish. The south wall was mainly glazing with an overhang above that allows direct sun during the winter months, and shades the sun during the summer. It is claimed that the 20″ thick assembly could achieve an R-35 rating. Counterpoint, at that thickness they could have achieved an R-30 to R-40 rating with strawbale construction (probably would have saved quite a bit of money too).
Ornament for ornament’s sake is not a sustainable practice, or even good design practice really. There is no reason archaic materials can’t be used in modern buildings, but they should be re-purposed so that we take advantage of their inherent characteristics.
