Enroute to installing a new shower I find this giant hole cut out of the floor joist of the 1800's historic schoolhouse I call home.

Crazy thing is, the new shower placement...literally two inches over...makes more sense above ground and accommodates that pesky code rule that you actually have to be able to look down a drain and see the bottom of the p trap.

I'd hate to close up the floor if I could have done something to help repair that joist. I enjoy building things in general, but projects around this old schoolhouse are extra special. I get to see things like these old joists and imagine the builder that first put them there in the first place so long ago. Wondered if anyone may offer a solution to right this path.

enter image description here

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    The beam was already cut and you just adjusted the plumbing. I doubt that anything needs to be done but sistering a board on the other side of the cut will provide more support for the shower pan and add strength to the old beam.
    – Ed Beal
    Oct 11, 2016 at 0:49
  • To add to @EdBeal 's suggestion, given that there doesn't appear to be a lot of free space, perhaps a steel plate rather than wood as the "sister" support. Oct 11, 2016 at 15:17
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    I doubt any of the pictured floor joists (FJ) are beams. Beams transfer loads to vertical support members and are the things upon which FJs rest. The pictured, notched FJ should be sistered with a FJ that runs the entire length of the one notched (to rest on the beams or rim joists that support the one notched). Nov 27, 2016 at 22:24

1 Answer 1


Considering you are probably putting the shower on top of this, you should definitely sister on a joist as large as is feasible. Be sure it runs as far as possible, hopefully to the bearing points (walls, etc.).

I am assuming the joist in question is the one at the bottom of the picture. If not, the advice should still apply.

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