Ceramic Tile Advice Forums - John Bridge Ceramic Tile

Welcome to John Bridge / Tile Your World, the friendliest DIY Forum on the Internet


Advertiser Directory
JohnBridge.com Home
Buy John Bridge's Books

Go Back   Ceramic Tile Advice Forums - John Bridge Ceramic Tile > Tile & Stone Forums > Tile Forum/Advice Board

Sponsors


Reply
 
Thread Tools Search this Thread
Old 01-19-2018, 12:10 PM   #1
Cordate
Registered User
 
Join Date: Jan 2018
Location: Minneapolis, MN USA
Posts: 2
Porcelain tile in a kitchen, plank subfloor.

Ok. First, can I say how much I appreciate this forum and all you experts? The more I've read, the more confused I am. Digging through here has cleared up a lot of my questions.

I'm preparing to install porcelain tile in my kitchen. The tiles are 7.875" x 7.875". Current flooring is vinyl tiles over more vinyl over wood floors.

House was built in the 1920s. The joists are 7.25" x 1.5" actual, 16" on center. Not sure of exact species, but some kind of pine. Unsupported span is 10 feet. The subfloor is 3/4" x ~12" actual diagonal plank, NOT tongue-and-groove. In fact, there are 1/4"-1/2" gaps between the planks. The calculator likes these numbers, but the calculator doesn't know about the gaps. The floor is very sturdy, with very little creaking and no feeling of give when I walk or jump on it. (Admittedly, the wood flooring is still in place and providing some support.)

The kitchen is about 10' deep and 5-10' wide (lots of odd shapes). The actual walking area is about 5' x 9'. There are some cabinets that I'm intending to leave in place; they were custom built for the small and odd kitchen, run floor to ceiling, and have been there since the 50s or 60s. I don't even know *how* they would come out, honestly. Everything else will be removed so I can do a proper wall-to-wall installation. About 75 square feet total to be tiled.

I know I need to remove the existing flooring. That part is no problem.

I've seen that subfloor replacement in my situation is recommended, but not strictly necessary. It worries me because the current subfloor runs under the exterior walls of the house. If I remove the planks up to the edges of the kitchen, am I going to cause structural issues? I know about blocking, but I can't access underneath because the sill plate has been spray foamed.

I want to do right by the tile, but I also don't want to cause more issues with my house further down the road.

There are stairs involved, so I'd rather not just pile up new subfloor to compensate. If I can get away with leaving the current plank subfloor and adding 1/2" plywood for underlayment, with Ditra the height will be okay (I can fudge the stairs a bit). If I have to add 3/4" plywood, it starts to get dicey.


So, I guess my questions are, in order:

Given the situation, is it even a good idea to replace my existing subfloor?

Would it make sense to only replace it in the actual walking area? I can easily access all of that from underneath to do the blocking.

If I can keep my subfloor, then can I get away with using 1/2" plywood for underlayment?
__________________
C
Cordate is offline   Reply With Quote
Sponsored Links
Old 01-19-2018, 12:51 PM   #2
Obo2
Registered User
 
Join Date: Dec 2017
Location: Nevada
Posts: 87
From the schluter installation guide.
Floors, Interior - Structural Plank Subfloor

Snip

Requirements
Maximum spacing of joists 24" oc
Double layer of wood floor consisting of:
Minimum structural plank subfloor thickness - 3/4"

Minimum underlayment thickness 15/32", 1/2 nom.

So yes you should be gtg with 1/2 and ditra. Go ahead and download the installation guide and look up overlapping, fastener spacing, type of underlayment, and proper thinsets for under and over ditra. Modified to lay the ditra and unmodified on top.
__________________
Nick
I probably have no idea what I am talking about.

Last edited by Obo2; 01-19-2018 at 01:01 PM.
Obo2 is offline   Reply With Quote
Old 01-20-2018, 10:13 AM   #3
John Bridge
Mudmeister
 
Join Date: Mar 2001
Location: Houston, Texas
Posts: 67,070
Send a message via AIM to John Bridge
Hi C,

I see Nick mentions Schluter, but I didn't see it in your posts. In any case, adding half-inch ply will do it. Screw it to the subfloor planks trying to avoid the joists. Then add a tiling membrane.
John Bridge is offline   Reply With Quote
Old 01-20-2018, 10:55 AM   #4
Obo2
Registered User
 
Join Date: Dec 2017
Location: Nevada
Posts: 87
Quote:
There are stairs involved, so I'd rather not just pile up new subfloor to compensate. If I can get away with leaving the current plank subfloor and adding 1/2" plywood for underlayment, with Ditra the height will be okay (I can fudge the stairs a bit). If I have to add 3/4" plywood, it starts to get dicey.
__________________
Nick
I probably have no idea what I am talking about.
Obo2 is offline   Reply With Quote
Old 01-20-2018, 01:06 PM   #5
Cordate
Registered User
 
Join Date: Jan 2018
Location: Minneapolis, MN USA
Posts: 2
Nick, thanks, I did see those specs on the Schluter PDF but I wasn't sure what "structural" meant. I also saw somewhere that Schluter is assuming t&g plank subfloor, and mine is not t&g.

John, thank you!

Really appreciate the assurances from you both. I feel comfortable going forward with the installation now.
__________________
C
Cordate is offline   Reply With Quote
Reply

Stonetooling.com   Tile-Assn.com   National Gypsum Permabase


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
How to Install Porcelain Tile over Plank Subfloor. Please help! thull Tile Forum/Advice Board 6 07-14-2017 12:14 PM
Leveling plank subfloor for kitchen tile installation Llama11amaduck Tile Forum/Advice Board 11 01-02-2017 01:31 PM
Porcelain Ditra Plank Subfloor. Questions before strarting valdo Tile Forum/Advice Board 5 05-14-2013 06:58 PM
Kitchen Tile Prep Over Plank Subfloor Rich P Tile Forum/Advice Board 10 10-28-2009 06:17 AM
Porcelain Tiles on Wood Plank Subfloor johnnyaico Tile Forum/Advice Board 5 08-26-2005 11:38 PM


All times are GMT -6. The time now is 06:20 PM.


Sponsors

Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2018 John Bridge & Associates, LLC