Need advice here. I’m new to sweating copper pipe, but know that water will make any sweat fail. When doing some joints I was careful to make sure the flux had “boiled” out of the joint before hitting with solder. When done the joint was black, and I suspect I over heated and don’t have a solid joint. No leaks, but ... I treated the flux like water, when I think I should have not worried about the boiling flux and just hit the joint with solder when the solder melted. Is this best a redo before I close up the wall, or just go forward since the joints are working now? Any comments or advice is appreciated.

We are remodeling a 7x10 bathroom and need to re-route the plumbing drains for the new configuration. At this point the final configuration will be determined by the drains and vents required for a free standing tub, toilet and sink. The existing constraints include log walls which cannot have any plumbing, a single internal wall which holds the vent stack that continues through the roof, maintaining entry and exit points for existing 3 inch line. In addition to the vent stack, I also plan to use the internal wall for the tub filler. All other plumbing will be in the existing crawl space which will require putting p traps for both the tub and the sink below the sub-floor (I know not allowed). The previous pedestal sink had the p trap below the sub-floor and we never had any problems. The entire crawl space is accessible with plenty of room for proper slope. Please look at the initial design and provide any recommendations. The biggest challenge is venting each fixture. I really wanted to flip flop the vanity with the toilet but thought it would be difficult to vent the toilet in that location. The tool I am using seems to think it is ok to run horizontal vents to the stack. I'm sure this is not optimal. Also the tool refuses to run a vent to the sink. Our kitchen sink has an Air Admittance Valve which works well so I guess we could do the same but would prefer vent to the stack if possible. Any recommendations would be appreciated.