120 Year Old Bathroom Subfloor Mess

[RebeccaS]

Hello All! I am DIYing the upstairs bathroom in my 120 year old rowhouse and think I've hit an issue above my pay grade (which is...free). Upon removing the tile, I found a concrete slab that slopes from about 1" (at the door) to 2" (back of bathroom) thick. It was severely cracked around the bathtub, toilet and door, which I've removed. The rest of the concrete seems pretty solid. Under that is a combination of hardwood and plywood subfloor. I'm guessing the hardwood may be the original subfloor from the late 1800s. It looks ancient but solid. The plywood is a mess, and has to come up. I've attached pictures. I'm definitely getting help on this, but had a few initial questions. Worth keeping in mind this will be an investment property, so I'm going for durability, but nothing too fancy.

1. Should I just remove all of the concrete, even where it seems pretty solid? Or should I leave well enough alone and just pour new concrete where necessary?

2. If I remove everything, should I pour a new concrete slab or go with OSB/enhanced plywood and backerboard? I'm worried a 2" concrete slab is adding a lot of unnecessary weight to this old house. However, since there's an almost 1" difference between front and back, maybe self-leveling concrete is easiest. Alternately, is a thin layer of concrete to level, topped with OSB and backerboard the best option? I need to get back up to the current height to keep it level with the other rooms and the plumbing fixtures.

Many thanks in advance for your help on what I'm sure is the first of many questions to come. Any advice at all would be so greatly appreciated!

Thanks!
Rebecca

 

[Nick]

Remove everything down to the hardwood .. If the floor is flat you can go with underlayment .. A lot cheaper ..
You want Durable and cheap .. Pick one !! I would go with Cortec , You won't be replacing it every year ..

 

[RebeccaS]

Amazing! Thank you so much, Nick. Really glad I found this forum!

Unfortunately, nothing is level in this old house. A lot of settling in 120 years. I’ve got about a one-inch slope over 8 ft from the door to the back wall. Should I level this out with a concrete SLU product topped with backerboard? This house is gonna be a project!

 

[Nick]

If you are going to pour concrete , You shouldn't need backer board .. I would wait for E, or Don to reply .. Those two guys do that every day..

I see you are from my old stomping grounds ..

 

[RebeccaS]

Are you from New York?!? I've been here for ten years. Finally found this old rowhouse in Bed Stuy. It's a pretty great spot!

Look forward to hearing from Don or E! I'm tearing up the rest of the cement in the morning. I'll post more pics if anything new turns up (hopefully not, but ya never know...). Wish me luck! R

 

[Nick]

Good Luck .. From the Island , But i sanded a lot of bowling alleys there ..