I always feel like I should be faster at plumbing than I am. In theory it’s simple: For the drain side of things all you need to know is that water flows downhill, the pipes need to be big enough for what they’re transporting, and things should be vented appropriately. On the supply side of things the pipes either need to be big enough or short enough so the cumulative drop in pressure doesn’t exceed the flow rate of your appliances. It’s not exactly rocket science – at least in a tiny house build – but nevertheless a lack of familiarity and dexterity with all the pieces combined with a moderate degree of disorganization can really slow things down.
A big consideration with any plumbing task is sequencing so you don’t literally back yourself into a corner where you can’t crimp or glue a fitting.
Before I start running my pex I make myself a little toolbox with everything I need and ONLY those things so I can easily put my hands on the next piece or tool without having to move or get up.
Additional things I’ve found helpful is to always buy at least 30% more fittings than you need and return the ones you don’t use. If you’re not sure what’s going to be on the end of the pipe leave it a bit long. Be careful nailing things onto the outside of the house afterwards so you don’t accidentally puncture the pipe. Use nail plates on the inside for the same reason. Don’t crimp on the inside of a 90° elbow because it will block the other side from being able to slide on all the way. Wherever possible leave space between fittings in case you need to splice another piece in to repair a mistake or add more plumbing later. If you’re plumbing in an application where your flow might be limited you can get a little better flow out of the metal fittings that have a larger internal diameter compared to the plastic ones before having to step up to three-quarter inch pipe. Consider adding a low point drains to the system and sloping all pipes towards it so you can drain the house if you’re leaving it in a cold area unattended.
– Brian
