[DiYerInNY]

I previously created a thread with an issue of my bathroom being half concrete and half wood. Turns out it was wrong and it was only 2" thick of pour concrete of which I removed. After removing the poured concrete, I noticed the rotten joist. I think whoever worked on this before, poured to concrete to address the issue with the rotten joist.

I wanted to originally replace the joist ( the joist measures 4x8x10, 16" OC, 10" Span, however I am having a hard time fitting the wood through. There are bunch of air duct vents and electrical work in the way underneath, so I can only get about 5-6' feet in before I hit something.

Is there any other way I can remove the rotten joist and make a new support some how? Would cutting the 4x8x10 joist in half and sistering it be ok?

Pic of my bathroom floor

https://imgur.com/a/GTHWfyc

* Don't mind the random 2x4 in the middle, I was just seeing if it would go in cleanly

 

[Nealtw]

How bad is the old one ?
A 2 piece joist isn't the way to go until you have nothing else.

 

[DiYerInNY]

How bad is the old one ?
A 2 piece joist isn't the way to go until you have nothing else.

I'm not quite sure what made the original joist that way, meaning is it water damage, some sort of bug damage?

https://imgur.com/a/yaaMnUw

But it is a 4x8x12 joist of which 5-6 feet of it is damaged, IMO.

And what did you mean by 2 piece joist isn't the way to go?

I wanted to cut off the rotten piece of the original joist replace it with a new section and sister it with an additional joist running the full span of the original joist. Or would I be better off with a header joist or some sort?

 

[Nealtw]

I'm not quite sure what made the original joist that way, meaning is it water damage, some sort of bug damage?

https://imgur.com/a/yaaMnUw

But it is a 4x8x12 joist of which 5-6 feet of it is damaged, IMO.

And what did you mean by 2 piece joist isn't the way to go?

I wanted to cut off the rotten piece of the original joist replace it with a new section and sister it with an additional joist running the full span of the original joist. Or would I be better off with a header joist or some sort?

Poke at it with an awl or sharp screw driver and guess at what % is still good. Is it just the top or are there sections that it is all bad?

How much would be left if you carved away all the bad?

 

[DiYerInNY]

Poke at it with an awl or sharp screw driver and guess at what % is still good. Is it just the top or are there sections that it is all bad?

How much would be left if you carved away all the bad?

Its mostly just the top portion and the bottom half seems to be solid. dont see any section where its all bad but kinda hard to tell

 

[Nealtw]

Its mostly just the top portion and the bottom half seems to be solid. dont see any section where its all bad but kinda hard to tell

Not sure if you have insects or fungus like dry rot. I would carve away as much of the bad as i could and then paint everything with a copper treatment like the end cut treatment for treated lumber and then make a decision on what it needs for strength and bring it back up to height.

 

[DiYerInNY]

Not sure if you have insects or fungus like dry rot. I would carve away as much of the bad as i could and then paint everything with a copper treatment like the end cut treatment for treated lumber and then make a decision on what it needs for strength and bring it back up to height.

excuse me for being ignorant but why even bother to salvage it? why not just cut off the rotten portion and throw in a new section ?

 

[Nealtw]

excuse me for being ignorant but why even bother to salvage it? why not just cut off the rotten portion and throw in a new section ?

Because right now it might be 40, 50 or 60% as strong as it was and you can add back strength by adding to it . If you cut it your repair is totally depending on nails or screws. Others may disagree with me but that is the way I see it.

 

[de-nagorg]

In my "neck of the woods", a 4X8 X12 is a beam.

I too would just shave off what seems damaged, just to see how far it is damaged, and if not much, do the Copper sulfide treatment to stop anymore rotting.

And then add a sister, spanning at least 2 bays to either side of the removed part.

ED

 

[DiYerInNY]

excuse me for being ignorant but why even bother to salvage it? why not just cut off the rotten portion and throw in a new section ?

Because right now it might be 40, 50 or 60% as strong as it was and you can add back strength by adding to it . If you cut it your repair is totally depending on nails or screws. Others may disagree with me but that is the way I see it.

Got it, thanks for the explanation.

How do you suggest I add strength back to it ? Sister joist? If so, full length span like the original joist?

 

[Nealtw]

Got it, thanks for the explanation.

How do you suggest I add strength back to it ? Sister joist? If so, full length span like the original joist?

can you get a full length in there?
A taller joist would be best. you could block in the spaces beside the old joist on the supporting walls and use hangers to use a 2x8 or 2x10 from wall to wall.

 

[DiYerInNY]

Got it, thanks for the explanation.

How do you suggest I add strength back to it ? Sister joist? If so, full length span like the original joist?

can you get a full length in there?
A taller joist would be best. you could block in the spaces beside the old joist on the supporting walls and use hangers to use a 2x8 or 2x10 from wall to wall.

I actually can’t, well not 100% sure, still investigating how I can try and squeeze in a full length. As of right now, the answer would be no.

This wood was covered with concrete/mortar bed, and it’s only exposed now because I removed it all and vacuum. Would I still need to paint it with the copper green treatment ?

 

[Nealtw]

I actually can’t, well not 100% sure, still investigating how I can try and squeeze in a full length. As of right now, the answer would be no.

This wood was covered with concrete/mortar bed, and it’s only exposed now because I removed it all and vacuum. Would I still need to paint it with the copper green treatment ?

If that is rot, it is fungus, anything that has a water stain is suspect, you want to kill it and copper will do that. Engineers and city inspectors here call for it anytime we are making repairs like this.

 

[DiYerInNY]

If that is rot, it is fungus, anything that has a water stain is suspect, you want to kill it and copper will do that. Engineers and city inspectors here call for it anytime we are making repairs like this.

Once again, thanks for the explanation !

In the event that I can't fit a full length in, what do you suggest my next step be?

Also about the blocking, did you mean to add blocking to the adjacent joists to the rotten joist?

Why add hangers, and why not just nail them directly to the joists?

 

[Nealtw]

Once again, thanks for the explanation !

In the event that I can't fit a full length in, what do you suggest my next step be?

Also about the blocking, did you mean to add blocking to the adjacent joists to the rotten joist?

Why add hangers, and why not just nail them directly to the joists?

Blocking between the old joists on top of the lower walls for a flat surface to nail the hangers to.



Any time there is a change in the size you are tking a chance it will split there.

They uses to notch the beam and joist together and they split right at the notch. so when ever we can we support the ends to prevent that.

 

[DiYerInNY]

Blocking between the old joists on top of the lower walls for a flat surface to nail the hangers to.



Any time there is a change in the size you are tking a chance it will split there.

They uses to notch the beam and joist together and they split right at the notch. so when ever we can we support the ends to prevent that.

Ah, I actually can't install hangers for the joists to the lower walls, there's only enough space for a 2x8/4x8 to fit it into. Won't be able to fit like a 2x10 in there.

https://imgur.com/a/0bjEakP

Any advice if I can't fit a full length joist?

 

[Nealtw]

Ah, I actually can't install hangers for the joists to the lower walls, there's only enough space for a 2x8/4x8 to fit it into. Won't be able to fit like a 2x10 in there.

https://imgur.com/a/0bjEakP

Any advice if I can't fit a full length joist?

Solid block between joist on top of the wall

 

[Nealtw]

2x10 sister butted into wall and block above the wall with hanger nailed to block.

 

[DiYerInNY]

2x10 sister butted into wall and block above the wall with hanger nailed to block.

Thanks for taking the time to draw it out for me, but as much as i would want to add in a 2x10, there are 2 airducts that are butted underneath the original joists so its hard for me go a bigger size.

Even if I could remove the airducts, which i couldn't, there is only enough opening for a x8 wood to fit through. The other end of the original joists are resting on a steel beam, which is enough opening for x8 wood.

Unless you're telling me to block some where in the middle with a joist hanger too?

 

[Nealtw]

Thanks for taking the time to draw it out for me, but as much as i would want to add in a 2x10, there are 2 airducts that are butted underneath the original joists so its hard for me go a bigger size.

Even if I could remove the airducts, which i couldn't, there is only enough opening for a x8 wood to fit through. The other end of the original joists are resting on a steel beam, which is enough opening for x8 wood.

Unless you're telling me to block some where in the middle with a joist hanger too?

What is the room below can you support to the floor or add a beam going the other way under your end.
If you have to settle for an 8" I guess you just hope for the best.