Floor joist sistering question

[Neil]

I have a floor joist that is sagging where the joist was drilled through to allow for passage of the hot water heat pipe. Naturally this hole was made in pretty close to the exact center of the joist and they never sistered it as they should have done to begin with. To make matters worse, the previous owner had a grand piano sitting on this spot.

There's no splitting or cracking, but the joist is clearly sagging about 1/2" in the middle. It's the end joist, and the floor has settled enough that the quarter round now dips slightly below the baseboard.

I've jacked up and sistered rafters before but am a little unsure how to approach this since the hot water pipe runs directly under the joist preventing me from jacking up the joist directly.

Is it acceptable to lift the joist with a sistered member attached to the half of the joist with the pipe and then fasten it to the other once it comes up to level? If so, how do you gauge an appropriate gap on the new member so that you can jack it up correctly?

Thanks for any advice. We moved some furniture around so that it's visible and it's driving me crazy.

[Doug Miller]

The piano is the cause of the sag, not the hole (unless it's a really *huge* hole). The exact center of the joist is precisely where the hole *should* be.

Above, you said the joist was drilled for the pipe. Here, you say the pipe is

*under* the joist. Do you mean the joist was notched at the bottom?

"the half of the joist with the pipe"?? Isn't the pipe attached to (or passing through) *all* of the joist?

First advice is to post a picture of the joist and pipe somewhere. Your description doesn't make sense.

-- Doug Miller (alphageek at milmac dot com)

How come we choose from just two people to run for president and 50 for Miss America?

[PJx]

Remove the pipe temporarily while you properly fix the joist. Use strings in both directions in the room and jack til it is slightly above level as it will settle over the weeks ahead. PJ

[Neil]

The joist is drilled through vertically, not horizontally. The hot water pipe goes straight down thru the joist from the baseboad in one room and runs underneath before turning back up (through the another joist) to go to a baseboard in another room.

A top view would look like this ... _______________ ______O________

and a side view like this ...

[George E. Cawthon]

Just a comment first, What kind of idiot would have drilled through the joist instead of movingthe pipe a little bit? Assuming the joist is 1-1/2 x 8 inches and the pipe is 1 inch outside diameter, the plumber made it into a 1/2 x 8 inch joist. Jees!

Yes you can jack the sister. Attach the sister with two

3/4" bolts about 3 inches each side of the hole for the pipe and about 1/3 of the way from the bottom. The dimensions are not critical but the closer you get to the center of the joist and the closer you get to pipe the better pivot you have and the less push end wise. To reduce the push end wise as you jack, make the hole in the original joist slightly larger than the bolt or cut the holes with a chisel on the outside edges to make the hole more of a slot and use large washers at the head and nut ends and don't tighten so that they dig into the wood. You need to keep the bolts back aways from the pipe and in the lower half of the joist. Jack the sister slowly. I would use a level on a straight board on the floor and watch the baseboard crack. When you get it finally up your sister will be fairly parallel with the bottom of he joist, but the top won't touch the floor because you started with a sag. Nail, screw, or bolt the sister to the original joist when you get it where you want it.

If you want to get really wild, sister two pieces with a gap of about 1/2 inch at the hole. Put a board under this and jack up. When level sister another piece on top of your split sister. That would give you three joint thicknesses.

[Curtis]

Naturally this hole was made in pretty close to the exact center of the joist > >

If the hole was centered in the depth of the joist the effective strength has barely been reduced. The sagging most likely was due to the dead load over time.

Spars in aircraft wings have lightening holes for nearly the total span.

[Doug Miller]

Wow. That's amazing. The plumber who installed that is an idiot.

OK, here's what I'd do:

1. Get *two* 2x8s (or whatever size your joist is) by at least six feet long.
2. Attach one on *each* side of the drilled joist, aligning the centers of the sisters with the drilled hole. Attach each sister with only about six nails, in rows of three about six inches each side of the center.
3. Place jacks under *each* sister, right next to the drilled hole, and raise the floor *slowly* (1/8" per day **maximum** rate) until it's level.
4. After the floor is level, nail the sisters to the joist along the remainder of their length.

-- Doug Miller (alphageek at milmac dot com)

How come we choose from just two people to run for president and 50 for Miss America?

[George E. Cawthon]

If you read his second explanation you find out that the hole is center in the narrow edge and reaches from the top to the bottom of the joist. This would effectively change a

1-1/2" thick joist into a 1/2" thick joist assuming the hole is 1' in diameter.

[Walt Conner]

While I am sure there are several "good" ways of solving your problem, I would not put short pcs. on each side but rather, run a single new full length, or as nearly full length as possible, joist on the side with best access. Raising the floor in steps is a good idea.

I just had a similar problem where an idiot had cut completely thru one of a pair of double joists and carved into the second one below a two story plastered partition wall inorder to run a drain line. Putting a third joist in an already less than full spaced area left a very close nailing situation which I solved by cutting off an unused air chisel for a cheap muffler impact cutter and using it as an air nailer. A little hard to hold on the nail but really drove them.

Walt Conner