Retrofitting the Rockland Public Library: In the Basement
The main part of the Rockland Public Library's basement runs beneath the new section, shown at the top of this diagram. Other than the Mechanical Room, this is all finished space, with rooms for teens and toddlers, meetings and book sales.
At least, it was mostly finished. The rim joists, where the library structure sits on the foundation walls, is less-than-finished. The 16" gap between the top of the drywall and the ceiling revealed gaps in the pink fiberboard insulation. The rim joists in the old section were completely uninsulated.
Those gaps made a difference you could feel throughout the library and see with a infrared camera. The infrared picture (left) shows temperature differences. Yellow is warm, purple is cold, and black is colder still. We sprayed the existing insulation with a top layer of high-density spray foam to cover areas that are missing insulation and seal any air leaks that are present. When that was done, we covered the spray foam with a fire-rated intumescent paint, per current building codes. Now it looks like this:
Since foundation air leaks are a major source of heat loss, this retrofit will significantly improve the building's ability to stay warm.