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-   -   Schluter help (https://www.johnbridge.com/vbulletin/showthread.php?t=88447)

oakland76 06-26-2010 11:13 AM

I am renovating my small bathroom which has a shower in it. The bathroom is about 12'x4.5' and I have removed a fiberglass shower stall to make way for tile. I am a little concerned about putting so much weight (of the tile) in such a small area. There is a finished room below it so getting good access to the floor joists will be problematic. We are putting a French pattern travertine tile on the bathroom floor, a staggered square travertine tile on the shower floor, 18x18 travertine on the shower walls and a 1x2 split face brick pattern on one wall to a height of about 4 ft. Should I worry about my new bathroom falling through the floor or is just novice jitters? Thanks in advance for your help.

bbcamp 06-28-2010 04:22 AM

Jason, your travertine floor tiles impose greater demands on your structure than simply it's weight. The deflection criteria for natural stone is twice as stiff as for ceramic tile. Chances of your floor meeting this criteria are slim, if stone floors were not specified during construction. To check to see if the joists are stiff enough, use the Deflecto tool (in dark blue tool bar above) and enter your joist information: size, spacing, and maximum unsupported span. The subfloor must also be stiffer than for a ceramic tile floor. The standard is 2 layers of plywood or OSB, with a minimum combined thickness of 1-1/4" and no layer less than 3/8" thick.

The ability of your house to carry the weight is not an issue. It won't fall down. However, it may bend enough to crack the travertine or the plaster ceiling below it. That's why we check the structure as the very first step in installing tile.

oakland76 06-28-2010 08:52 AM

Thank you so much Bob. Ill let you know how it goes.

oakland76 06-28-2010 09:13 AM

Does "Joist Length" refer to the length from the sill plate to the support where the joists overlap? What if they are supported from below by a load bearing wall or girder? My deflecto score is telling me to get wood flooring. Can I shore up the floor even if I dont have access to the entire length of the joist? The joys of home ownership :(

cx 06-28-2010 09:19 AM

Joist length is the unsupported span of the joist, Jason. Any structural support under the joist counts as reducing the span.

You can add to the rigidity of the joists if you can effectively sister a minimum of the center 2/3rds of each one in the area to be tiled.

Adding a support wall or beam can often give you more bang for your buck if you have the option to do that.

My opinion; worth price charged.

oakland76 06-28-2010 07:09 PM

The bathroom is over a finished bathroom but I crawled under the house and saw the unsupported distance is only 10 ft. I cant put a wall or beam under it but I can probably sister it. Thanks CX. There is a dip in the floor but I think it might be from a damaged sub floor but Ill find out for sure next weekend when I tear it up. I was thinking about using all plywood for the sub floor then a layer of Schluter Ditra in the dry areas and maybe a Schluter shower pan. Do I have to worry about the weight of the travertine on the Schluter pan? Any particular plywood type woks best with the Ditra?

I want to use the schluter membrane on the shower walls but again I am worried about the 18x18 travertine pulling the membrane away from the wall. Would I be better off with cement board?

I am installing 1x2 split face travertine brick pattern tile on the wall up to a height of about 4 ft. I am planning on cement board behind it, any objections? Again thanks for all the help you guys are giving me, Ill put up some pictures when it is done.

bbcamp 06-29-2010 04:38 AM

Adding a beam or sistering the joists under the first floor bathroom won't help the second floor bathroom. Or did I read something wrong in your last post?

You do not have to worry about the weight of the travertine on the Kerdi pan.

Use Exterior rated plywood, with no face grade less than C (A, B or C is fine, D is not). You can use Exposure 1 OSB, if you want. Don't forget that your subfloor will need 2 layers of plywood.

Kerdi will stick fine to drywall. A square foot of travertine weighs no more than a square foot of tile of the same thickness. The weight of the travertine will try to shear itself off the wall. However, even the worst thinset has many times more shear strength than you need. That said, you still want a good un-modified thinset mortar for this. The $5 a bag stuff at HD is not it. One last thing. Do not be tempted to pick at a corner of Kerdi to see if it sticks (except to check coverage while installing). You can do it, it will peal off, but that's not a good test. Like I said, tile will try to shear off the wall, not pick at a corner. Leave the Kerdi alone.

If the 1x2 split face is in a dry area (outside the shower and tub surround), you can set them on drywall, if you want. If they were inside the shower, I'd re-think my choice of tile. All those crevices will catch soap scum and be hard to clean. The tile will be hard to grout, too.

oakland76 06-30-2010 07:40 AM

Thanks Bob. Maybe I was a bit unclear in my previous post, I intend to sister the floor joist (if anywhere) of the bathroom I am working on not the one below it. The split face travertine is going in the dry area behind the toilet, and vanity. We plan to have it go to a height of 4 ft but if it turns into a pain in the a$$ with the wall mount faucet then I will reconsider my plan. Thanks again.

oakland76 07-04-2010 01:23 PM

I am pulling up the rotten plywood which is on top of a plank subfloor and found what looks like rosin paper between the layers. The work was done in 1979 or 1980 so should I worry about asbestos?

Brian in San Diego 07-04-2010 01:30 PM

I don't there is need to worry about the paper. It was installed as a "slipsheet" and I don't think it was ever made of asbestos.

oakland76 07-05-2010 10:20 AM

More subfloor problems
I am also converting a second bathroom into a laundry room. I removed the old tile and wonder board and found a layer of vinyl over a base of particle board. The particle board is laid on top of the plank sub floor so I am missing a structural layer of sub floor. I want to tear up the vinyl and particle board but after several successful advertising campaigns, I am worried about mesothelioma. I believe the vinyl is from before 1970. Any suggestions other than having a piece sent to a lab (I would like to do this today).

oakland76 10-21-2010 05:04 PM

Schluter help
I installed the Schluter shower system in my bathroom and just passed the water test with the inspector and now I'm ready to tile. I am using 18x18 travertine tile with the first course 18x18 and alternating 9x18 courses up to the cieling. It appears that Schluter reccomends using unmodified thinset for tile installation but my tile guy reccomended a thinset for large format tile that had latex in it. Any suggestion?

cx 10-21-2010 05:11 PM

I suggest you ask your tile guy if his warranty is better than the Schluter warranty. :)

This the same bathroom you're working on in your other two threads, Jason?

Shaughnn 10-21-2010 05:17 PM

hi Jason,
There is no need for a "large format tile" here as the thinset doesn't have to resist the weight of a larger tile, being that's it's mounted to a wall. Your installer can use a good quality non-modified thinset here and not worry.

oakland76 10-21-2010 05:32 PM

CX, I actually have two projects going at the same time, a laundry room and the guest bathroom. It sounded like a good idea at the time but now I think I should have done one at a time. I will use the same unmodified tile I used to install the Schluter. I have seen some online videos that show using a ledger board screwed into the wall but that seems like a terrible idea with the Schluter. I was planning on installing my floor tile when I get home then letting the thinset cure and installing the wall tile this weekend. Any objections?

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