Any suggestions....

[Bill Vincent]

One thing I'm noticing on alot of threads concerning the tiling of ceilings. Everyone's so nervous about setting large format tiles. I'll agree that it would make a difference to go to mosaics-- not because of the size, but because of the THICKNESS. So long as the tile's the same thickness, there will be no difference in weight between a 4x4 tumbled stone wannabe and a 24x24 rectified porcelain tile. They'll both be the same weight. So long as you make sure you have good coverage, it'll stay up just as well as that 4x4, because although you'll be holding up more weight, you'll also increase the bonding surface proportionately, and therefore, there's virtually no difference. Use a non-sag thinset and notch trowel both the ceiling and the back of the tile, hang it and walk away.... or DON'T. Heck I don't even worry about havin a hardhat with me any more!!

Also, to add onto Jonathan's post-- he gave you the weight for the CBU, but not the tile! Figure about 4-5 pounds for the tile, and about half that for mosaics.

[MudGuy]

Naaaah Bill, I meant both backer board and tile to be no more than 6 lbs/sf...
However, upon closer reading, it may actually just refer to tile weight.


"The weight of the tile shall not exceed 5 psf for 1/2" backer board with framing spacing 24" o.c.; 6 psf for 1/2" backer board with framing spacing 16" o.c."

[cajtar]

Before you recommend any backer, thinset, tile etc please get an engineer - maybe Injineer Bob can confirm???

Floor live and dead loads assume the loading is coming from the top of the joist only. Dead loads include subfloor and any top flooring. Deflection limits assume some type of floor application (usually not stone unless specified prior to construction). Deflection limits for the top surface (L/360, L/480 etc) are more than sufficient for the typical ceiling drywall and popcorn application which is applied to the bottom of the joists (i.e. the ceiling will not crack or fail b/c of joist deflection).

What is NOT assumed when designing floor joists is a large dead load on the bottom of the joists (i.e. your ceiling tile application). If the top of the joist is designed to handle 20psf dead load, and your going to add another (assumed) 20psf to the bottom you have just overloaded the floor joists.

I'd be worried about liability if proceeding w/o advising an injineer...

[Bill Vincent]

What happens with granite, that usually weighs in at about 7 pounds per foot, give or take?

[gueuzeman]

What Todd/cajtar said had flickered thru my mind the other day. These things are made to support a weight pushing down from above, not the other way.


And what Bill said, the weight has to do with the density of the material, what size they're chopped up into doesn't matter.Years ago we hung some 18's or 20's on a shower ceiling, it was a bit of worry, but really not if you do it right.

Insted of tile do something light like metal sheeting. Here's something I did a year ago, 3 foot by 8 foot "tiles".



gueuze