Using ditra on uneven pier and beam floor

manineedhelp · 10-13-2012, 01:52 PM

This is my 1st post here, so plz forgive my ignorance about most everything. I'm going to attempt to install 13" porceline tile in a very small bathroom which is pier and beam construction. The tiling area is approx 30 sq ft. ( 5' x 6' ). the original wood flooring is still there... it is 1" tongue and groove. i am planning on using ditra as an undferlayment(?) on top of this tongue and groove. At some time in the past ( the house was built in 1942 ) there was severe water damage in this bathroom around the toilet and bathroom sink area. I replaced the damaged portion of the floor with 1" x 4"'s I screwed into the beams ( joists?). There is a slight unevenness where the new replacement flooring I put in transitions to the older tongue and groove, right in front of ( approx 8" in front of the toilet drain). Will the ditra work as a leveler too in this one small area? I hope I am being clear enough with my problem. In very blunt terms, when I use the ditra installed as the directions tell me to, and after viewing numerous schluter videos and you tube videos, is everything going to be okay? I've never tiled before. Plz help !!

JazMan · 10-13-2012, 02:31 PM

Hi,

First of all I'll assume that when you say t&g you mean planks. You can not install Ditra or any other backer over planks. You need plywood, probably 1/2" or thicker. But, first fix the hump some how.

Jaz

manineedhelp · 10-13-2012, 02:46 PM

Thanks for the quick answer. If I use 1/4" concrete board ontop of the plank flooring, will that be sufficient?

JazMan · 10-13-2012, 08:42 PM

Please re-read my answer again.

Quote:

You can not install Ditra or any other backer over planks. You need plywood,

(first, then the backer or Ditra or............)

Jaz

joecaption · 10-13-2012, 08:48 PM

1 X 4's never should have been used as a subfloor. A product like T & G 3/4 Advantec with constrution adhesive on top of the joist, then a layer of 1/2 subfloor rated plywood would have been 100 times more ridgid.
For tile to not crack and also not have the grout fail it has to have 0 movement.

manineedhelp · 10-14-2012, 01:30 PM

I am ripping out the t&g, and replacing with 3/4" plywood. I am going to use wood glue ontop of the joists and then screw the plywood down. Then I am going to use the ditra. Any other suggestions?

Daniel Holzman · 10-14-2012, 02:49 PM

I don't think you fully understood the comments. It is common practice to install 3/4 inch plywood above plank floor, every house in my neighborhood (mine included) is done that way. If the plank floor (you call it T&G) is OK, you can install plywood over it, then install Ditra over that, then tile. What you cannot do is install Ditra over plank directly.

I did my kitchen with Ditra over 5/8 plywood over 3/4 inch diagonal planks. You can level the floor with self leveling compound (SLC), the use of which has been discussed repeatedly on this forum.

As to whether 3/4 plywood directly over joists is adequately stiff, that depends on the type of tile you are installing, and the size of the tile.

manineedhelp · 10-14-2012, 05:05 PM

The reasoning for ripping out the planks is so I will not have such a high lip transitioning into the hallway, which is also the tongue and groove plank. I am placing down 13" x 13" porcelin tiles. The tiled floor area is approx 30 sq ft. Very small.

JazMan · 10-14-2012, 08:36 PM

A single 3/4" t&g ply or OSB subfloor properly glued & screwed to the joists is plenty stiff enough as a base in a ceramic tile installation using Ditra or concrete backer. Don't forget you have to install blocking under all unsupported edges between the joists where the planks were removed.

Jaz

JetSwet · 10-14-2012, 09:26 PM

Quote:

Originally Posted by manineedhelp

I am ripping out the t&g, and replacing with 3/4" plywood. I am going to use wood glue ontop of the joists and then screw the plywood down. Then I am going to use the ditra. Any other suggestions?

Yes add 1/2" ply on the 3/4" unless your joists aren't less then 12" and 16" OC, but I doubt it since its pier and beam. And yes get rid of the planks.

JazMan · 10-14-2012, 10:07 PM

Good point Jet,

That's right we never got to how the framing was built. Need to know all that stuff. Type and size of beams & joists, spacing etc.

Jaz