Underlayment for floor in prep for porcelain tile

[redbeast]

Just wondering for those who have installed ceramic/porcelain tile in the bathrooms what underlayment you used.

Our existing bathrooms have lino and then K3 board (particle board underneath.

I've heard many different ways and most popular is to remove the lino and K3 board and screw down plywood and then thinset and tile.

Then I've been told by some tile shops that wonderboard is fine on top of your subfloor after K3 has been removed. Again, thinset over wonderboard and then tile.

How thick of a substrate do I need before installing tile? 3/8 or 1/2" ?

Thanks

[ianmcc]

I have family who are tile setters, and I have had them do several floors for me.
If you remove the K3 then use ¾" plywood.
If the lino is in good shape (not coming up anywhere) you can screw the lino down with drywall screws-one every 6", then sand the lino to scuff it up.

I think you need to add something to the thinset like an epoxy to help it adhere,
although that is the econo way to go. Shouldn't be a problem on a small floor like a bathroom.


I should also add they are Dutch and I am Scottish so birds fly over my house going "cheep cheep"!

[black_shadow_18]

total subfloor thickness should be 1 1/8 inches thick. (as seen on the side of mortar mixing bags. I have also heard wonderboard is BETTER to tile over as the thinset is supposed to adhere better, but it is substantially more expensive than plywood which is used in almost every new home and they dont seem to have any issues...


oh ya, the particle board HAS to go. it has too much flex to it and you will be fixxing cracked grout joints regularly.

[PureDeXteritY]

Originally posted by ianmcc

If the lino is in good shape (not coming up anywhere) you can screw the lino down with drywall screws-one every 6", then sand the lino to scuff it up.

I'd go with this suggestion
Lino is not that difficult to remove from the K3, but the K3 will be bitch ass to remove from the subfloor.
It's glued down and stapled to the subfloor, when you try to remove it it breaks up so you have to remove small chunks at a time.

I usually just suggest laying tile on top of the lino when people want to switch from lino to tile.