Latest Discussions : Flooring & Stairs


05:41AM | 01/14/06
Member Since: 01/13/06
2 lifetime posts
I am rebuilding a screened porch and turning it into a four season porch/sunroom. The floor is a 4 inch poured concrete slab over an unheated utility room. The house was built in the late fifties and the slab floor has been painted at least once. I can tell you from working in this area that the paint/coating does seem to be well adhered to the concrete. I was going to have a professional install the tile floor but was told that they could not warrant the job based on the fact that the tile would be applied over a painted slab. My question is.......What would be the proper way to proceed?




03:42PM | 01/14/06
Member Since: 07/03/05
283 lifetime posts
The tile installer is right. Even though nothing may happen, nobody has a crystal ball and the track record of tile over painted floors is not great so he is basing his decision on historical data.

You could do two things.

1. Check around for some membranes that could be put over the paint. I dont know of any offhand but maybe Noble Company or Schluter which makes Ditra. The tile could then be set to the membrane with thinset.

2.Grind the paint off. Some of the more industrial type rental ceneters will rent you a machine that looks like a floor buffing machine. They will sell you the bricks that mount to the underside and grind away everything, plus make the floor more even by removing any high spots. A shop vac hooks up to the outflow port to gather the unbelievable amount of dust that it will create.


05:48PM | 01/14/06
Member Since: 04/25/05
1915 lifetime posts
Protecto wrap makes a peal and stick anti-fracture menbrane that might work.

I ran into another company that has a glue down membrane (vs the thinset type). But I forgot the name.

Also you can get the concrete scrafied.

Shot blasting is one process.

Probably done by company that do concrete resurfacing and restoration work.


10:52PM | 01/15/06
Member Since: 01/13/06
2 lifetime posts
My understanding is that there may be a problem down the road with the bond between the paint and the concrete. I am considering laying hardie backer board down over the painted concrete and attaching it using mechanical fasteners. How does this approach sound?


12:44PM | 01/16/06
Member Since: 07/03/05
283 lifetime posts
Not a good idea. The Hardi is designed to be nailed or screwed down over a wood subfloor system. You also put thinset under it to fill in the voids between the wood layer and the cement board. The Hardi gets nailed or screwed at 6" intervals around the perimeter and 8" intervals in the body of the board. Thats a lot of screws ($$$) to set into a concrete floor, about 60+ a board. The thinset under the board is IMPERATIVE and the Tapcons or Walldogs ($$$) must be set so the head is flush with the surface of the board unless you want to pour self leveling cement over the whole floor ($$$). After all that the cost of a grinding machine for the day will be under $200, but you will need help to transport it, they are very heavy.


01:38AM | 04/16/16
Grinders really don't help remove paint which has need intentionally rolled on. Ocassionally you might be successful in cleaning up some drops or two. The stones for the grinder are expensive, if you have a large area you will need multiple sets. And as I mentioned before, it won't work anyway.

The.paint was sucked into the porus cement. You may try using chemicals to remove it. You might get lucky and find out that the slab was sealed and then painted at a later date. You can float a plywood floor, then screw your hardi to that, however it is quite expensive (6 mil membrane under plywood and under your greenboard) 2 layers of half inch plywood (not osb) screw through the green board into the plywood short screws).

You now have somthing on the order of an inch and a half of subfloor ready for thinset and tile.

Probably going to cost you about 5.5 - 7.5 bucks a square foot.


01:13PM | 04/15/19
Your best bet would be to burn the pain off some how..


11:43AM | 03/15/20
OMG these are all rediculous suggestions. Steam off the paint with a steam mop and rough the concrete up a bit. The tile will be fine. Suggesting another product over the concrete is overkill.


05:29PM | 03/26/20
What I am doing with a similar situation is using a 3/4 inch chisel point in my rotary hammer drill and cutting grooves through the paint into the concrete about every 2 to 3 inches. Took me about 5 hours to prep about 100 sq feet for tile. Did not remove the paint between grooves unless it was loose. Used a long scraper shovel to remove the puckered paint arount the grooves. Dust did not fly everywhere but a dusk mask and earplugs were essential. Chisel left a groove about 1/4 inch wide by about 1/8" deep. Should bond the 12" tile to the floor real well as it will have both a mechanical and chemical bond in the groove with the thinset to the freshly exposed concete in the groove. I suppose you could achieve the same result by drilling shallow holes ever couple of inches but I found
using the chisel bit to groove easy enough.


07:18AM | 06/15/21
Door Lock Fitting in London


07:55PM | 01/14/22
Diamond grind off coating with PCD and 30/40 metal bond diamonds.
use a grinder with at least 400 pound down pressure or more.

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