As part of replacing the floor joists, we had to remove the sub-flooring in what turned out to be about an 8’x10′ plot of the addition. One of the boons of peeling back the floor is immediate access to the pipes. We took advantage of the situation to move around our drainage system. When we got the house, the 1st floor had a kitchen, half bathroom, and laundry room. This meant a kitchen sink, bathroom sink and toilet, washer hook up and wash basin. I’ve mentioned in the past that all the copper was pulled out of the house. This is mostly true. The copper in the walls is still there (and will save us a lot of headache running pipes to the 2nd floor). But what is completely intact is the pvc drains. Our remodel calls for moving the kitchen sink over to make room for a pocket door, moving the bathroom and laundry, and adding a shower. The good news is this puts us at +1 drains based. The bad news is none of the new drains are in the same place as the old drains so the pipes have to be reconfigured.
I learned a lot of really neat things about plumbing on this project. A home DWV (Drain – Waste – Vent) system isn’t just a hole you dump things down. It’s an intricate, logical system of forces and paths. One of the books I’ve read had a really nice line that said something to the effect of an apprentice plumber will learn all the functions of the job in their first year, but it’ll be another three years or so until they learn and understand all the codes for the complicated sistuations that can arise with a plumbing system. This is because your drainage isn’t just made up of downward flowing drain pipes, but also upward flowing vent pipes. I don’t think I understand the physics well enough to properly explain it, but think of it like this…have you ever poured anything out of a bottle and gotten that “glug glug glug” reaction? Some of your milk or oil or soda will come out, and then an air bubble will go in. But if you poor slowly, you’ll get a smooth flowing waterfall. Likewise, if you punch a hole in the other end of the can, your liquid will rush out without the glugs. This same process happens in your pipes. So you have to provide access for air to interact with with your plumbing system. In addition to the flow of air, you have to provide ventilation for sewer gas (the noxious gases waste products give off) that exists in most any drainage system. All this amounts to having to figure out not only how you’re going to get your liquids down into the sewer, but also your vents up into the air.
For our remodel, the process first involved identifying and tracking where all the pipes went. Every fixture needs to be vented. It’s potentially possible to vent multiple fixtures off the same line and to “wet vent” fixtures, but the design and inner workings of such things are beyond my knowledge. Luckily, for most home projects, the ideas, designs, and codes are pretty straight forward. It’s when you’re plumbing a public bathroom, swimming pool, or up and down an apartment building that things get really heady. Still it took a few days of reading and studying both what was there and what I wanted to be there in order to figure it all out. It also doesn’t help that not all of our plumbing is up to code. There’s a certain amount of faith on my part that some of these pipes that disappear into the walls are what they appear to be. We’ll find out eventually, I suppose. Moving the kitchen sink was the easiest job. It just involves cutting some pipes and reattaching them. The bigger challenge was figuring out how to position everything for the bathroom shower and toilet. Normally pipes have to drop 1/4″ per linear foot for span. Importantly, this is a range, not a minimum. You don’t want your pipes to have a dramatically steeper pitch than that as it can cause the water to flow faster than the solids it might be carrying (causing clogs). Here’s my solution: 1) The toilet and shower drain into the main stack and I’ll tie the two vent pipes together and then into the pipe that previously vented the old bathroom sink. The new bathroom sink will grab the plumbing used for the wash basin. The washer hook ups will need to all be moved over about 3 feet into the new laundry room, which should involve extending that pipe and adding new hook ups. To make this all work, I do need to get up into the 2nd floor bathroom and tie that bathroom sink directly into the sewer stack that runs behind the toilet there. I’m kind of hoping this isn’t more complicated than it sounds.
The other cool thing I learned about in this process was working with PVC. I had it in the back of my mind that it was easy (or at least easier than working with metal), but I didn’t exactly know what I was going to be doing. Now that I’ve done it, I can confess that it’s both really easy and kind of fun. The essential thing to know is that you can’t unseal or remove a PVC joint. Once they’ve been glued together, it’s stuck forever. But luckily, you can quite easily cut plastic pipe with a hacksaw or sawzall. Me and my trusty sawzall made short work of the existing pipes. From there, you cut or file down the rough ends and assemble your new system of pipes, bends, couplers, and t-junctions. Once you have a correct assembly fitted together “dry”, you start gluing. PVC glue comes in two parts: a primer (ours is bright purple, but color varies) and a cement. This two part process chemically bonds the plastic by essentially melting and fusing the two pipes making a water tight seal. It’s a lot like tinker toys. After everything is properly glued together, give it some time to cure (on a hot day, it takes a few hours, on a freezing day like when we put it in, who knows?). Then be sure to properly strap all your pipes so they don’t move or you could rip something loose.
When people think about remodeling bathrooms, there’s always this line between if you need to move fixtures or not. I now understand what’s at stake in that kind of decision. But, while it’s not nothing, it’s also not so scary that you should be worried about doing it yourself. Anything can be done with enough patience and gumption.