What's in the Walls?

An interesting thing about gutting an old house to add insulation and new wiring, plumbing, and HVAC is what you find (or don't find) in the walls.  Our project house is definitely a vernacular house added onto and built with whatever the carpenters had.  Some walls had plaster, others old sheetrock.  When we got to the studs, we found that none of the walls had insulation and that the sheathing was flipped over and reused painted siding from another building.  Must've been pretty cold and drafty in there with the mountain winds blowing in winter.

We've also found that you can look straight up the wall cavities from the first floor to the second.  In other words, we've got balloon framing.  Today's buildings generally use platform framing where each floor is a platform extending to the outside wall and the wall studs are attached to the floor above and sit on the floor below.  With balloon framing, longer studs are used that reach from the base of the first floor to the second floor ceiling.  The floor joists are nailed to the wall studs.  The structure will usually have some bracing and the sheathing also helps to strengthen balloon framing.

Balloon framing doesn't meet today's building codes because the open walls create a chimney that can transfer smoke and flames throughout the building quickly and with devastating results.  So, one of our tasks is to add fire blocks in the walls.  We'll be insulating, which will reduce the chimney effect, but we'll also be adding 2x4 blocks that fit between the stud bays to further block airflow.  Since we've got real 2x4s and the distance between studs is probably not uniform, we won't be able to simply use big-box-bought lumber and cut all the pieces to the same size.  It'll be time consuming, but worth it in the long run for the safety and comfort of the new occupants.