Repairing a Rotted Wall or Floor Joist

I’m rebuilding a house after tearing it down to the bare studs. I found a few spots where (in the bathroom) the floor joist had gotten soaked through and rotted. This is how I fixed them. The house is over a hundred years old, and had surprisingly little rot. This house originally did not HAVE a bathroom attached to it, and the previous owners did a very slapdash job on adding one in. So not only am I dealing with the wear and tear of time, but also shoddy workmanship. Making it so that this house lasts another hundred years is my goal. :)

Materials Used:
2 x 6 board. size and length  varies
quick setting wood glue
3 1/2"  wood screws (length can vary depending on wood size)

Tools Used:
flat head screwdriver
circular saw
electric/ battery operated driver
3ft. level
speed square
elbow grease and patience

Step 1: Find the Nasty Spot

 Find the rotten spots. This can be easy or difficult. You can poke the questionable board with a screwdriver and see if there’s any give to the board, and you can also do a visual inspection: a darker spot on the board can be a sign of rot.

Step 2: Get Rid of the Rotten Spot

 Cut the rotten spot out. This part can be a little hard, depending on what wood you are working with. Pressure treated stuff won’t let the water flow through the wood as well as straight regular wood. You want to cut about 6 inches past where the rot ends, just to make sure no more moisture will get through.  Once that’s done, your spot will look like the picture above. The floor joist was also where a wall is, so there were two joists butted together. MAKE SURE that the other board is not rotted as well! I checked all four sides of the other joist to make sure there was no rot.

Step 3: Put in the New Board

   Now you got the rot out. Now what?  Really simple: ya put new wood in!!  I used the same size board (2x6) and cut out one piece to replace the rotted piece. Put the new piece of wood in, using screws that are twice as long as the thickness of the new wood. (I used 3 ½ “ screws in this case) I also put a nice little bit of glue between the new piece and the other joist for more gripping strength. The screw pattern I used was a high/low 8” between the screws, meaning the first one I put in towards the top of the board, the next one down I put towards the low end of the board.  This is a floor joist, so make sure you stay LEVEL  when putting it in. then I went to the other side of the double floor joist and did the same thing from the opposite end of the piece I put in. 

Step 4: Laying the Bottom Stud

Once that was all in, I also put a floor stud in to attach the wall studs to. This is a regular 2x4, measured and cut to replace the part I cut out. Again, I used a zigzag pattern to secure it to the new joist, making sure the screws penetrated both the old and new joist pieces.

Step 5: Installing the Vertical Studs

Once that’s down, you put the wall studs up, making sure to check for both level AND square! This can be done by using both a level (on two sequential sides of the stud) and a speed square (on two opposite sides  of the stud) this will make installing the wall outer covering, whether it be drywall, or lathe, so much easier.

 Once that’s in, sit back and gloat about the fact that contractors can charge upwards of $1000 to do something you just did for the price of the wood and screws and glue.



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    7 Discussions


    Good job! I'm renovating a 60+ year old house and it has numerous foundation problems - including rot.
    As added "insurance" you could use Simpson's metal joint hangers to your floor joist, just to give the flooring a little more support. (I'm not good at toe-nailing 2x's).
    Again, great job. I know you have put in a LOT OF WORK to get to this point.


    Reply 7 years ago on Introduction

    thanks for your response!! i will be posting up a few more as I come up on them. next up: either putting up a new wall or creating closets! I'll let the community decide on this one by responses!!

    You did an awesome job, I love having you as my General Contractor! :)
    I cannot WAIT to see the bathroom once it is finished!