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Unread 03-16-2014, 04:31 PM   #1
DIYGrasshopper
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Deflection Calculator (and other) Help

This is my first post. I have to say, as a recent lurker, this forum is fantastic.

Recently, I got the DIY bug and bought a bunch of tools. I am working up my confidence and now it's time to tackle a couple projects...beginning with tiling my small bathroom.

My plan was to cut my teeth with our tiny 40 SF bathroom in hopes that I could be ready to tackle the 250 SF kitchen next.

Before I dive in, I ran the Deflect-O-Lator and got a big thumbs down. (I realized that it wasn't setup for my particular I-joists, so I thought I'd post to the forum).

I wanted to post here for help understanding deflection and if I need to scrap the plans to tile my kitchen (and possibly even the bathroom).

So here it is:

The kitchen is directly over the crawlspace so I got a good look at the joists.

-16" on center
-9 1/2" I-joists (TJI PRO 150 "Silent Floor" Joists)
-Span is around 15' 5"
-Subfloor appears to be 3/4" plywood (there is another 1/4" sheet with linoleum which will go away in both the kitchen and the bathroom)

Am I really "out of luck" for porcelain tile? (I'd like to do 20x20 or 18x36 in the kitchen, and purchased 12x24 tile for the bathroom).

Help!
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Unread 03-16-2014, 04:42 PM   #2
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Hi J,

The Deflecto does not handle engineered joists at all, only traditional dimensional lumber.

To find out about your I-joists deflection you can look it up from the manufacturer - http://www.woodbywy.com/products/trus-joist/tji-joists/

It would be unusual to not meet at least the L360 deflection requirement using engineered joists like yours.
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Unread 03-16-2014, 05:05 PM   #3
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Thank you Joe for the quick response. You have given me hope that I may be able to tile yet!

I actually had tried to find out more about the TJI Pro 150 joists that I have and had googled them (thanks for the link). It looks like the manufacturer has moved on and I couldn't find any information from the Weyerhaeuser site.

I emailed them to see if they can send me the details on the TJI pro 150 floor and hope they reply soon. (my house was built in 2001, so I'm guessing they don't carry the Pro 150 any more).

If anybody on the forum happens to know the details of this joist, that would be sweet. Otherwise, I'll post what I find out.
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Unread 03-16-2014, 05:34 PM   #4
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I found this information from another site:

TJI Pro 150 - 9.5" depth @ 16" o.c. with L/480 deflection criteria
Max Span with 40 Live Load & 10 Dead Load - 15'-7"

You only need L360 for ceramic/porcelain so you should be ok with what you've got.

Here is a link to some info from Miami building. It has your joist information on page two. http://approvalzoom.com/download.php?type=1&id=22520
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Unread 03-16-2014, 08:49 PM   #5
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Joe,

Way above and beyond! Thanks so much for tracking that info down.

Looks like I'll be tiling soon after all.



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Unread 03-18-2014, 07:33 PM   #6
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Now I am ready to begin...

OK,

So now that I know my floor deflection is within the specs of laying tile, I'm ready to begin.

I've watched tons of youtube videos and the big box store videos, but frankly I value the advice at this forum more.

So I am planning to add 3/4" hardwood throughout the rest of my house at a later date, so my bathroom needs to be at the future height for a good transition. I was thinking about going with Ditra XL, but I was a little dismayed that it doesn't seem to come in small rolls (and I have a 40 sf room).

The current floor has linoleum, so it has a subfloor and I'm guessing a 3/8" plywood on top of that.

My original plan was to tear out the linoleum and the plywood and go with the Ditra XL and thin set on the subfloor.

Since the 3/8" ply looks like it is in decent shape (2001 construction) could I just use the regular Ditra on top of the plywood and get the transition right?

Any issues going right over the plywood on top of the subfloor? (It looks like the linoleum is just glued down from my peeling up a small section)

Also for what it's worth, I purchased porcelain tile which will go on top of the underlayment I choose. I assume there is a thin set that will bond to porcelain over Ditra since it is a common install.

Thanks in advance.
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Last edited by DIYGrasshopper; 03-19-2014 at 10:01 AM. Reason: clarification
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Unread 03-19-2014, 10:48 AM   #7
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I'm ready to buy materials for my first tile project. Please help-

Bump:

OK,

So now that I know my floor deflection is within the specs of laying tile, I'm ready to begin.

I've watched tons of youtube videos and the big box store videos, but frankly I value the advice at this forum more.

So I am planning to add 3/4" hardwood throughout the rest of my house at a later date, so my bathroom needs to be at the future height for a good transition. I was thinking about going with Ditra XL, but I was a little dismayed that it doesn't seem to come in small rolls (and I have a 40 sf room).

The current floor has linoleum, so it has a subfloor and I'm guessing a 3/8" plywood on top of that.

My original plan was to tear out the linoleum and the plywood and go with the Ditra XL and thin set on the subfloor.

Since the 3/8" ply looks like it is in decent shape (2001 construction) could I just use the regular Ditra on top of the plywood and get the transition right?

Any issues going right over the plywood on top of the subfloor? (It looks like the linoleum is just glued down from my peeling up a small section)

Also for what it's worth, I purchased porcelain tile which will go on top of the underlayment I choose. I assume there is a thin set that will bond to porcelain over Ditra since it is a common install. (and I need to get the thin set right under the Ditra as well..i assume modified for under the ditra and unmodified for between Ditra and porcelain tile…or is that backwards)?

Thanks in advance.
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Unread 03-19-2014, 02:06 PM   #8
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I'd forget using that 3/8 underlayment. The vinyl glue( which won't come off without a fight) will interfere with bonding of Ditra and it's probably not adequately fastened to subfloor anyway. Vinyl isn't very demanding of substrate, tile very much is.

Were it me, I'd remove the 3/8 underlayment, replace with well fastened 1/2" ply, bond Ditra to that and then you're ready to tile.
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Unread 03-19-2014, 05:49 PM   #9
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Thanks Carbidetooth for the tip!
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Unread 03-19-2014, 06:00 PM   #10
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My plan and steps for installing new tile (first time)

OK, I am now "planning" my attack. I've tried to compile a list for step-by-step how I am going to do this. Since this is my first time, I want to get the steps and order of best practices down. I also figure this list (once it is reviewed and revised by y'all gurus out there) could be a good resource for other first timers.

Background: Laying tile in +/- 40SF bathroom that currently has linoleum over a 3/8” ply, on top of what appears to be a ¾” plywood subfloor. This is on top of engineered trusses that are 16” on center at spans up to 15” 5”. Specs of my trusses show a deflection of L/480 spanned at 15’ 5”, so I should be OK to tile. I plan to add ¾” hardwood throughout the main floor, so I want to tile at the same height for a smooth transition.

OK, see my proposed steps below. Please help revise/correct my plan based on your experience.

1. (Remove toilet and vanity first) Remove linoleum and 3/8” plywood

2. Screw subfloor to trusses every 8” or so to prevent future squeaks

3. Add ½” plywood with plenty of wood screws into subfloor, say every 10” or so? (for height and to save money on the Ditra XL. If there is a better way to get to match future 3/4" hardwood height I'm all ears)

4. Dry-fit the Ditra underlayment and make cuts with utility knife where needed

5. Make sure substrate is level, apply self leveling to any low spots if needed (do I level the subfloor or the ½” ply)

6. Mix and apply modified thin-set using 3/16” x ¼”V-notched trowel (if you have recommendations as to the best thin-set to use I’m all ears).

7. Lay out Ditra and press into thinset/substrate with a wood float butting sections next to each other (also, how long should I wait before working on top of the Ditra. I was under the impression I could get started right away. Also, do I do anything special with the seams of where the Ditra butts together other than making sure seams don't match up with substrate seams)

8. Dry fit the tiles and spacers and snap a grid for the center lines that allow for the most balanced cuts on either wall (I think I chose 1/16” spacers…I don’t remember…is there a “standard” spacing I should consider for 12x24” tile)

9. Apply unmodified thin-set to top of Ditra using the flat side of the trowel to smash thin-set into squares

10. Comb additional unmodified thin-set in one direction at 45 degree angle using ½” x ½” square notched trowel (I plan to lay 12x24” tile)

11. Lay tile and press evenly, adding spacers as I go (should I back butter 12x24” tiles?) Working in small sections

12. Make sure tiles are level using my 4’ level and tap tiles with rubber mallet to ensure they are level with one another

13. Leave ¼” gap along all walls and around pipes for expansion, and don’t grout in expansion space

14. Let tile set for 24 hours before applying grout

15. Remove spacers first, Press grout into joints with rubber float, then pull excess grout at diagonal angle across joint with float

16. Wait +/- 20 minutes and wipe grout lines in circular motion with sponge and clean water

17. Stay off floor for around 72 hours

18. Remove remaining grout haze with grout haze remover (brand recommendations appreciated here)

19. Apply a bead of silicone sealant to expansion gaps

20. Wait 3 weeks and then apply grout sealer (recommendations here as well. Is it better to add the sealer into the grout mixture when grouting the tile?)

Thanks to you all in advance! Writing that all out made me realize there are a lot of steps to tiling. My hats off to y'all experts out there on this forum. Thats a lot of work! I really want to learn some DIY skills for the satisfaction more than the savings. It has to feel good doing a job well done and admiring your work.
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Unread 03-19-2014, 09:41 PM   #11
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2. Shouldn't be necessary with an engineered subfloor, but it won't hurt.

3. That does not constitute "plenty." At a minimum you should fasten at 6" centers on panel edges and 8" in the field. Do not fasten into the joists.

5. Your tiles don't give a rat's patooti about your floor being level, they only want flat. And tiles the size you are planning want very, very, very flat. You must not do any flattening or leveling between plywood layers and must do it before the Ditra.

7. Please, please, please go to the Schluter website an download the Ditra Installation Handbook. Read until you are satisfied you have missed nothing pertaining to your installation.

11. If you mark out an adequate grid for your layout you should not need spacers except for the occasional tile that wants to follow you around. You'll generally get a better layout if you are careful to match your tile edges to your layout lines.

15, 16. We don't know what grout you intend to use. Read and follow that manufacturer's installation instructions.

19. What "gaps" are we talking about there?

My opinion; worth price charged.
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Unread 03-20-2014, 10:34 AM   #12
DIYGrasshopper
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Thanks CX for taking the time to review and reply to my post.

My responses are below


2. This is great news

3. Good to know, I will plan to beef up my view of "plenty". I am now debating if is should go to the trouble of adding 1/2" ply, or if I should try and find a smaller roll of the Ditra XL, or 1/2" hardibacker and save a step. Thoughts?

5. Noted. I'll plan to flatten prior to underlayment only.

7. I did try and read their installation instructions, FWIW I wrote my steps down while watching their installation video. I feel like I have my bases covered, but figured I'd post my steps for the experts here to tell me if I am missing anything obvious.

11. Thanks for the tip. I may still use spacers as this is a first try. Advice on the best spacing between 12x24 tiles?

15, 16. I haven't chosen a grout yet. I'm open to suggestions as to which grout is the best to use. I plan to buy what I can from Lowes or a tile specialty shop.

19. I was referring to the gap I create in step 13

I value your opinions.

Hope that clarifies your questions.
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Unread 03-21-2014, 06:48 PM   #13
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Help me pick a tile layout

I decided to layout my tiles to scale and see how the varying layouts would look in their future space.

I have read that it is best to balance cuts from one wall to the next, so my Option D shows balanced on all 4 walls. Since I have a vanity and toilet pretty much taking one side, I cheated the tiles left to have full tiles on the doorway entry side.

Please look at the 4 options attached and let me know what you'd think would work best in the space (and which cuts to avoid).

Shown with 3/16" grout lines:

Name:  Upstairs bathroom Tile Layout-03.jpg
Views: 300
Size:  15.6 KB

Name:  Upstairs bathroom Tile Layout-04.jpg
Views: 291
Size:  17.6 KB

Name:  Upstairs bathroom Tile Layout-05.jpg
Views: 282
Size:  15.9 KB

Name:  Upstairs bathroom Tile Layout-06.jpg
Views: 290
Size:  15.9 KB

Thanks in advance. Also, if anybody has feedback to my proposed steps a few posts back I am all ears.
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Unread 03-22-2014, 08:32 AM   #14
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Bump
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Unread 03-22-2014, 10:57 AM   #15
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Option A and D both look good to me.
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