How would you fill/seal this hole?

[Rod N]

Hi Gents,

Remodeling the basement and found some decay around the baseboard.

Remove all the rotted wood and found a piece of forming was left in the floor and rotted everything.

What would you use to fill/seal this hole after I pull out as much of the wood (black part in the corner) as possible?

Thanks
Rod

 

[Rod N]

Cement? Epoxy? Can o foam?

 

[four.cycle]

You would need to remove all of the rotten material first.

I would:
- Remove all of the rotted wood.
- Liberally apply a copper napthenate solution to the surrounding wood.
- Allow the copper napthenate solution to dry at least 48 hours.
- Patch the void with "Fix-it-All", and I'd mix up the first few batches with Marine Spar Varnish, not water. (You don't want to apply "Fix-it-All" in layers that are too thick - you might have to apply successive layers.)(Mixing the "Fix-it-All" with Marine Spar Varnish instead of water makes it as hard as rock, and relatively bulletproof, but virtually impossible to sand, so make sure you only put it where you want it.)
- Allow the "Fix-it-All" to cure at least 48 hours.
- Apply a top coat of patching compound (either "Fix-it-All" or Spackle) to match the adjoining surfaces.
- Prime, texture, and paint.

Kind of an old-school, very time consuming way of doing it. I've fixed a few rotten walls this way.
Personally I don't think that "foam-in-a-can" stuff is worth a damn, and it just makes a hell of a mess everywhere. Just my two cents.

 

[Rod N]

^^ I appreciate the advice.
Maybe I wasn't clear. The hole, about 3" x 8" x as deep as I can dig out the rotten form is surrounded by concrete. Both walls and floor are poured concrete.
You will never see the fix because it will be behind the walls after I replace the studs that I cut out.

 

[EOC_Jason]

Once you get the rotted wood out, might as well just mix up a small batch of concrete to fill it... It would be okay if it's more on the liquidy side, it's not going to be structural, you just want it to fill a hole.

 

[73fxe]

Clean out all rotted wood. Use hydraulic cement, let dry for a few hours and patch the drywall.

 

[lakelandcat]

Once you get the rotted wood out, might as well just mix up a small batch of concrete to fill it... It would be okay if it's more on the liquidy side, it's not going to be structural, you just want it to fill a hole.

I agree, but my question is why did the form rot? Do you have moisture? If so now is the time to find /fix the leak. Look for mold and remove also.

 

[LX-Markham]

Once you get the rotted wood out, might as well just mix up a small batch of concrete to fill it...

I'd use hydraulic cement so it doesn't shrink.

https://www.homedepot.ca/en/home/p.hydraulic-water-stop-cement-9kg.1000149564.html

edit: oops, didn't notice 73fxe beat me to the punch.
I agree with what 73fxe recommended

 

[Dirtydan69]

Clean out all rotted wood. Use hydraulic cement, let dry for a few hours and patch the drywall.

This

 

[four.cycle]

Maybe I wasn't clear. The hole, about 3" x 8" x as deep as I can dig out the rotten form is surrounded by concrete. Both walls and floor are poured concrete.

Okay... I didn't get that from the photo image.
Different game plan would be in order in that case.
My method above was used on wood-framed walls where the rot was in the studs and the toeplate. Method was described to me by a senior counterman at Alki Lumber in 1988 when I pulled a rotten shower stall out of an apartment.

Concrete - you're working with a different animal there. I'll have to defer to the advice of the guy recommending the hydraulic cement.

 

[Rod N]

Thank guys.
My first thought was hydraulic cement too, but figured I ask in case there was a better way.
My theory is this form is showing on the outside of the house (below grade) and has slowly sucked up moisture over 40 years. Talk about shoddy workmanship. Lucky it stops about 8" into the house or I'd pulling studs even farther.
The wall and floor is nice and dry, so I think I got off easy finding it was this.