I have laid 12x12 marble tile in my foyer. I laid it on Saturday morning and now it is Monday morning and its still not set. It is on top of subfloor with a layer of this felt/plastic composite underlayment. I'm wondering if it won't dry because its by the front door and its cooler there or I did something wrong.

What type of adhesive did you use?

The adhesive sounds to be the problem... did you by chance us pre mixed adhesive, if so that is what is wrong.

You'll need to pull the tile up and use thinset mortar, pre mixed is only used for small tile 4,6,8 nothing bigger. Using 12" doesn't allow enough air to dry the premixed adhesive out.

As for the plastic/felt, that is overkill but it should be underneath all of what you've put down, then the concrete board then tile

I used a adhesive called omni pro maximum strength.

Im not familiar with that particular brand however Glavine is right if it was premixed and not a thinset it will take forever to dry and will likely cause future adhesion problems .

Thank you to all for the advise! I pulled up the marble tile and cleaned the old adhesive up. (not fun at all) after it was dry. I laid new marble tile down using a marble and granite thin set. 10 hours later with fans on it, it was rock hard and ready to go. Thank you all again!

That's why were here. Your welcome

Glad it worked out