Plumbing geometry

Hi

New to the forum due to replacing cast-iron DWV with PVC. But I'm confused about the geometry involved in plumbing because you're dealing with measurements along 3 axes. Does it really matter how critical your measurements are with regards to slope? Is there not enough variance along a run of 15-20 feet to correct your slope with bracing and supports? I'm rather "anal" when it comes to getting measurements exact but wonder if I'm overthinking this. I would appreciate any thoughts.

1/4 inch per foot

a 1/4 inch per foot is nice , if you can get it that way...


but basically it all runs down hill , even if thier is almost

no slope at all. Give it whatever fall you can and it will probably

work just fine.

.

Thanks Mark. I understand that the slope needs to be 1/4 per foot, but I'm curious about how the exactness of horizontal distances affects this. For instance, if I measure for my next run of straight horizontal from one 90* to where the center of the next 90* should fall at 45", what if cut that horizontal at 44.5", or 44". Is it really going to make all that much difference if I can adjust the slope with supports?

slope

As long as both ends are not "fixed"' so that you cannot adjust the pipe at one spot without affecting the slope further down the line, then there is no problem.