[DIYNewbieDD]

Good morning all.
My wife and I are remodeling our 1950s bathroom. After removing the tile wainscoting and 2 layers of drywall, we are left with a 1.5 - 2.0 inch gap between the mud bed and the studs. We don't want to remove the mud bed.
The mortar bed is appox. 1.5 in deep. What would be the best to fill this gap?
Also, there are 2 floor planks that are loose/broken near one of the supply vests to the adjacent room. The floor is stable, but I'd like to bridge the 2 loose planks with something just in case. Any suggestions?

 

[RickMacKay]

Use more mud! You might want to get some 1/4 durock or wonderboard and screw it good to the old subfloor first, this will ensure a good bond. Then get basic mortar mix, around $5-$6 a bag, and mix it up in 5 gal buckets with a paddle, keep it pretty stiff not too soupy. That's pretty much what was already put down 60 years ago. If there are holes you think the new mud might fall through, staple some building paper over them. On your final application trowel it smooth. Assuming you are installing tile over that, I would tape the joints also with thinset and mesh tape----where the old meets the new. Also, any other cracks in the existing floor. Finally, it might be a good investment to Red Guard the whole floor before setting tile.

As far as the hole goes, cut a piece of 3/4 ply that spans the hole and hopefully catches on the framing. Make it as long as possible. Then run screws through the plywood and into the old subfloor. This will cinch it up tight. Then, screw the new plywood off into the old floor. That should stabilize things.

 

[DIYNewbieDD]

Thank you for the info RickMacRay. How close should we go to the duct with the new mortar when filling the gap? Also, should I just use wood screws?

 

[RickMacKay]

Yes wood screws for sure. Gold "deck" screws if you have them. Because the duct will expand and contract, best to wrap it in something that provides an expansion joint, doesn't need to be more than 1/2 thick at the most. Building paper and tape, loosely wound, will do it. a piece of carpet or padding will work, anything that creates a separation.