marble window sill

[Cooler]

I am remodeling the guest bathroom.  There is a small window above the bathtub at the far end from the shower head. 

I am planning on replacing the painted wood sill with a sill made from 4" wide  x 3/4" thick marble.  I will install the sill and extend the width to make a small shelf for shampoo, etc.

Question:  What should I use to adhere the marble to the wall?

I will tile after installing the sill so the joint will be hidden.  One end of the shelf will be in a corner giving support to the short end.

I was thinking thinset or epoxy but I am open to other suggestions.

[crokett™]

I would screw cement backer board to the framing around the window and then thinset the marble to that. Depending on how far the marble extends out from the wall you may need corbels or brackets attached to the wall to support it.

[Cooler]

Part of the marble will tuck under the window.

I was planning on a cement backer board.  There would have to be a relief cut in the backer board for the sill to tuck under the window.  The current sill is nailed in place.   Obviously I would not nail in the  marble sill.

I could use thin set to attache to the underside of the window frame as well as to attach the shelf section to the wall.

[jteneyck]

We all call them sills, but it's not.  The sill is outside.  The inside piece is called the stool.  

John

[hbmcc]

Won't marble at a window sweat more than other materials?

[Cooler]

Won't marble at a window sweat more than other materials?

I don't know.  I had not given it any thought.  I had seen a home remodel show where they replaced all the sills (I mean "stools"
) for all the windows in the house.  They did not mention any  issues with sweating. 

Marble will certainly conduct more heat/cold than wood.  A steamy shower will probably see quite a bid of condensation, but probably no more than would appear on the glass of the window itself.

[Robert Adams]

I don't know.  I had not given it any thought.  I had seen a home remodel show where they replaced all the sills (I mean "stools"
) for all the windows in the house.  They did not mention any  issues with sweating. 

Marble will certainly conduct more heat/cold than wood.  A steamy shower will probably see quite a bid of condensation, but probably no more than would appear on the glass of the window itself.

      Most of my relatives live in Detroit and most every house I have been in there built from say the 70s on all had marble window sill ( no one calls them stools anymore). 

          As for sweating I dunnow but it doesn't matter in a bathroom as everything is going to be masonry and if something sweats it all will and it all needs to be built water tight anyway as it's a bathroom. 

         Sealing around the sill etc should be done the same way you are doing your tile base. If you are using cement board and redgard as your water proofer use it around the window. But using Kerdi would be easier though. Then just set your sill like a big piece of tile with a slope to the inside. 
 
              If that area isn't a wet area just use construction adhesive to stick it down.

[jteneyck]

      Most of my relatives live in Detroit and most every house I have been in there built from say the 70s on all had marble window sill ( no one calls them stools anymore). 

          As for sweating I dunnow but it doesn't matter in a bathroom as everything is going to be masonry and if something sweats it all will and it all needs to be built water tight anyway as it's a bathroom. 

         Sealing around the sill etc should be done the same way you are doing your tile base. If you are using cement board and redgard as your water proofer use it around the window. But using Kerdi would be easier though. Then just set your sill like a big piece of tile with a slope to the inside. 
 
              If that area isn't a wet area just use construction adhesive to stick it down.

People say and even write "Your welcome." these days, too.  Just because we all know what it means doesn't make it correct.   

John

[Robert Adams]

People say and even write "Your welcome." these days, too.  Just because we all know what it means doesn't make it correct.   

John

           It's like calling all skid steers bobcats or the one that annoys me is every time there is something on the news about an airport they refer to the tarmac.... There is no such beast there is the runway, taxiways the ramp etc there is nothing called a tarmac.  

 
             But I do agree with you and I nitpick about allot of other stuff that doesn't get called by it's proper term myself. It's a proper descriptive term for something not something or a word that can change as the language changes.

[Woodworm!]

you could use corian, or PVC board.