Fitting pre-fab shower to basement rough-in

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Old 04-21-13, 02:41 PM
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Fitting pre-fab shower to basement rough-in

Hi all,

Thanks in advance for any help / guidance / advice you can provide.

We live in a 2 1/2 year old townhome that we bought from the builder. We opted to have a 3-piece basement bathroom roughed in, and now I'm finishing that bathroom.

I'm concerned that the shower drain is not going to line up with any pre-fab acrylic showers that I might buy. It's located 10 1/2" from one wall, and 18" from the other. I've taken a picture of it and drawn a simple diagram showing the measurements.

If it doesn't match any shower pans, I've come up with three options myself - but let me know what you think!

1) Raise the shower off the ground a bit, so that I can use two 90 degree turns under the shower to line the drain up. The distance from the cement floor to the floor joists is 90" (there is no flooring installed yet and no drywall on the ceiling yet), so for, e.g., a 78" high shower, there's a bit of leeway, I think.

2) If there's a shower pan with the drain 10 1/2" or less from the wall on either side, just build out the wall that is 18" away - however, I have to be careful as there's not much wiggle room on the toilet side of the shower (i.e., I can't build it out too far before it collides with the toilet).

3) Build a custom shower pan and make the whole thing a tiled shower. I'm wary of this because of the extra time investment it'd require.

Again, thanks for any help you can provide. If you want any more details or pictures, let me know!
 
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Old 04-21-13, 02:47 PM
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Welcome to the forums! The 18" dimension may work for a 36" square shower. How long is your shower pan going to be? It is a 2" drain pipe, right? Gotta be for a shower..

Door #3.

The other option would be to jack hammer up the pan area and move the drain to where you want it to be to match your pan. It is done every day and presents no structural problems. You don't want to do door #1, period.
 
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Old 04-21-13, 03:38 PM
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Thanks for the quick reply, chandler!

It is a 2" drain pipe, so I'm good there. I haven't chosen a shower pan yet, so I'm flexible on the length. If I can find one that fits the drain, I'll be happy!

The 10 1/2" clearance seems to be the trouble. I'll keep looking at pre-fab showers to see if any have the drain close enough to the wall. Otherwise, I'll either 1) jack hammer up the pan area, as you suggested, and place the drain exactly where it needs to be for whatever shower I choose; or, 2) do a tile shower instead, and custom fit the pan to the drain.

Any other suggestions are welcome!
 
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Old 04-21-13, 04:40 PM
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Or another option (and it seems that the drain may have been positioned to fit something like this instead) would be to put in a pre-fab shower + tub combo, like this: Mirolin Industries Corporation
 
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Old 04-21-13, 05:10 PM
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Yet another option I've found - showers with "above-the-floor rough", where there's a few inches of clearance built in beneath the shower pan to let you re-route the drain pipe: Showers - Unique Feature Above-the-floor Rough (AFR) - MAAX
 
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Old 04-21-13, 05:23 PM
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Most of the showers you refer to are using an 8 5/8" setback for the drain, so it may not work on yours. It won't be too bad making the corrections. I would get the pan I liked and adjust the drain. It sounds daunting, but it isn't.
 
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Old 04-21-13, 05:27 PM
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Yeah, after looking at all the options, that seems like the best. Might as well get what we want.

And you're right, it sounds very daunting! I'm likely going to have a plumber in to run the water lines for the bathroom, so I'll ask about including that as part of the job.

In retrospect, I should've asked the builder to make sure the drain was located for a standard corner shower (most of which seem to require the drain to be 12" from both walls). Lesson learned for next time!
 
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Old 04-22-13, 05:30 AM
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I know there are differences between regions and between contractors, but any chance you'd know what the ballpark cost of a job like that would be? (i.e., the cost of digging up the floor, moving the drain, and repouring the concrete)
 
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Old 04-22-13, 01:54 PM
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Really no idea, but rent an SDS hammer for $40, cut the floor out, carry it out in buckets, dig the dirt down and reassign your piping to where you want it and fill the hole partially with gravel and top it with concrete, smoothing it out like a birthday cake. May take you 4 or 5 hours. I don't know what plumbers make in your area, but it would seem $400 should do it, but that's a total WAG.
 
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Old 04-23-13, 09:49 AM
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Thanks for all the advice Chandler - I really appreciate it.

I'm having trouble figuring out how much floor to dig up. I only need to relocate the drain by about 6 1/2" - would a 12 square inch area around the drain be enough?

Or will I have to dig out above the pipe after it takes a 90 degree turn beneath the concrete slab (i.e., where it becomes horizontal)? I don't see how I'd move the vertical portion without moving the horizontal portion...

Also - I've read that some people don't repour the concrete after doing something like this. Instead, they leave a 12 square inch "box" around the drain, that's empty until you reach the gravel fill, so that you have some wiggle room when you go to install the shower above it. Not sure what this "box" is made of though...
 
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Old 04-23-13, 12:21 PM
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After doing some more reading, it looks like I need to:

1) Dig up concrete and dig out dirt to expose the P trap.
2) Extend the horizontal pipe before the P trap to reach the new location (and use a 1/4 or 1/8 elbow to change direction, if necessary - but apparently not a 90 degree elbow, those are verboten).
3) Reattach the P trap and the vertical pipe coming out of the floor.
4) Build a 12" by 12" form to go around the vertical pipe, so that the poured concrete will leave a "box" around the vertical pipe and the P trap.
5) Repour the concrete and install the shower.

Does that make sense?

And if it turns out I only need to break up a couple square feet of concrete, do you think I could manage it with just a sledge hammer? If so, should I still score around the area to break up with a circular saw first? I don't care if the broken-up area is clean around the edges, as this will be hidden. But I don't want to risk creating a bunch of cracks through my foundation (I've read that can happen if you don't score the concrete first).

If I can avoid the mess of dust by using a sledge and elbow grease, might be worth the trade-off...
 
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Old 04-23-13, 05:06 PM
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Circle saw and sledge hammer may work for you. You may encounter fence wire, so you should have a grinder handy to take care of that, too. The 12 x 12 box is usually for tubs, but it depends on the structural stability of your insert as to whether it will sufficiently span and support itself over such an opening. At worst, gravel and a skim coat (1" or so) of concrete wouldn't hurt and can be broken out later if needed.
 
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Old 04-25-13, 06:08 AM
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Just an update - I've bought a blade for my circular saw that's meant for cutting concrete. In the next few days, I'm going to drape plastic sheeting / tarps around the area where I'm cutting (to contain the dust) and score around the section of concrete I want to break up. Then I'll smash it apart with a sledge.

I'll take pictures as I go and post them when I'm finished. Chandler - thanks for your guidance, much appreciated!
 
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Old 04-25-13, 06:32 AM
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What part of Canada are you in?
I'm concerned your circular saw isn't going to be up for the job.

I've had to do a similar job (helped out actually, and will be doing this myself in the near future) and found a jack hammer is the way to go. Cutting the hole would make a nice clean cut, but the mess and issues with concrete depth (being too much for the saw, or inconsistant) will cause more issues then it's worth, particularly something you're going to fill and hide anyway.

Also, be aware that the scrap concrete is going to be very heavy, so have good buckets or other means of transporting the scrap in place.
 
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Old 04-25-13, 06:51 AM
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Hi Mike - thanks for the input! I'm in Ottawa.

I was hoping that, because of the small scale of the job, I'd be able to get away with using my circular saw - not necessarily to cut all the way through the slab, but at least to score the concrete before smashing with the sledgehammer.

In total, it's only a few square feet of concrete that I need to tear up.

Speaking of the scrap concrete - I assume this isn't something I can throw out at the curb on garbage day. Any recommendations on how / where to dispose of it?
 
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Old 04-25-13, 07:07 AM
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So you are a few km south east of me.

Most circular saws won't have the power or RPM to make the cut.
scoring and smashing doesn't always work out, particularly if there is rebar or anything else.
For the scrap concrete, a few square feet of concrete is a lot when busted up, trust me. I've been off and on working on removing a 3'x3'x3' chunk of concrete in my basement that is full of large rocks (which shouldn't be an issue for you). I didn't think it would be much, but It does result in a lot of scrap and weight.

Do dispose of the scrap concrete... if it's straight concrete/rock/dirt, you may be able to provide it as fill to anyone looking for free fill. The more likely option will be a trip to the dump. Road side pickup will not be an option.
Check with your local waste management to see what the costs or tipping fees will be like. In Sudbury, it was free for the first 100km (per calendar week) and a couple dollars per 100km above the first 100km. When I say a couple dollars, less then $10 if i remember correctly.
 

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Old 04-25-13, 07:44 AM
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All good points. I did a little reading on my circular saw (a Milwaukee "HEAVY-DUTY CIRCULAR SAW WITH TILT-LOKô HANDLE"). In the operator's manual, on page 10, it gives guidelines for masonry cutting:

"When cutting masonry, use a diamond blade. Make successive passes at depths of less than 1/4" to achieve the desired depth. Cutting at a depth of
more than 1/4" will damage wheel. Unplug the tool and frequently clean dust from air vents and guards."

Also, it advises, "Only use accessories with maximum speed rating at least as high as nameplate RPM of tool." So I'll double-check that against the blade. (The saw's "15 Amp motor delivers up to 3.25 HP and 5,800 RPM.")

The area I'm cutting up is 2' by 1', at most. I'm not looking forward to carrying all that concrete out, but I shouldn't have any issues with that.
 
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Old 04-28-13, 05:58 PM
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I've outlined in red the area I plan to cut up in this picture.

The solid line is the direction of the existing horizontal drain; the dotted line is my proposed redirection of the horizontal pipe. I'm hoping I can make the new turn in the pipe a 45-degree turn.

Do you think this'll work? Any gotchas I should watch out for?

On another note - I'd said earlier in this thread that the drain pipe is 2". Turns out, that's from outside edge to outside edge. Really, it's only a 1 1/2" pipe. However, from what I've read, in Ontario the code for a shower with only one head is 1 1/2" so I think I'm good...
 
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Old 04-29-13, 03:22 AM
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I think you have a plan. I'm not sure of the north-of-the-border codes, but I believe it has been mentioned here before about the 1 1/2" shower drain. Mike may have more on that part, so hang in there.
 
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Old 04-29-13, 04:07 AM
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I haven't gotten that far in my latest project to confirm the code on shower drains.
I can however confirm that both of my tub/shower drains are 1 1/2" (installed by a previous owner of the home) and my old house was the same.
I'll be roughing in the bathroom for the third floor this summer and the one for the basement next summer.
 
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