Ok this is where my lack of experience really shines through...

This is one detail that I haven't found addressed anywhere...

I have to mount some plastic (cpvc) pipe on a concrete block wall like the drawing below. For simplicity, I would like to prefab the pipe on the bench and then mount it to the wall. However I am concerned that the pipe will not sit flush with the wall...either because the wall is not flat or my prefabed pipe is not 'flat'. So if the wall and pipe system do not 'match', either point A or D will be off the wall. So I could...

1. Force the pipe to the wall with pipe straps...but they say not to strain the pipe. (The pipe will not actually touch the wall. I bought some pipe straps that keep the plastic pipe off the wall a little.)[i93.photobucket.com]
2. Tighten the pipe straps enough so they're snug to the pipe but not snug to the wall. (I don't like this because partially tightened screws tend to work their way loose.
3. Put spacers (like washers) under the pipe straps so I can tighten them down good to the wall without straining the pipe.
4. I realize the plastic pipe is flexible, but over a short run it is quite stiff.
5. I could mount the pipe on the wall piece by piece, but then I got to fight the wall the whole time being careful not to contaminate my primer or cement with the crap on the block wall. Also, might be hard getting my dauber of primer and cement between wall and pipe, especially if pipe is short and I can't flex it away from wall. Also, while cementing a fitting facing up, like elbow 'C' it would be very easy to pool a bunch of cement inside the fitting...a no-no I hear.
6. I could dry fit the whole assembly and put it on the wall...and twist each piece until everything is flush with the wall. And, then with a felt tip marker write a line on each fitting/pipe so I can dissemble it and glue it back at the same angle....but, I tried that while soldering copper pipe and it is just too inaccurate...can't get the same angle back. I guess the felt tip marker is too wide for any accuracy.

Sorry, if I am overthinking this, but I had to get it off my chest.


Ok, here is a mock up of the 3/4" cpvc pipe I plan to use...it's not to scale.[i93.photobucket.com]

And the red line in this photo shows the route for the pipe in my kitchen. The pipe will drop down from the attic, go behind the dishwasher and feed the drop elbow/stop valve.[i93.photobucket.com]



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if you are really being fussy, you can use a handful of 'clic' hangers. place them on the wall, assemble your pipe piece by piece and clic each section into place as you work along.
if the pipe is too far off the wall because of these hangers, just use method 6 and work carefully. BTW, clic hangers can be had for alot less than shown on that site.
[www.downwindmarine.com]

If you assemble it on the floor, it WILL be just as straight as it will be on the wall.

I am not a plumber, but I would still assemble it piece by piece instead of prefab the whole thing.

If you do prefab the whole thing, I bet you would have trouble sliding the horizontal leg in from outside the cabinet to the position inside the sink base while the vertical piece is in the way...you would end up having to "flex" the pieces way more than you would if you do it as you go.

If your primary concern is not wanting to touch the primer/cement applicator on the concrete wall, there are two ways to minimize that. First, by ensuring the new piece to be added is pipe, and the piece already fixed to the wall has a fitting. By doing that, the applicator will only need to rim along the inside of your fitting, and will not touch the wall. On the pipe side, since you are holding it in your hand, it will not touch the wall either. That means each new piece of pipe you add, you attach the downstream fitting (elbow, coupling, whatever) FIRST, once it goes on, then it's another female end on the wall. Second, if you do end up with a male end on the wall, just use a shim and wedge the pipe outward a little to give you the clearance you need, a shim with a small deflection two feet back will give you a good inch where you need to attach a new fitting.

But why not just use a single piece of pex and eliminate all the joints and hassle?

Not a big fan of CPVC piping unless for the T and P coming off a water heater.
As suggested....use quite possibly one single stick of 1/2 PEX pipe with none or very few joints. I do realize that most people do not have tools to work with PEX...either crimp or expanding methods BUT if I were doing this CPVC would not be even considered.



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