Basement Bathroom Floor Finish height
We’re in the process of putting a bathroom in our completely unfinished basement. Concrete slab is old (no poly) but in good condition of our 1920s house in Minneapolis. I’m struggling to determine the right way to dial in floor heights. We currently have the floor trenched for drainage/sewer plumbing.
For the bathroom, I’m planning the following build: Slab – thinset – Cerazorb (thermal break – 6mm) – thinset – Ditra Heat (6mm) – thinset – quarry tile (12mm). Total stack is ~1 3/8″
I’m considering three options:
A. Start basement floor from current slab level, have a 1 3/8″ floor difference to account for at bathroom threshold. Pro: Easy to complete. Con: This seems like too much to transition well.
B. Break up the rest of the concrete bathroom and pour new concrete to be below the rest of the basement. Pro: No transition at threshold. Cons: more digging, can’t finish basement floor at a later date.
C. Plan for a finished floor in the rest of the basement (foam and double layer of plywood floated = 2″) and build bathroom floor to match. Pro: Easy to match transitions. Con: More cost, did not have plans to finish basement floor.
There are some other options to consider: use a thinner floor tile, Use SLC to bring up the rest of the basement floor (or at least max at bathroom and sloping away).
I want to lean to C, just because it covers all the bases. However, we had not planned to finish our basement floors, so adding that into our bathroom project is hard to grasp, but might be the right choice.
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Replies
I'd also lean towards your final choice. You wouldn't need to cover the plywood right away, or you could cover with a temporary product like area rugs.
A couple other things to consider, when adding height to the basement floor, you will be changing the first step on the stairs going to the upper levels. You may also need to rebuild the stairs. Another concern would be vapor moving through the slab. You'll probably want to add a vapor retarder to the concrete before installing the foam and plywood. I'd lean towards a roll-on product like RedGard, but there other methods that would also work.
Good luck on your project,
Randy
Why add any finishes to the floor of the bathroom if you are not finishing the rest of the basement? What about a sealant, paint, or sheet vinyl over the whole basement floor?
I with Krackadile. Don't tile till you are ready to finish the basement. If the basement is like anything around here, with the trenching lot of the concrete is already out, I would pour a new level slab for washroom only. This will make tiling much easier and lets you use larger format tiles.
If you want some temporary flooring, get a couple of boxes of vinyl click and put it down. Vinyl click straight on the old slab is pretty common flor basement flooring around me as it can follow a bit of slope.
I appreciate everyone's thoughts. We currently only have 1 bathroom, so adding a second (with shower) will be a welcome convenience.
It seems that finishing the flooring over the whole basement is the best solution, which I tend to agree with. If I have a plan for finishing the rest of the basement, I can easily continue with the bathroom project, and build the bathroom floor height to match the rest of the basement when completed. This will also make it easier to level the bathroom floor area for tile as Akos suggested.
I understand the consideration for the stairs as well. The stairs are already in fair condition (covered in bright blue paint), and so replacing them is as good a choice as repainting them, or replacing the treads.
Any other advice you can suggest that I'm not considering?