Hi Everyone - it's been a while since I've posted and we've since moved into a new house. I don't post often because generally I can find what I need but this one has me scratching my head. Both full baths have 3/4" lines branching off a 3/4" trunk from the basement. Every other fixture in the house has straight 1/2" running to it branching off the same 3/4" trunk. The fixtures in the bathrooms are reduced from 3/4" to 1/2". I want to install a PEX manifold in the basement as it's unfinished and have every opportunity to make things the way I want but I can't find manifolds that do 3/4" outlets. I've also never had water pressure issues with 1/2" lines running to the bathrooms since I'm pretty sure the flow is more than enough to support a shower, sink and toilet as long as it comes off a 3/4" trunk. The question is this: would there be any issues running a 1/2" line from a manifold to a 3/4" line that runs up through the walls and gets reduced back down to 1/2" in the bathrooms. I wish it was just a straight shot up the walls because I could snake a 1/2" line up the 3/4" pipes but there's lots of turns going through walls and floors. I don't believe I'd see a pressure drop since I wouldn't be pulling more than a normal 1/2" line can provide, but I wasn't sure if up-sizing the diameter would reduce the overall pressure...it's been 10's of years since my last physics class... If it helps, we're on a well system here that goes from 1" from the pressurized bladder, down to 3/4" to the filters and so on. The bladder is set to the default of like 25-40psi (kicks on when tank hits 25, off when it hits 40). I have a good bit of room to increase the pressure if necessary.

OK I am sure I am using the wrong terms for some items but here's my question. I have read that when tying vents together the horizontal run in the vent should also carry the 1/4" per foot slope but is it supposed to slope back to where it originates and it will "drain" into it's own drain or slope it to the main vent stack and it will then drain down the 4" crapper drain? this is how its envisioned in my head. the wall has the toilet in the middle sink to left tub to right all on same wall. toilet flange is instant 45 and it goes back to a 4" stack which will also have some sanitary tees in it that bring in the drains from tub and sink (pretty sure Ive seen one with 4" top and bottom and 2" left and right and Ill use that if I find it). Then Ill use a couple more tees or the 4 way above the level of the sinks overflow and I was planning on keeping it sloped towards each fixture but honestly I feel like it should make no difference. how soon can I drop the 4" to 2" before coming out the roof? I also want to bring the kitchen sink vent about 16 feet over and tie in for a couple reasons. I only want to have to break through the roof once (would go 3" if I had to because of number of fixtures the vent services if that's a thing) and also would like no penetrations through roof on the side facing the street/driveway as you pull up. any issues with my plans? thanks in advance and you'll probably see a lot of me around here for a while. redoing my entire house and try to find what I can myself but will need to clarify things like this and make sure I understand what I am reading. also nothing will be done with any inspections/code requirements because its all homeowner DIY but I would like to do it as "correctly" as I can.