[joelowrider]

Is 1/4 over 3/4 partical board good enough to tile over

[joecaption]

Patical board is not a sutable subfloor for any flooring. Doubley so with tile.
It soaks up moisture like a sponge, falls apart like oat meal if it gets damp once. Expands and contracts will not hold nails or screws.
Remove and replace with Advantec 3/4 T & G then a layer of at least 3/8 underlayment rated plywood over that, then the 1/4" tile board.

[oh'mike]

Odd that you would have particle board for a sub floor---are you looking at OSB (oriented strand board)

Which is acceptable under your backer---

Use google images and see what OSB looks like and get back to us.---Mike---

[JazMan]

Lots of people get particle board and OSB confused, please double check.

If it's particle board it should be removed, otherwise you're ok. Every backer board manufacturer says installing their board over 3/4" ply or OSB is just fine. Some even claim 5/8" is ok. I believe I've also seen 5/8 on 19.2 and 24" o.c. joists too.

The only time you have to have two layers of subfloor is if installing natural stone. Of course the more the better regardless whether it's necessary or not.

And yes, 1/4" is for floors, none of them add strength to the floor.

Jaz

[joelowrider]

No it is particle board for sure I know what it is the floor is its over top to 1 inch boards I have pulled it up in the bathrooms before tile I was trying to avoid it Because the kithcen is 300 sq ft the board crubles when you pull it up its a pain

[JazMan]

Well.....sorry to hear that. Next step is to take the junk to the curb.

If you have 1"x plank subfloor in perfect condition, you may be able to go with 1/2" underlayment instead of 3/4"

Jaz

[oh'mike]

The you must remove the particle board---that material is not good for anything in a house--

Replace with a good 3/4" bc exposure 1 plywood--