2

After removing an old bathroom floor in a historic structure, in order to sister joists for a level surface to install new subfloor, we found that one of the original floor joists was notched, and then cut, by previous owner in order to run drains. We're redoing all of the plumbing, but this is a question about the joist.

How would we fix this? You'll see in my pics that previous owner/worker tried to brace this between two joists with a 2x4. I don't trust it.

How would you fix this the right way?

enter image description here enter image description here

mmathis
  • 8,863
  • 12
  • 42
  • 64
Alexander Munro
  • 23
  • 3

1 Answers1

3

You really need an engineer to give you an answer and sign off on this. But, being this is the internet, here's my $0.02 anyway.

Your best bet is to replace the whole joist if feasible and not to disruptive to the rest of the structure. But it will be very disruptive to the rest of the structure & flooring and probably impossible to get it into those foundation pockets on both sides. So...

I would cut the existing joist back to the middle of that knee wall or 2x4 nearest the foundation wall. Not counting on that structurally, but you need to square off the end of the existing joist and it makes a convenient place to put the end of the new joist while you tie things together. Take off that little bit of 2x4 back near the drain pipe.

Then I would slide a new piece of joist into the pocket in the foundation wall and flush with the end of the existing joist on top of that 2x4.

Then I would sister the joist on both sides with 2x dimensional lumber of the same height as the existing joist from the foundation wall pocket back to at least 2' to 3' past the end of that huge notch. Be generous with construction adhesive, then clamp the whole thing up and put a few bolts through to pull it together and nail it along the length.

CoAstroGeek
  • 2,338
  • 1
  • 14
  • 21
  • 1
    All that ^^^. But do I see a sliver of light at the next joist pocket? Could you pop a bit of siding off and sneak a new (long) joist from the outside? – Aloysius Defenestrate Jan 05 '17 at 17:15
  • Good eye - I didn't notice that. Opens up options for replacing the whole joist. – CoAstroGeek Jan 05 '17 at 17:16
  • Ah. Sliver of light is the end of a carriage bolt from the new wood we've sistered in. – Alexander Munro Jan 05 '17 at 17:57
  • Ok - obvious now that you mention it. – CoAstroGeek Jan 05 '17 at 22:19
  • Thank you for the detailed answer, CoAstroGeek. Would you use an angle grinder to expand that notch in foundation wall in order to accommodate for the new lumber now that we're using one piece on either side? – Alexander Munro Jan 06 '17 at 23:45
  • No - you're fine with just the original single wide joist in the pocket. The sister joists are just there to tie everything together across the notch and discontinuities to make it act like the original joist structurally. A single joist was enough at that pocket initially, so it will be now as well.. – CoAstroGeek Jan 07 '17 at 00:13
  • Got it. The existing wood actual size is 1 and 7/8ths" by 11" so I think I'm going to call a lumber company to see if they can get me a cut that size. The reason I pulled out the floor, was to sister existing joists to give a new level flat surface. Once I add this new wood, can I sister on top of it again so that I have a level surface to lay plywood? – Alexander Munro Jan 08 '17 at 17:43
  • I would just use a 2x12 - actual size will be 1.5x11.5 I would do whatever you need to level your floor with these two joists all at the same time. – CoAstroGeek Jan 09 '17 at 02:30