Kitchen Sink Under Window Question

[Jb9]

Sorry for the dumb question but I don't understand something. I constantly read that plumbing pipes should not be placed in exterior walls but rather located inside the conditioned space. Why are there so many kitchen sinks under exterior windows? Are the supply lines kept inside the wall and hidden in the cabinet? Can the DWV be kept out of the exterior wall too? Is the Ptrap really the only place water could freeze and that should be under the cabinet? I'm doing a design and this has always perplexed me.

 

[hj]

The water pipes can come up through the floor of the cabinet and there is no standing water in the drain lines to freeze. The sinks are put there so the "mother' can see the kids playing in the yard.

 

[Sponsor]

 

[Tuttles Revenge]

We install water lines on the most inside part of the wall and insulate between the exterior and the piping. Less risk if its a 2x6 wall, but pretty common even in 2x4 construction. But I'm in a fairly temperate climate in seattle.

 

[Jb9]

This is helpful. I appreciate these recommendations. I was also thinking the pex would come up into the cabinet box (thanks HJ) and the trap would be down there as well with the arm going into the 2x6 wall and immediately dropping below the floor into the crawler and joining the main. Vent PVC would be the primary DWV in the wall until it returned to the main vent. Climate here is cold so I will make sure I am on the interior/conditioned side of the insulation. I might try drawing what I am describing.

 

[Helper Dave]

NE WI here. We put exterior water lines though the floor. Drain and vent can be in the wall. No traps in the wall, though.

Just be cautious/aware that when drilling through window framing (king and jack studs) for your vent and drain, some inspectors will require you to support it with stud shoes.