House in Progress Diary

Sistering the Joists for Floor #2

The joists that support the second floor of our house are already more shallow than we'd like.

They are 6 inches deep and set on "16 and a half inch" centers (meaning, if you measure from the center of each joist...the joists are 16 1/2 inches apart.)

The size of your joists, the material they are made of, their span (or their length before they are supported by another vertical wall or post) all are part of the equation that helps you to determine how much weight they will support. (You can click at my poor illustration attempt to enlarge this picture of joists, a beam and floor. Many apologies to "This Old House".)

You want to avoid cutting into joists if you can. Any material that you cut out of a joist (and there are better ways to do this than others) can weaken the support the joist . You CAN cut up to a third out of a joist to run a pipe or BMX without compromising it too much and depending upon the span...but it's best to avoid testing this out too thoroughly. The beam looks like the backbone of the house, but the joists look like the ribs of its back. And you aren't going to want to break the back of your house!

When we look into the ceiling of our first floor bathroom, we see potential trouble (these are the joists under the 2nd floor bathroom...Click to enlarge):

The most disturbing cut in the joist was for piping that drains the bathtub.

The second floor bathroom was added in 1951. (Our house was built in 1914.)

To do this, if you recall, they turned a very narrow bedroom into a strangely configured bathroom--put it in a cast iron tub, a toilet, a sink. These all needed plumbing for hot and cold water plus drains and vent stacks.

If you follow the arrows above, you'll see that ALL of the plumbing comes up ONE wall, even though there are fixtures for 3 walls upstairs. At start, follow blue arrows to the water for the shower and bath, purple arrows for water going down the drain, and a green dotted line for a vent pipe that goes between floors to the vent stack.

The hot and cold lines for the sink? That starts in the same place, snakes between the floors and then THROUGH the hollow in the bathtub where it "folds" over. Out the back of the bathroom wall, into the attic, bends round its second corner and ends up back in the bathroom where the sink is. The drain and stack for the sink? We're still trying to find that.

These are the plumbing problems were are to unravel before we close the walls downstairs back up.

Yuck.

Posted by jeanne on January 27, 2004 at 8:51 PM (1)