Repairing water damaged cut joist to level a bathroom subfloor.

healeyx76 · 09-28-2012, 03:43 PM

I have some water damage to a floor joist, as a result the bathroom sags in one side approximately 1 inch. What can I do to level the floor?

Here are the pics with some labeling: http://imgur.com/a/e3azJ

Now for the details:
House was built in 1986
2 Story Cape-Cod on a dirt crawl, no basement.
Bathroom in question is in center of first floor.
As seen in one of the images, there is a steel I Beam running perpendicular to the floor joists under the 1st floor.
About 2 feet from the I beam is the down drain for the toilet. The joist was CUT some to allow for the down drain to be 12" from the wall when the house was built. We bought the house this year, it appears that in the past there was both a toilet leak around the wax seal, as well as a small pipe leak around the toilet-water supply. This lead to a slight rotting of the subfloor, which I have remove most of the offending area.
The floor is sagging about an inch, maybe a little more, in the one direction. (pics).

The other joists appear to be level from underneath, though I think the one joist is causing some strain on them.

The joist that had the water damage does NOT look rotten, at all. It just sags, like a mild hockey stick. I assume some of its weakness comes from the cut.

We're looking to install 1'x2' ceramic tiles in this bathroom, and I believe that joist, right there, has the weight of the shower, toilet, and load bearing wall that supports the 2nd story on it, which is why it has deflected so much.

There is not much give, if any, if I jump on the floor, or try to see if its weak. It more looks like a strong piece of wood that has deformed over time.

What would be the best path to repairing this so we can install tile? I will most likely remove the subfloor completely in the room, from wall to wall, and recut the ply, after leveling the joists.

Thank you for any suggestions!

Again the pics : http://imgur.com/a/e3azJ

GBrackins · 09-28-2012, 03:58 PM

if I understand correct when the toilet flange was installed they cut out some of the joist, and now it is sagging ..... for the one that has been cut I would install another joist adjacent to it.

what is the span of the floor joists, their size (2x8, 2x10, etc.) and their spacing (16" center to center, etc.)? if you have the floor open it may be a good ideal to install additional joists in between the others. once I the above information on your floor system I can make more intelligent comments.

healeyx76 · 09-28-2012, 04:20 PM

they are spaced at 16" and from the I beam to the front of the house runs about 16 feet. They are 8.5" deep. So 2x8.5x16'@ 16" spacing.

And yes, the one that was cut is now sagging.

To install an additional joist, do I need to jack up the sagging one so that the floor is level again first? And to do so, can something, say cinder blocks, placed on the dirt/sand crawl floor support the weight of lifting the floor?

And are you suggesting installing separate joists, say @ 8" in between, or sistering a new joist to the current sagging one?

GBrackins · 09-28-2012, 05:01 PM

8-1/2" is an unusual depth ..... typically I would have expected something like 7-1/2" or 9-1/2". not doubting your measurement but could you double check? it's possible they were cut down for some reason but would not be typical.

let's look at the span tables from the 2009 International Residential Code, the basis for most local and state building codes. http://publicecodes.cyberregs.com/ic...9_5_par020.htm they do not have a listing for 2x8-1/2

2x8 spruce (don't know your species) at 16" o.c. should only span 12'-3" max. 2x10 spruce at 16" o.c. should only span 15'-5" so you are obviously over spanned.
2x8 spruce at 12" o.c. should only span 13'-6", 2x10 spruce at 12" o.c. should only span 17'-3"

if they are douglas fir then you could get about 6" to 8" on your spans (see table).

did the floor feeling a little bouncy before? if so, do you want to make them more solid?

healeyx76 · 09-28-2012, 05:12 PM

Sorry, they're 9" measured, assuming the marks on my level are accurate : I was measuring the boxing for the entrance before. (So i assume the "9.5" " is rough size?)
Its also at an angle as the level is too long for the floor height. I think my tapes are in my toolbox which is in my GFs car.

healeyx76 · 09-28-2012, 05:17 PM

And the floors aren't really bouncy. I'm 180lbs and can't really tell anything when bouncing on it. I'm more worried about the added weight of tile in that bathroom, as well as possibly adding hardwood throughout the house. The biggest issue is the deflection as it'll end up ruining any tiling we do.

GBrackins · 09-28-2012, 05:25 PM

I'd would install another 2x10 along side of the cut on. with the flooring removed you should be able to push up the cut one til it's level and nail the two together. The spans I gave you were for 40 psf live load so I would think you'd be fine unless you were installing a two-person tub.

You could always put in a few more in the areas you are concerned about. nothing wrong with beefing up a floor. just a little wood and time.

I'm sure you'll get a lot more feedback once members get home.

healeyx76 · 09-28-2012, 05:37 PM

In order to level, is this something I can do myself? The crawl is a dirt/sand floor. Should I be looking to get say 2 screw jacks, some 4x4's and what for the floor? Cinder blocks? Thick cement pavers? Or can wood suffice. I'm just worried about the jack pushing down into the ground?
I think I can get the wood into the crawl through an external vent (I hope) as you can see the bathroom is small, and theres no way to get it in from there.

EDIT:
Also the cut one still has to be cut in order for the soil drain from the toilet to be 12" from the wall. I guess I'll just sister one in on the other side of it, and maybe while I'm down there put in another to strengthen the next one.

EDIT 2 : Another question. Is there a RATE at which I should raise the floor? Its off by about an inch, should I go 1/8", 1/4" etc per day or can I do it all at once without damaging the walls/etc.

GBrackins · 09-28-2012, 05:50 PM

if you cannot sister another one to the cut on because of the flange, then install one close to the cut one on each side as your stated.

as far as raising up the cut joist, you could use a wooden block on the ground. measure from it up to the bottom of the cut joist. cut you a 2x about 3 or 4 inches longer. sit one end on the block and the other end against the bottom of the cut joist. then use your hammer to drive the 2x into place lifting the cut joist. make sense?

mae-ling · 09-28-2012, 06:00 PM

Once it is tight we usually only go 1/4" inch/day.
the 2x4 (or 6) works good to jack it up in a low crawl space and if the chunk on the ground don't sink much you may need less then the 4" extra length, good place to start though.
A bottle jack works well also.

healeyx76 · 09-30-2012, 01:22 PM

So my current problem is that on the sagging joist, the toilet down drain is on the cut side, and a shower drain is on the other. The toilet drain must remain where it is to be 12" from the wall and we don't want to move the shower.

So that means, with that plumbing there we CANT? sister a new joist to it?

I'm not even sure how to level it as I can't put in a 2x6 to span three joists and level at the sag point.
Would the best bet be to drop all the plumbing down another inch or three? Theres even water lines that go right up agains the joists. It makes it very tough to get anything in there.

Would it be possible to completely forget sistering a new joist in, as the house was built in 1986, the sagging is mainly due to the cut for the plumbing, the toilet above it, and some slow water damage (though no rot or mold/mildew).

So would it be OK to just:
Jack up to level.
Put in a concrete pylon base with a a 4x4 mounted to a 2x6 spread across three joists (16"x2 span). And that can support any new weight from the bathroom remodel (no tub, just tile) as well as level the floor, without moving ALL plumbing to sister a joist in.
Remove level.

As there is no more water leak, the house isn't that old, I can't imagine this would be a band-aid, as the problem has already been fixed.

I attached the overhead and side layout drawn up in MS paint:

GBrackins · 09-30-2012, 02:54 PM

try this ...... get the new joists as close to the drains as you can

mae-ling · 09-30-2012, 05:22 PM

Healey - Thanks for the excellent diagram!!!!!

What GB shows is how we would do it even in new construction. Just alter the spacing at that area.