Plumbing geometry

[BluegrassRules]

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.

[master plumber mark]

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.

.

[BluegrassRules]

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?

[hj]

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.