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in need of advice
broken floor joist under bathroom

We recently uncovered an old problem in our 120 year old home. It is a broken floor joist under the bathroom. We suspect that the joist had broken during a 1950's renovation of the bathroom. The broken floor joist explains the cracks in the bathroom floor and why the floor in the bathroom and adjacent bedroom has dropped about an inch away from the wall. The cast iron tub has also become separated from the tiled wall as it has dropped a bit also. Nothing seems to have moved any further in the 5 years we've lived here.

My concern is causing more damage to plumbing and walls by having the joist jacked back up to its original position and then reinforced. Would it be better to reinforce the joist in its current position to prevent further collapse instead? There are no signs of any movement in the 5 years we've lived in the house.

JLMCDANIEL
Re: broken floor joist under bathroom

With the damage you already have , I would recommend jacking and sistering with ΒΌ" plate. The broken joist is causing strain on other joists and the walls which can lead to further problems down the road.

Jack

jkirk
Re: broken floor joist under bathroom

im with jack on this one, get a jack post to jack the broken joist up back to "level" or "true" with the other joists, then sister a new joist to the side of the bad one using both glue and screws. .

make sure the new joist is sitting on the bearing wall, it may fit too tight to get it into place. if this is the case its okay to rip the joist down by 1/4" or so to give you room to move it, then shim it hard up to the underside of the floor sheathing then sister it to the old broken one.
once that is said and done if the floor itself isnt finished screw teh floor boards/plywood to the new joist to make hte connection that much stronger

keith3267
Re: broken floor joist under bathroom

I agree with the above. By jacking it up, you take the strain off the plumbing etc. It will go back to where it was originally installed.

If there is room, I would sister the joist on both sides. The sisters need to run the full length of the joists as well. In order to do that you usually have to cut down the joist on each end. Cut down the length of the sisters about an inch from the bottom for about 12", and terminate with a slanted cut that goes for a couple more inches. Save these pieces. Install the sisters, then wedge these pieces back into place, then use a regular wood wedge to further raise the sisters to the original level of the floor. then bolt into place with through bolts, washers and nuts.

jkirk
Re: broken floor joist under bathroom

hmm interesting technique with the wedges, never done it that way. may have to try it. i usually just take a check out of the wood then shim it up with lvl shims

in need of advice
Re: broken floor joist under bathroom

Thank you to all who have posted in response (and also those who will) to my problem. The advice is great! Thank you for your help. I am so glad I subscribed. :) Here we go...

HoustonRemodeler
Re: broken floor joist under bathroom

When sistering the joists usung 2x dimensional lumber, use PL Premium adhesive along with 3" decking screws properly spaced.

When jacking the old joist, raise it back to original height plus a little more to allow for settling when the jacks are taken away.

keith3267
Re: broken floor joist under bathroom
jkirk wrote:

hmm interesting technique with the wedges, never done it that way. may have to try it. i usually just take a check out of the wood then shim it up with lvl shims

I believ e I saw it on an Ask This Old House show.

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