It's wet, it's dirty....get it outta here!
Having the septic system installed is a key motivator to working on the drain system in the garage-apartment project. Just the thought that we could possibly set one of the toilets temporarily and flush it with a 5 gallon bucket of pond water is a considerable upgrade for our LNP lifestyle. Life with the porta-potti has been OK, I guess, but after 2 years of transporting that thing back and forth to dump it and re-fill the fresh water has definitely worn an uninvited groove into our lives. Don't get me wrong; we both really appreciate it when we need it, but the glub-glub-glub combined with the splish-splash when I have to empty it at home kinda sucks. Let's kick open the door to a bunch of PVC pipe and glue!
I've worked with PVC pipe many times before; mostly small to medium size jobs. Besides working with wood, I would have to say that PVC pipe is right up there for ease of handling, fabrication, and assembly. Moreover, it's pretty darned cheap. I won't say that this next phase is gonna be cake, but I'm not intimidated by it, either. The biggest issues will be more logistical. Stuff like "what size pipe" along with "how will I get it from here to there" further complicated by "don't forget that this thing must run downhill at a very specfic rate without running out of installation room". The "what size?" thing is answered by the multitude of plumbing websites that have charts and graphs. They're out there and a little studying makes it relatively easy to understand. The "how will I get it from here to there" combines with "the specific slope" thing as the biggest part of the equation. As I always say, a pro would have this thing knocked out in a couple of days. For me, it takes a couple of weekends. Without completely tipping my hand, I will say up front that it all worked out pretty good....so here we go.
We have the following fixtures to consider for drains:
2 bath vanities
1 bath/shower unit
The last two (utility sink and wash machine) are both going to be on the first floor, so they are addressed as a separate headache...er, I mean project. All the other items (#1 - #4) are on the second floor living space and each will be a math equation. Why?...because they all feed into one main 3" PVC drain that runs down the center of the 2nd floor framing. The slope of each fixture sets it that much higher than the 3" main and each must be calculated to tie in at just the right height without running out of room within the framing. The good news is that they are all located in close proximity to each other, so there will be a lot of connecting at one end of the system, then a long ride to the other end of the structure to get to the main soil pipe that exits the structure. The real blessing, though, goes back to the beginning when we were planning the framing for the second floor....tell ya why....
You may have seen this pic already. It goes back to framing for the second floor.
The advantage we gained is illustrated with the top note; the drain pipe, loosely staged. Those engineered I-joists that frame the 2nd floor are 16" tall. The factory cut all those holes in them to allow for stuff exactly like the drains we are going to assemble. The hole is pretty big at 10" diameter and all the holes in all the I-joists line up from one end to the other. A properly sloped drain will drop 1/4" for every 12" of horizontal run. The outside diameter of a 3" PVC pipe is 3-1/2". Let's do the quick math: 10" hole - 3-1/2" pipe = 6-1/2" of available space inside the center of the hole. This translates to 6-1/2" of possible elevation change as the pipe runs along thru each I-joist down the center of the building. Using the 1/4" per 12" slope formula, this allows 26 feet of travel before we run out of hole space to drop the elevation. Based on the location of the furthest fixture at one end as it compares to the location where that 3" main drain pipe drops down below the I-joists, 26 feet is more than enough run. For this facet of the job, we are in good shape. Bring it!
The next headache is another logistical thing, but this one is self-inflicted. I built a structure with a first floor ceiling that is 9-1/2 feet tall. All this is going to be ladder work. It's gonna go slow. I start by estimating the height of the 3" main at the bays where the drains from each fixture is going to come over and join it. Then, it becomes another "elevation change" math equation as I calculate if there is still enough room within the individual bays of the ceiling framing to continue that same, consistent 1/4" slope thing all the way to the location of the target fixture. Once again, choosing the 16" tall I-joists yields great results and the height is there for all of the fixtures to run at a good slope to the main drain. Let's take a look. Be careful and don't get dizzy...
DRAIN COMING IN FROM THE GUEST TOILET
DRAIN COMING IN FROM THE GUEST VANITY
KITCHEN SINK DRAIN (the furthest drain and the furthest end of the 3" main)
THE DRAINS FOR THE TOILET AND TUB/SHOWER (before the tub was installed and hooked up)
AND AFTER INSTALLING THE TUB/SHOWER AND HOOKING ALL THE DRAINS AND VENTS
A BIT OF PIPE AND A WHOLE BUNCH OF WIRE
As this main runs to the other end of the building, it has to drop down below the framing a bit earlier than I would have liked. Basically, it hits a brick wall that we call the double lam beam.
We cannot cut a hole thru that thick beam for fear of severe structural integrity compromise. As a result, we must route around it....and there really is only one way to go. Shortly later, we hook it up and send it on it's way to exit the building.
Since the ceiling height is 9-1/2 feet, this exposed pipe is well above being a hinderance. No, it ain't a perfect installation, but it is mechanically sound and works. Let's take a quick look at that managerie' of pipes below the stairs....whassup wit dat?
Since I am doing all this drain pipe plumbing, and since we have this dead space underneath the stairs, now would be a good time to add the pipe necessary to facilitate installation of a utility tub and the option of a washing machine hookup.
We included a 4" cleanout with a plug that will provide quick access to rod out the main soil pipe from this point and all the way to the septic tank....one straight shot.
Let's take a look at the drain hookups as they appear upstairs
And finally, the short-range goal that really kept me cuttin' and gluin' all that stinkin' PVC...
We set one section of cement board for the tile surface that will eventually land in the guest bath. Adding some 3/8" plywood elevates the toilet the the correct height and we set the stool onto the wax ring. It's my job to make sure that there's always a bucket of "flush water". After a couple of wet trial runs, we are content that this upgrade is ready for action.
The drain vents
Installing the vent for all this drain stuff was a little easier, though not much. Once again, most of it was ladder work. Also, like the drains, the goal is to tie everything together into one tidy bundle and send it out of the building....except this time it goes thru a hole in the roof.
Sometime last summer, we cut the hole thru the metal roof and installed the rubber boot that will receive the main drain vent as it exits the structure.
We slipped in a short pc of 4" PVC pipe that could easily be removed when the time comes to install the real, permanent vent pipe. Since we had to draw the pipe blank downward to remove it from the inside (I ain't goin' back up on that roof if I can help it at all), we couldn't put a cap on top of the pipe cuz it wouldn't slip thru the rubber boot. Hmmm....what to do. I know, let's take a cheap plastic bucket and put an eye bolt into the bottom of the bucket. Then we can put a bungee cord up thru the inside of the pipe and grab the eye bolt to hold the bucket on. When the time comes to remove the pipe, we unhook the bungee cord and use a broom stick to push off the bucket as it rolls off of the roof. Then, slip the pipe blank back down thru the hole and we're good ta go.
Well, that time DID come and I worked on tying all the drain vents together to meet at that hole in the roof. This work carries the same need for a positive slope. Since rain can get into the roof vent pipe, it has to have a place to go. In fact, it is presumed that water could feasibly get into any section of the vent pipe, so every inch of it must head downhill. By the time I got all the vents to gather in the area of the main vent stack, I actually did run out of room because of some lousy planning combined with the necessary slope. I had to invert the main vent Tee's at the main stack, just to pick up an extra inch of height. In the end, this won't have any ill effect on the system. A big-city plumbing inspector might throw a red flag...or not. Like I said; no biggie. Anyway, here ya go.
With this drain and vent work completed, we have put another milestone behind us. Being hooked up to an operative septic system is icing on the cake (ick!). On to the next project....