Screwing Up the Floor

Before we closed on the purchase of our house, the seller agreed to have the joists supporting the downstairs bathroom floor replaced. This room is the only one on the first floor not supported by concrete slab; below the bathroom is the original footprint of the house, which was built to be a spring and pump house in the 1920s. The space is a five-foot deep cellar, into which all the piping and equipment for water filtration and heating has been crammed. It's a maze of copper, PVC, and wire, whose complexity and tightness are only hinted at in this picture:

The gentleman who replaced the flooring in our soon-to-be house may have had some screws loose. Or he may not have had enough experience replacing floor joists in complicated settings. In order to hang sister joists next to the old ones, he discovered that piping and tubing got in the way. To solve this problem, he decided to cut the three center joists of the room right down the middle, like so:

 The problem with cutting through a floor joist is that, no matter how many nails you use to tie the two halves together, the joist is going to sag. This principle holds true especially in a bathroom, which sees a lot of traffic and holds a clothes washer and dryer. Thanks to this repairman's structural decision, the center of our bathroom floor had been descending over the last six years, to the tune of about two inches.

I had several conversations with my DIY heroes at 88-BC, our local building supply joint, and we settled on a plan to raise the floor by jacking it up. One of the guys in my congregation, who has probably put up, torn down, and modified more barns than I've ever stepped into, kindly allowed me to borrow two screw jacks which easily lifted the floor:

 (Thanks, Harold! You saved me a couple of hundred dollars renting or purchasing my own for a single use.)

The screw jacks pressed up on a pair of 4x4s that in turn lifted a single 4x4 set cross-wise under the four joists in the center of the room:

So as to avoid cracking any of the floor, I raised the joists in increments (though I was told by Harold later that my progression was overly cautious). I wrote on the 4x4 the distance from floor to joist after every turn of the screw:

 Then I inserted 2x4s as scabs along the length of the severed joists. The insertion was probably the hardest part, because the piping and electrical work made it impossible just to lift the board into place. It was a headache to weave these boards--all while crouched in a cellar space twelve inches too short for my frame--between tubes and pipes to get them in place. Plus I had a four-and-a-half-year-old helper, whose insistence that she "turn off the light to see if her pencil drawing will glow in the dark" did not speed things up. But I did it with eight boards, then anchored them in place with TimberLOK screws (handed to me by my Big Kid helper, who was genuinely helpful at this point), which my trustworthy sources tell me are as strong as carriage bolts in this application:

With a little prayer, I removed the jacks. Only a few complaints sounded from the floor as it returned to supporting its own weight. I went up stairs to the bathroom. Lo and behold, the floor is still hight and level. I hope that it stays so for a very long time. Should it sink again, I'll have to call in the pros.

Thanks to Jared and the crew at 88-BC for their expertise and assistance!

~ emrys