Is this good enough? Removing thinset from concrete

[jdavis@openactive.org]

Hello!

First time poster, long time lurker. I am finally trying to remodel a bathroom in the basement. I have removed the tile and am now trying to remove the old thinset. I plan on putting new tile on the floor once it's all preped. Do I need to remove everything down to the old concrete? Is this good enough?



This is a small patch I have removed. I tried to remove more with the demo hammer but I started gouging into the concrete so decided I should stop and ask for advice.

Thanks!

[Lou_MA]

I’d want to remove all those old thinset ridges and get back to the slab.

Rent a 7” grinder and cup wheel, and put up dust containment system or other form of dust control.

[jdavis@openactive.org]

Thanks Lou. I have all that on the way now. Set me back $315 for the 7" Makita Grinder, cup wheel, and dust shroud.

[Davy]

Welcome, Jason. That should do the trick if you have a good Shop Vac. A Dust Deputy would also help but may not be worth buying if your floor is small. I have heard about making your own Dust Deputy type dust catcher.

[jdavis@openactive.org]

The grinder and cup wheel got the job done. I had a hard time with the dust collecting. I changed the filters a few times and was constantly having to clean the filter. Is that pretty typical? I imagine grinding a large area with a dust collector would take a lot of work to keep the vacuum functioning. When the filter was not plugged the dust collecting worked fairly well.

[Lou_MA]

Yes, that’s typical. Clean the filter and it gets clogged again really quickly.

If you were to do this again, the dust deputy would help a lot.

[jdavis@openactive.org]

In hindsight I should 100% have tried that out.

[jdavis@openactive.org]

Hello!

What is the best way to trim an 1/8" off cement board? If this were drywall I would use a rasp. I tried that on cement board and it has little to no effect. Any suggestions? Thanks!

[Rigo]

Hi Jason, just a heads up. The pros are gonna ask ya why you wanna trim it. What size and brand of cement board you are working with and where you plan on installing it/them.

[cx]

And whether it's the same project where he's cleaning the thinset mortar off his concrete slab, Rigo.

[Rigo]

Yes sir, forgot that one.

[jdavis@openactive.org]

Ah sorry. I'm a total newb here. Thanks for the heads up.

I'm working with 1/2" PermaBase. I'm installing it in my new shower. I have cut a few pieces just slightly too big and wondering if there is an easy way to trim it up a bit.

@CX Yes! Still plugging a way at the same remodel. Took me ages to get the drain moved, floor leveled, and the new pan installed. Finally getting around to hanging the wallboard!

Few images to update the project:

[cx]

A moderator can give your project thread a more generic title any time you'd like to suggest one.

You're gonna want a little room at the edges of those panels, Jason, so if they're already tight, you'll likely wanna remove more like 1/4" of material. You can do that with a circular saw and masonry blade, angle grinder with masonry or diamond blade, or similar. Will be exceeding dusty and you wanna do it outside and wear the appropriate PPE. You could also try removing that edge with a utility knife and many passes. With the utmost of care, please.

Please tell me you didn't leave that plywood on top of your slab under whatever the green thing is you're using as a shower floor.

My opinion; worth price charged.

[jdavis@openactive.org]

Thanks CX. Noted on the 1/4" of space. I'll try my angle grinder tomorrow.

I did remove that plywood. I was using it as a jig to get the drain at the right height and exact center. Here is a picture after the plywood, but before the leveling compound.

[cx]

I feel better already.