Proper Sink & Lav Drains?

[CCCBuilder]

Can someone specify when to use 1.5" or 1.25" traps? I read kitchen sink is 1.5" and any bathroom sink/lav is 1.25"? Is it requires that the traps have a slip/nut connection when they tie into the tee in the wall, or is the slip/nut connection only required for pulling the trap weir part out itself and that the trap can be glued into the tee in the wall? I see they make adapter glue in pieces to accept a threaded slip nut but they are very pricey for the piece?

 

[Terry]

Most new homes are plumbed with 1.5" to the kitchen sinks and lavs (bathroom sinks). We use a 1.5" trap that can be reduced on the vertical with a 1.5" x 1.25" slip joint washer.

 

[Sponsor]

 

[Mliu]

Is it requires that the traps have a slip/nut connection when they tie into the tee in the wall, or is the slip/nut connection only required for pulling the trap weir part out itself and that the trap can be glued into the tee in the wall?

Why do you feel the need to "glue" (solvent weld) the trap tailpiece into the sani-tee? If plumbed correctly, the slip joint will never leak and it gives you the ability to remove the tailpiece in the future if necessary.

If your drain gets clogged, a plumber may need to remove the tailpiece to snake the drain. What if your trap accidentally gets damaged and you have to replace it? If the tailpiece is glued into the sani-tee, then you may have to cut through the back of the cabinet, through the wall, cut out the glued-up sani-tee, and install a new one.