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
Unread 02-12-2013, 04:13 PM   #1
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Curbless shower question + subfloor thickness

Hello - I'm new here. I'm in the process of doing a complete master bathroom renovation. I purchased the latest ebook and read through it, but still have some questions that I'm hoping you guys can help me with.

1. Curbless shower
I've settled on going with a kerdi linear drain shower tray (the one that comes in 55x55) and trimming to fit my shower + the keri line trench drain. The shower itself will be between 4-5 feet wide and 55" long. That means I need 2" of slope from the entrance of the shower to the front (where the drain will be).

My initial plan was to notch the joists down 2" in the shower area, then install subfloor and the shower pan. Is this the standard way to accomplish a curbless entry? Does anyone have advice about the best way to do it? I assume that I'll need to add additional cross supports to accommodate for the weakening of these joists.

The only other idea that I have is to install additional subfloor everywhere else to raise it up - but that would create an annoying step into the bathroom from the bedroom.

Information about the joists - 2x8, 16" on center, from the back of the house to the center (where the main support beam runs) is 13.5'.

My second question is along similar lines. I am going to go with porcelain tile (probably 20x20 for most of the floor). I'm going to use the 1/8" ditra as an uncoupler/water proofing membrane. I talked to a guy at Schluter today and he said it would be fine over 5/8 tongue and grove - but everything that I've read here recommends getting around 1 1/4". I currently have 5/8 OSB tongue/grove down but have removed big sections of it to move plumbing around.

Thank you so much for your help - I appreciate it!
Charlie
__________________
charlie
charlieaf92 is offline   Reply With Quote
Sponsored Links
Unread 02-12-2013, 07:36 PM   #2
John Bridge
Mudmeister
 
Join Date: Mar 2001
Location: Rosanky, Texas
Posts: 67,692
Send a message via AIM to John Bridge
Hi Charlie,

Check the size of those joists. 2x8 strung out 13 feet is not very good to begin with, and you're talking about cutting them down. Maybe they are 2x10?

Schluter says 5/8 is okay. There is no requirement for 1-1/4 in. for tile. There is a two layer requirement for stone tiles, but not for ceramic.
John Bridge is offline   Reply With Quote
Unread 02-12-2013, 08:58 PM   #3
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Thanks for the prompt reply John. I just double checked and they are indeed 2x8 (actual measurements are closer to 1.5"x7"). The run from the back of the house to the main support beam is between 13' 3" and 13' 6" and they are 16" apart.

I am going to be taking up almost all of the sub floor in the bathroom - which begins at the back wall and goes 9.5' towards the center. So, for that much of the joists I'm able to double/triple them up if necessary. In addition, the bathroom is directly above the kitchen which has a dropped ceiling so there is a lot of space below the floor. I could use 2x10s or bigger when I'm doubling things up and they can extend downwards without issue.

I've attached a picture of what the joists look like.

Thanks again for your help!
Charlie
Attached Images
 
__________________
charlie
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 08:17 AM   #4
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Good morning - I have two questions that I hope you can help me with.

1. Is there a way to measure joist deflection without specialized tools?

2. What joist deflection is appropriate for ceramic tiles when installed over 5/8" tongue and groove OSB and 1/8" Ditra?

Since my last post I've done the following
  • Spoke with an architect regarding the best way to approach the problem
  • Sistered 6' 2x8s starting at the side of the house with liquid nails and carriage bolts every 16" alternating from top to bottom. I notched the edge of these so they are sitting 'down' 2" below the original floor height.
  • Trimmed approximately 2" from 4 joists starting at the wall and coming out 43.5" into the room
  • Added additional bracing between all of the joists that were trimmed

So, now my floor is at the proper height for the curbless shower. The joists feel solid, but I do notice some slight visible deflection when someone steps directly onto one. It doesn't seem to be any different than the deflection I can see on an un-cut joist. I still have some cross supports to add in the area where the shower will be.

Before I glue/screw the subfloor down, I want to be sure I'm as sturdy as I need to be for the tiles. Any advice would be appreciated.

Thanks
Charlie
__________________
charlie
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 08:33 AM   #5
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Here are a few pictures to help illustrate.

Pic #1 is of the shower area, where the joists are trimmed down.

Pic #2 is to the area immediately to the right of pic #1. Pic #2 shows where the toilet and vanity will go. The foot traffic will be primarily between the front of the vanity and the shower.
Attached Images
  
__________________
charlie

Last edited by charlieaf92; 04-01-2013 at 08:38 AM.
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 08:55 AM   #6
Bodie Powers
Retired cabinet maker/remodeler
 
Join Date: Jun 2011
Location: Three Rivers, Oregon
Posts: 1,376
Charlie, do you have pics of the new joist setup?

To clarify:

You began with 7.25" joists and have cut 4 of them down by 2" so that they are now 5.25", and you then sistered 6 foot 2 x 8 (7.25") against the 5.25" cut down joists? Is this correct?

What are the individual spans of the original joists to which you added the sisters? I believe the rule of thumb is the sister should span the center 2/3 of the joist.

I'm not an engineer but I question whether the bracing is adding any strength to the joists.
__________________
Bodie
Bodie Powers is offline   Reply With Quote
Unread 04-01-2013, 08:59 AM   #7
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Hi Bodie - thank you for the reply.

You are correct. They are 2x8 and the actual measurement was about 7.25. The span is roughly 13'-13.5'.

If necessary, I can add another sister joist to the other side of the cut joists - it will be a lot of extra work but I'd rather do it now than after I'm done tiling.

Also - if there are any tests that I can perform to verify the deflection is good enough for tile would be great. My very unofficial test (standing on the joists and seeing how they 'feel') tells me that they are as solid as any of the others in the room.
__________________
charlie
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 09:01 AM   #8
Bodie Powers
Retired cabinet maker/remodeler
 
Join Date: Jun 2011
Location: Three Rivers, Oregon
Posts: 1,376
Charlie, what are the spans of the 4 joists to which you attached sisters? (I deleted my previous post because you beat me to it with the posted pics.)
__________________
Bodie
Bodie Powers is offline   Reply With Quote
Unread 04-01-2013, 09:07 AM   #9
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Thanks Bodie - the span is roughly 13-13.5'.
__________________
charlie
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 09:09 AM   #10
Bodie Powers
Retired cabinet maker/remodeler
 
Join Date: Jun 2011
Location: Three Rivers, Oregon
Posts: 1,376
Darn....I had to delete another post because you were already posting the answer before I asked the question...man, you are good
__________________
Bodie
Bodie Powers is offline   Reply With Quote
Unread 04-01-2013, 09:16 AM   #11
Bodie Powers
Retired cabinet maker/remodeler
 
Join Date: Jun 2011
Location: Three Rivers, Oregon
Posts: 1,376
What I was saying earlier is that the general rule around here is that in order for a sister to be effective it should cover the middle two-thirds of the span. If you added a 6 foot sister at the far end of a 13 foot span you might not be getting the desired additional strength. I'm not an engineer nor an expert; it might be worthwhile to discuss this with one of the more experienced moderators. And I'm not sure your idea of adding another 6 foot sister to the opposite face of the joist would be the solution because you would still have not met the two-thirds guidline. Is it feasible to add a 10 or 11 foot sister to the opposite sides?
__________________
Bodie
Bodie Powers is offline   Reply With Quote
Unread 04-01-2013, 09:21 AM   #12
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Thanks again Bodie. Anything is possible

It would definitely be difficult to get a bigger sister joist into that space though. There is plumbing I will need to notch around and bracing to remove/reinstall. But, if its necessary its necessary.
__________________
charlie
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 09:44 AM   #13
cx
Da Home Builder
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 88,443
Bodie, I put back your deleted posts to keep the following posts from seeming so disjointed. No need to delete anything relevant to the conversation, we got plenty room.

Charlie, I gotta agree with Bodie that you've essentially done nothing with your short sisters other than strengthen the square corner at the end of your rip of the original joists.

Your joist span was excessive for a ceramic tile installation to begin with, and ripping a couple inches from them made that situation substantially worse. You really need either some full length sisters (at least from the wall where the rip starts to within two feet of the other end) in there or some mid-span support near the end of those rips. This is especially true if you intend to tile the bathroom floor as well.

And from the look of what you're using for the sisters, I'd think you'd actually need to use a 2x8 sister, dropped to the height of the bottom of your rip, to actually achieve the deflection criterion you're looking for. And I see no mention of glue being used in your sistering operation. I miss something, perhaps?

Have you discussed this shower design with your code compliance officials, specifically the part where your shower entry will not be the required two inches above the shower drain?

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Unread 04-01-2013, 09:45 AM   #14
charlieaf92
Registered User
 
Join Date: Jan 2013
Posts: 27
Thanks for the reply CX.

When you say use a 2x8 dropped to the height of the rip - that is what I did. It is hard to tell from the picture. I ended up having to shave a small amount from the 2x8 sister to make things level, but it is just about complete.

Also - to clarify, I used a healthy amount of liquid nails between the sister joists in addition to the carriage bolts.

When you say mid-span support, what do you mean? Could I sister a 2x8 beginning after the notched area and running further down the run towards the center beam?

The shower will be to code, sorry for not being specific. I've dropped the entire shower floor 2" to accommodate the Kerdi LS shower tray. It is pre sloped. I'm using a kerdi-line drain with it.

Thank you again for your help, I appreciate it. I want to get 'right' so that I don't have to rip up the floor down the road.
__________________
charlie
charlieaf92 is offline   Reply With Quote
Unread 04-01-2013, 09:50 AM   #15
cx
Da Home Builder
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 88,443
By mid-span support I mean a support under your joists, a support beam or wall, somewhere other than the ends, preferably near the end of your rips.
Quote:
Originally Posted by Charlie
Could I sister a 2x8 beginning after the notched area and running further down the run towards the center beam?
Sure you could, but it won't buy you what you need in reduced deflection. You need to run that sister all the way to the wall past your ripped area.
Quote:
Originally Posted by Charlie
The shower will be to code, sorry for not being specific. I've dropped the entire shower floor 2" to accommodate the Kerdi LS shower tray. It is pre sloped. I'm using a kerdi-line drain with it.
Curious to see how you'll do that without raising the bathroom floor. Which, as an aside, I would certainly recommend given your very, very minimal subflooring.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   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
Question about subfloor thickness? matty 180 Tile Forum/Advice Board 7 02-21-2011 09:43 PM
another subfloor thickness question broke dad Tile Forum/Advice Board 18 12-08-2008 09:35 PM
Subfloor Thickness Question Gregg Tile Forum/Advice Board 3 09-02-2008 12:09 PM
Subfloor thickness question bladedge1 Tile Forum/Advice Board 26 09-02-2007 10:45 AM
Subfloor thickness question GaryB Tile Forum/Advice Board 10 02-20-2006 09:29 PM


All times are GMT -6. The time now is 01:08 PM.


Sponsors

Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2018 John Bridge & Associates, LLC