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 06-05-2019, 08:31 AM   #1
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
Small bathroom floor replacement

Hi,

So great of you guys to help the DIYer’s out here.

Hoping some of you can take a look at my plan of attack. Thanks.

Replacing 8”x 8” ceramic tile with 1’ x 2’ tile on a 5’ x 8’ upstairs bathroom floor. (5’ x 11’ with tub) Removed old tile set in mud bed with mesh. Removed 3/8” plywood that was under mud bed.

Existing 3/4” by 5-1/4” boards running diagonally on top of 2” x 10” joists. Unknown wood type.
Deflection is 2143.

The floor seems flat except by the corner against tub where the top of the wood deteriorated a little from being wet. Will check entire floor again after screwing boards down tight.

Add blocking where hole is from laundry chute and fill in with pieces of 3/4”. Or can I just install the plywood over the hole?

Screw down existing boards with #9 x 2-1/2” deck screws.
Pre-drilling the boards and 2 screws per board where it crosses over joists.

Install 3/4” (23/32) douglas fir sanded exterior ACX plywood with 1-1/2” deck screws avoiding the joists. Perpendicular to joists and no ply ends line up.
Leaving 1/8” gap between plywood pieces and 1/4” from walls and tub.

Is screw pattern 6” on edge and 8” in the field? 2” from edge?
Should I fill any of the gaps with something?
Is backerboard the easiest for a 1st timer? Hardy Backer ok to use? Any recommendations?

Enough for now. I’m sure I’ll have more questions later.

Thanks,
Randy
Attached Images
 
__________________
Randy

Last edited by Randy M; 06-05-2019 at 08:38 AM. Reason: Title wrong
Randy M is offline   Reply With Quote
Sponsored Links
Old 06-05-2019, 10:23 AM   #2
Carbidetooth
Hmmmmm
 
Carbidetooth's Avatar
 
Join Date: Mar 2010
Location: Boise, ID
Posts: 1,317
Hi Randy, I can almost guarantee your deflection number isn't L2143.

I suspect you're figuring that by size of room. Unless there's another room same size directly below and those walls carry that weight to foundation...well, I've never seen such.


Span is unsupported length of joist. And on a second story, the end supports are defined by load paths to foundation, not partition walls.


Let's figure that out and proceed knowing we're good framing-wise and go from there.
__________________
Peter

Silicone Sealant Ranger
Carbidetooth is offline   Reply With Quote
Old 06-05-2019, 12:27 PM   #3
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
Definitely bearing walls on both sides of the 5' width(footings below both). Same size room below (1/2 bath and laundry room) I used 5-1/2' on the deflecto. Thanks for making me double check. Measure twice, cut once.
__________________
Randy
Randy M is offline   Reply With Quote
Old 06-05-2019, 12:49 PM   #4
Carbidetooth
Hmmmmm
 
Carbidetooth's Avatar
 
Join Date: Mar 2010
Location: Boise, ID
Posts: 1,317
That's unusual, maybe an addition?

Anyway, I'd cut diagonal the unsupported boards to center of adjacent joists and patch in new 1x6 and the rest as you've described.


Yes on screw spacing. Gaps in tile backer need mesh tape and mortar.


I'm a big fan of decoupling membranes like Ditra or Stratamat. Less so of tile backer, but it's cheap and will work. Hardie is thirsty, beware when setting tile, mortar on the loose side and don't dawdle after combing, lest it skin over. Check for coverage on first couple of tiles.
__________________
Peter

Silicone Sealant Ranger
Carbidetooth is offline   Reply With Quote
Old 06-05-2019, 03:37 PM   #5
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
Thanks Peter,

Does it matter if thinset gets into the spaces between the plywood?
Should I silicone them or ?

Thanks
Randy
__________________
Randy
Randy M is offline   Reply With Quote
Old 06-05-2019, 05:25 PM   #6
Carbidetooth
Hmmmmm
 
Carbidetooth's Avatar
 
Join Date: Mar 2010
Location: Boise, ID
Posts: 1,317
Nope, it doesn't matter. Seems counterintuitive, I know, to fill space you specifically left, but it's standard fare. I wouldn't fill it with silicone, whatever thinset mortar gets in there is OK....really.
__________________
Peter

Silicone Sealant Ranger
Carbidetooth is offline   Reply With Quote
Old 06-07-2019, 08:20 AM   #7
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
Do I need to pre-drill the the plywood?
Or will an 1-1/2" self drilling screw w/shank work.
It seems like all the screws are advertised as no pre-drilling needed.
__________________
Randy
Randy M is offline   Reply With Quote
Old 06-07-2019, 09:15 AM   #8
Carbidetooth
Hmmmmm
 
Carbidetooth's Avatar
 
Join Date: Mar 2010
Location: Boise, ID
Posts: 1,317
Randy, there are those that would say yes, but I rarely predrill. The concern is what's called screw jacking and it manifests if entire shank is threaded.

I use these for all kinds of things. The upper shank is designed to kinda hog out area that would be pre-drilled. I'd actually use 1 3/4" for a job like yours. Gets a full bite in boards and leaves some head scratchers below. Not enough to be concerned about hitting joists, though. Actually, I'd likely use these for screwing boards to joists as well unless tops were soft and I needed the extra length.
Attached Images
  
__________________
Peter

Silicone Sealant Ranger
Carbidetooth is offline   Reply With Quote
Old 06-07-2019, 09:58 AM   #9
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
Thanks again Peter,

So I'll use the 1-3/4" for both boards to joists and then plywood to boards.
No pre-drilling needed.
__________________
Randy
Randy M is offline   Reply With Quote
Old 06-07-2019, 11:46 AM   #10
ss3964spd
Registered User
 
ss3964spd's Avatar
 
Join Date: Jul 2005
Location: Fairfax, Va
Posts: 1,862
Send a message via Yahoo to ss3964spd
Randy,

Peter certainly has more experience than I do but from my DIY experience 1 3/4" screws through 3/4" ply may not get enough bite into the boards below. I tried that length - some would bite while others would spin. I'd go with a minimum of 2".

I was screwing down a 2nd layer of 3/4 ply on top of 3/4 ply, so maybe the 1 3/4" into your floor boards will work better.
__________________
Dan
---------------------------------------------------------------------------------
If I recall correctly my memory is excellent, but my ability to access it is intermittent.
ss3964spd is offline   Reply With Quote
Old 06-19-2019, 09:10 AM   #11
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
Not all diagonal subfloor boards flat

Thanks for everyone's help.

I’ve screwed all diagonal boards to joists & repaired hole.

I’m using a 3’ & 7’ straight edge to check for flatness.

In a few spots a portion of one diagonal takes a dip of 1/16 – 1/8” between two boards that are flat.

Is it ok to set 3/4” plywood now?
Maybe not screw into low spots or does it matter since the boards on both sides of low spots are flat?
A piece of felt or roofing shingle in low spots?
__________________
Randy
Randy M is offline   Reply With Quote
Old 06-19-2019, 09:22 AM   #12
Carbidetooth
Hmmmmm
 
Carbidetooth's Avatar
 
Join Date: Mar 2010
Location: Boise, ID
Posts: 1,317
I'd overlay without regard to minimal low spots. The plywood will sort of average things out. I almost hate saying that because it sounds so ambiguous, but I've never had it become a problem.

Just say no to felt or shims.
__________________
Peter

Silicone Sealant Ranger
Carbidetooth is offline   Reply With Quote
Old 06-19-2019, 09:26 AM   #13
cx
Da Home Builder
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 87,886
Quote:
Originally Posted by Randy
...a portion of one diagonal takes a dip of 1/16 – 1/8” between two boards that are flat.
'Fraid that doesn't compute for me.

You want to screw the 3/4" plywood at the same fastener schedule throughout. If you end up with an insufficiently flat floor, you'll need to deal with it at that level. I can envision a scenario where filling a minor depression with roofing felt or similar might be advisable prior to installing the plywood panels, but I'm not sure what you have there.

I'm one of the people Peter said would recommend pre-drilling that 3/4" plywood before installing. Maybe some folks can get by without doing so, but I have insufficient gravity to guarantee no screw-jacking with anything thicker than nominal half-inch material.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Old 06-19-2019, 10:00 AM   #14
Randy M
Registered User
 
Join Date: Jun 2019
Location: Santa Clarita, CA
Posts: 12
So i'll install plywood as is & then check for flatness and deal with a self leveling compound or something if needed.(Hopefully not)

I only weigh a 140 lbs so I'll drill pilots.
Are the pilot holes the same size as the shank on the screw so no threads bite into the plywood?
__________________
Randy
Randy M is offline   Reply With Quote
Old 06-19-2019, 10:17 AM   #15
cx
Da Home Builder
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 87,886
No bigger than the shank size, Randy. The threads will still bite into the plywood, but will strip out quickly. And if you use fasteners that have more than 3/4" of unthreaded shank below the head, you may get by without the pre-drilling. I'd still pre-drill 3/4" material, but that's entirely up to you.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx 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
axa small bath axa Tile Forum/Advice Board 21 02-03-2013 04:53 PM
Subfloor replacement patch - biggie or small? Topspin Professionals' Hangout 6 08-21-2010 07:11 AM
Bath tile removal and replacement Mike DIY'r Tile Forum/Advice Board 6 06-24-2009 02:50 PM
? on small Bath remodel aletamarie Tile Forum/Advice Board 32 11-15-2007 07:17 AM
no barrier in small bath Robert Hilborn Tile Forum/Advice Board 1 03-06-2007 06:24 AM


All times are GMT -6. The time now is 02:15 AM.


Sponsors

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