Porcelain Tile and Deflecto Results

[John Bridge]

Hi all,

Thomas emailed me that he was having problems posting this.

Hi,
I'm new to the forum and wanted to post the following question thread on
the "Tile Forum/Advice" board, but I can't added my attached JPG or even
link to it from my website. Can you tell me how to rectify this situation
and successfully post my question with the attached diagram??

begin post -------------------------

Hi!! I preparing to do my first floor tile project and was hoping to run a
few questions by the many experts following this forum. Project is
putting 16”x16” porcelain tile in our L-shaped foyer.

Knowns:
1)Subfloor is ¾” plywood.
2)Floor joists are 2”x8” over a 12 foot span.
( I do realize this is not good enough for porcelain tile, but do to our
special foundation arrangement this is the source of my primary question
below.)

Plans:
1) Please see diagram below… Reinforce the 12 foot spans with sistered
2”x8” BUT because our basement is finished I can only reinforce the hallway
part (A2) of the foyer (the longest unsupported span)
2) Glue/screw down another 1/’2 plywood over current sub-floor AND then
another ½” of cement backerboard over that.

The Blue Numbered elements in the diagram are floor-supporting
foundation and beams elements. The Red Lettered elements are the 12 foot
spans and the Green Lettered elements represent the 12 foot spans that are
in fact broken into smaller spans because of the foundation elements. Note
that the staircase to the basement in the front of the house and the fact
that the house overhangs the foundation in the back of the house may be my
saving grace in this project. The 12 foot spans are actually shorter due to
these foundation elements.

Picture Should be here. [img} won't work or your attachment routine. Kept
getting an error.




1) Will I be OK installing porcelain tile in this foyer based on my
assumption that most of the joists spans are actually less than 12 foot (10
foot and 8 ½ foot, respectively) OR is my assumption that the our
foundation/stairway arrangement makes this “do-able” flawed??
2) If you feel this arrangement WON’T work for porcelain tile will it be OK
for ceramic tile??

All useful input is welcome and really appreciated. Thank you for reading
this far. Please excuse my obsessive detail. I just don’t want to glue
everything down and have grout cracking after a few weeks. Thanks.

[Trask]

Hey Thomas and Welcome,

Anyone with"beer " in their name will get speedy responses here
If I understand your long spans will be sistered (Becoming 3"x8"effectively)and they are app. 10'. The balance of the floor is supported by the 2x8 spanning just over 8'.
That seems to calc. pretty well (l/620) which is good enough for ceramic or porcelain. I think your O.k on the single layer ply if you go with ditra..however more is always better. Wonderboard or Hardi are gonna wanna see double layer ply.

Don't start gluing yet...let some of the "more expert" guys look over this

[SVT01]

Trask...thanks for the quick response. To confirm... the only 2x8x12' joists I'll be able to sister are the 2 or 3 under the foyer hallway noted by "A2" in the diagram. I'm working on the assumption that the back foundation (1) and stairway box (3) effectively give me shorter than 12' spans (10' (C) and 8 1/2' (B)) respectively. So as long as my assumption about the stairway box (which runs from basement to second floor) beginning strong enough to support the bulk of the foyer floor without flexing is correct I think I'll be alright.

Side note...our Beers family name comes from the shortening of the name "Przybyszewski"....which no one could pronounce when my grandfather was in the Navy. So they called him "Two Beers and a Whiskey" because it sounded somewhat like the proper pronounciation of his Polish name. After his Navy stint he shortened it to "Beers". I kid you not. Names closer to the drink than most people realize. LOL.

Thanks again. Have a nice Holiday weekend.

Other expert responses welcome.

[SVT01]

bump to top....Would anyone else care to lend an expert opinion regarding the "do-ability" of my foyer tiling project? Thanks.

[GraniteGirl]

I couldn't help you with your questions, but your last name is one of my favorites and the drawing you sent along is just great.



And now you're back on top again

[SVT01]

Jeez....tanx. I tend to get excessive with both drink and draw...just kidding. It's good to be on top again. Of course, the original question remains. Any additional expert comments would be appreciated.

[Trask]

Thomas, maybye that means your fine..I'd give it another day or two for reply's

[MudMaker]

Very nice drawing Thomas - your back on top again....

[SVT01]

I'm planning on putting porcelain (16"x16") tile in our foyer and ran my spans on the Deflecto analysis. Joists are 2x8' with spans that vary and include 12', 10' and 8'. (Center stairwell effectively shortens some spans.) My plan is to sister 2x8's on the 12' spans and 2x6's on the 10' spans, but I'm not sure how to run this on Deflecto.

I know I'm short without sistering, but will I be O.K. as planned? How do I calculate the effect of sistering?

Can I get away with 2x6 sisters on the 12' spans?

Finally, the Deflecto only shows Ceramic and Stone...how would I a run a Porcelain tile analysis...is there are conversion factor?

Thanks.

[muskymike]

Hi there, gotta first name we can use? Porcelain is the same on the deflecto as ceramic. You should be fine sistering with the 2x6, however 2x8's would be better.

[cx]

Welcome, Thomas.

I've merged your previous thread in here to save a whole gaggle of redundant questions and answers trying to 'spain what's so clearly shown in your drawing - which is 'zackly what my first request was gonna be.

Don't know why your thread got lost before. I claim innocence, beinashow I was off workin' inna mountains at the time. At any rate, here we are and here we'll stay. Keep all the questions on this thread, please. And go to the UserCP button near the top of the page, find the Edit Signature button and enter your first name so it will appear at the bottom of each post.

To bidness: Nowhere do I see mention of the spacing of these joists, nor the probable type of wood. Fill in those blanks for us, please.

Sistering the longest spans of the 2x8s may take care of your problems. Or not. The matter of the cantilever at the back of the structure is gonna be somewhat problematic. While it might seem that it shortens the span of those joists, it's actually a good deal more problematic than that. We'll need to know just what is above that area (and below if it's not just exterior empty space) and how it's constructed and used.

Even at that, I can't give you a scientific evaluation, but Injineer Bob may be able to give you a good guess.

For clarification, all porcelain tile is ceramic tile, but not vice-versa.

My opinion; worth price charged.

[SVT01]

Thanks cx and muskymike. Name's Tom. Sorry for the double post. Since I didn't get a lot of response the first time I thought maybe I over-spoke my case.

The cantilever in the back of the house supports 2 floors. Note in the diagram that on the first floor the foyer floor ends at a small powder room (with toilet near the outside wall). I measured the span again in the basement...it's about 9'6" from the center of the central beam to the center of the foundation wall. Figure another 3" or so of foundation wall and I guess you've got about 2 to 3 feet out the back. There is already ceramic tile in the powder room which I may change to the foyer tile. If I had to I can probably use 2x8"s to sister the 3 joists under the foyer in the back of the house. Due to the plumbing and ductwork in the back I'll have to slide them in from the other side. I suspect I'll have to chisel the new joist ends to get them up next to the existing joists.

Regarding spacing and wood quality...like DOH!!...I never realized I didn't put the spacing in my diagram....16" centers. Wood-wise I may be embarassed to report the only label I can find on the wood says..."No.2 S-GRN North Species". Green wood construction?...figures. Wood looks sturdy enough (he said fearing the worst possible answer) and mostly knot free (if that means anything at all... LOL).

Thanks again for your interest and help.

[bbcamp]

If your powder room tiles have not cracked, and you promise to sister the joists with 2x6s in area A2, and you verify the stairway framing does indeed support the floor joists, I'll give you the green light to proceed with tiling. I don't think you need any more plywood, unless yours is rotted or some such. 1/4" backerboard is plenty thick, too.

How's that for technical advice?

[cx]

What part of the country, Tom?

[SVT01]

thanks bbcamp. No cracks in powder room floor. Floor joists are saddle-bracketed (if that's what you call them?) to the stairwell box which runs from the basement up to the second floor. In the front of the house the joists run from these brackets to the outside foundation. I measured about an 8' span. On closer inspection there is a double joist running right across to the central beam directly under the door way to the first floor. It's part of this box. This should help for sure. Don't I need 1 1/4" total sub-floor including underlayment for the porcelain tile? Right now all I have is the 3/4" plywood which is in good shape.

sorry cx, I updated my signature and confirmed it was enabled, but it didn't show up. I'm in central New Jersey.