Utility room drain design

Hi all,
I need to build a drain for a 2nd floor 3'x6' utility closet. The closet contains a condensing hot water heater and hydronic radiant distribution plumbing.

I'd like to make the whole closet floor into a sloped waterproof pan with a drain in the middle. Is there a recommended design for this?

Since it's just for emergency use, I imagine an adequate method would be to use thinset on top of the plywood deck to slope the floor to the drain, then top with a waterproof coating. Or should I go with a full up shower base type arrangement with a membrane?

Any suggestions on the design and specific floor drain type to use?

Thanks,
Hazel

I would give some thought to the trap design. I do not know what your heating season is, but that trap will likely go some time without receiving any water. In order to avoid losing your trap seal, you will need a self priming trap. Though, I have seen a new device that uses a sort of curled up tube that allows water to pass, but then curls back up to seal the trap. I forget what it is called, but perhaps someone else will know. I am not sure about this product's code acceptance status, but it seems useful for certain situations. As far as the deck, If you are going to take the time to do a mud deck, you might as well install a proper shower pan. That way you can just run a hose bib in the room right onto the floor.

I have seen 2nd floor laundry closets with a 1 in deep galvanized sheet metal pan with a drain in the center. If it is just for emergency draining, the drain could be directed to a sump pump pit and wouldn't need a trap.