Shower P Trap freezing advice.

[DIYluke]

Good afternoon,
I am looking for some advice on a shower P trap installation.
I just converted a bathtub to a shower. The shower stall trap sits lower than the tub trap did. The bottom of it is only about an inch from the bottom of the joist (the top of the horizontal drain is only about 3/4" from the underside of the floor so moving it up isn't a option). It's over a unheated crawlspace and I'm concerned the water in the trap may freeze. I live in northern N.J. so the winters aren't awfull, but single digits do happen.
What would you pros recommend?
If there is a code approved trap that's low profile (I've just installed a standard PVC 2" trap) and reliable I'd try it.
Or if you recommend just adding more insulation below it I do have room (about 20" below) to stack Styrofoam boards. My concern there is if it's too far from the floor above it may have no warmth to hold in.

Thanks in advance.

 

[Reach4]

Or if you recommend just adding more insulation below it I do have room (about 20" below) to stack Styrofoam boards. My concern there is if it's too far from the floor above it may have no warmth to hold in.

You can put a remote-reading thermometer, and put the "outdoor" sensor near your trap, if you want to see how cold it gets down there.

For insulation, the insulation of choice would not be Styrofoam exactly. There are very good foam boards that you would cut up and use instead.
https://terrylove.com/forums/index....ment-wall-insulation-and-fire-blocking.59855/ names some insulation material, although the use they describe is not what you are doing.

 

[Sponsor]

 

[Terry]

I doubt that anything will freeze over an unheated crawlspace. The ground tends to stay pretty even, and then the upper portion of the home tends to trap that temperature. It's very rare to see a frozen pipe in a crawl space. You would have to have a pretty good exchange of air for that to happen.

 

[DIYluke]

Reach, Terry,
Thanks for the response. I'll listen to both of you. I have a remote probe for a thermometer I can tuck in there so I'll keep an eye on it this winter and if it looks like it's getting too cold I'll do something about it.
Otherwise I'll heed Terry's advice and wait and see.