View Full Version : Single person shower to double person shower

07-05-2011, 08:28 AM
I need to rip out my shower and re tile it. I was thinking of making it bigger and adding a second shower head and separate control.

I was just planning to extend the pipes and T out to the new shower valve. I don't think there is an issue with any of that as far as code, but if there is could someone tell me.

Where I thought I may have the issue is with the drain. I was just planning on using the existing drain that is there, maybe move it a bit if I could to the centre so it's easier for my tile guy to mortar the floor slope. Will the existing drain be big enough and be able to handle the extra flow from the double tap? Is there actually any extra flow considering I am just branching off an existing half inch line? The house is pretty new 5 years or so, so the ABS is 1.5 inch.

I am in Burlington Ontario by the way.

Also, when moving the drain, it would be a no-no to notch out the floor joists right? I wouldn't think I should do it, but if I am allowed, and if it makes for a nice centred drain one joist over I would consider it.

07-05-2011, 10:52 AM
1. Two valves mean TWICE as much water, regardless of the pipe size to the valves.
2. The existing drain should handle the added flow, if it IS the minimum 2". If it is 1 1/2", then it was NEVER to code and will be too small.
3. It is NEVER a "good" idea to notch joist, but if you decide to drill holes in them, there are strict specifications as to the size and WHERE it can be done.

07-05-2011, 07:01 PM
In the USA, a 2" drain for a shower has been code for awhile. Not sure about Canada. Bigger is better. It's not great to be in standing water that can happen if the drain is too small or restricted. But, 1.5" should work. The reason they went bigger is to take care of those what-if situations so that you don't overflow the curb of the shower if you say drop the washcloth or stand on the drain cover and don't notice right away...the bigger drain can clear the backup faster.

07-05-2011, 07:28 PM
I am trying to remember what the drain was in my old house, built in 1995 or so, when I changed the tub to a stand up shower. I believe it was only 1.5 inch. Actually thinking carefully about it, I am sure that it was.

When did the code change? If that is the case, and it is only 1.5 inch then how would I go about changing it? I suppose I would have to redo the entire drain all the way to the 3 inch stack? Does the vent need to be 2" as well?

07-05-2011, 11:20 PM
The vent can stay the same size.

Two shower valves on 1/2" pipe is fine.
Don't notch the joists. You can drill them if you leave 2" between the hole and the edge.

07-06-2011, 05:24 AM
The house is pretty new 5 years or so, so the ABS is 1.5 inch.

I am in Burlington Ontario by the way...

Code in Ontario requires 2" for a shower drain. I don't know how it passed inspection.

07-06-2011, 05:55 AM
I cannot remember ANY time when a 1 1/2" drain was acceptable for a shower, (I have never seen any shower drain with a 1 1/2" outlet), and that goes back to the 50s.

07-06-2011, 06:43 AM
I would upgrade that drain to a 2" line straight back to the stack. Like Terry mentioned no notching of the floor joists and keep your holes with 2" (1 7/8") top and bottom. These numbers are for a 2"x10" floor joist.

The largest hole you can drill through your floor joist is 2 3/8" for a 2"x10" framing member. I found a good blog site from a structural engineer - check out his site (http://woodengineering.blogspot.com/). You will notice as well not to drill through the shear and movement critical areas.


07-06-2011, 07:42 AM
In my old place, it was a bathtub I ripped out and turned into a stand up shower. Would a tub have been 1.5" but a stand alone shower different? That would be an oops now, but the house is sold. Nothing I can do. I know for a fact though that when I ripped it out, and cut the drain, I just redid the fixed trap, and moved the drain slightly and I never bought 2" pipe it was all 1.5" and fit back together perfectly so I wasn't dreaming.

So no notching of the joists then. But I can drill a hold big enough for a 2" abs pipe as long as I leave clearance top and bottom if I am understanding you correctly. I will have a look at the site. Thanks.

So redoing the 1.5" line all the way to the stack could definately require some major wall demolition. But neccessary to pass code.

07-06-2011, 08:23 AM
I need to rip out my shower and re tile it. I was thinking of making it bigger and adding a second shower head and separate control.

Adding a second shower head will take all the fun out of 2 people showering together.

I do believe. But then again I am in Texas, where Southern girls enjoy it.

Sorry folks, I just speak the truth.


07-06-2011, 09:57 AM
The limitations on where and how big you can drill through a joist include where vertically, and also how close to the ends it can be done. A plank joist gets most of its strength from the continuous top and bottom portions, and the middle supports those edges (just like in an i-beam). You don't want to drill real close to the ends, as instead of shear and compression along the length, it is mostly in compression vertically, and a hole there weakens it more.

07-06-2011, 10:51 AM
code once allowed 1.5" diameter for showers.
It has been discussed before in this forum.

In Canada, I believe it is still permitted. 1.5" pipe.

At any rate, the LENGTH of the 1.5" section of pipe is a key number to know before anyone prescribes a total re-do. If it's a foot or two in length until the stack, the pipe will safely carry the shower drain water to the stack.

I believe they still use 1.5" pipe for washing machine standpipes in Canada. They have the same Kenmore machines as the US has. And all the other brands too. They are not restricted to using little machines only. Any washing machine that can be sold in the US can be sold in Canada. I'd like to point out that there seems to be NO horde of Canadians griping their washing machines standpipes "can't take it." Total silence. Nobody is complaining. ((!!??!!!).

Ultimately, a 2" pipe allows greater distances (self-venting). In Canada houses are generally small or medium size. The need for a 2" pipe is for DISTANCE to the stack, not because of the amount of water hitting the drain grate or being pumped into the opening of the washer standpipe.

By the way:
Tubs still have 1.5" pipe as their accepted normal prescribed size.

p.s. the thread starter person may be mistaken. It may be 2" in his house and he cannot see the difference.

I hope this helps.

07-06-2011, 11:26 AM
In Canada, I believe it is still permitted. 1.5" pipe...
I'd like to see a code citation of that. Back in '98 when I did the plumbing in my home, the inspector insisted on 2".

07-06-2011, 11:31 AM
geniescience is correct that I have not actually lifted the drain on my existing shower to see weather it was 1.5 inch or 2 inch. What I do know is that at my last home, the drains coming from the tubs were definately 1.5 inch abs. Seeing as this already is a stand alone shower, I suspect that when I tear it out, I will likely see a 2 inch drain if it is in fact the code now.

Thank you all for the info.

I can also atest to the fact that our washer drain lines are in fact 1.5 inch, and this is true for all the new houses I have been to and helped friends install washers. Never had any issues with any of the new front loaders that drain large amounts of water very quickly.

Is there somewhere I can look up the code in Ontario for the showers? I know the fancy drains all come in a 2" abs size. My guess is that this is the reason.

07-06-2011, 03:29 PM
One more quick question. I saw them cover this on Holmes Inspection show.

A rain shower from the ceiling. The two options are to build a bulkhead 6 or 8 inches, or whatever and run the plumbing through that, or to go through the attic and keep the ceiling height the same. They went through the attic in the show, and the obvious problem with that is freezing of the pipes. What they decided to do was box it in with wood up top and put more insulation around it. I would assume that meets code if Mike Holmes did it since he is very by the book. Anyone have any experience with this.

And this would lead to another question, what would be the rules for moving the plumbing from the wall it is currently on (inside wall), to an outside wall. Sounds like a no no but I'd rather have some input. What about a garage wall? Is that any different?

07-06-2011, 03:43 PM
Yes, box it in within the attic space so that there is no insulation between the ceiling and the pipe and heap the insulation on top of the box.

07-06-2011, 04:16 PM
As long as the pipe is run close to the ceiling and there's a bunch of insulation on top (and, there's no major air leaks), the pipe shouldn't freeze as long as the heat in the house stays on. Plus, if you slope it slightly, the run to the shower head doesn't need to have standing water in it, if sloped to the head, it will (eventually) drain out and then there's no water in there to freeze in the first place. If you put in a 'toe tester' (essentially a tub spout) the riser pipe would drain, and you can purge the cold out before you step into the shower.

07-06-2011, 06:27 PM
The first thing you have to understand about insulation is that it does NOT prevent ANYTHING. All it does is slow down the transfer of heat from one surface to another. IF left alone long enough then one surface, namely your pipe, will reach ambient temperature, and if that is below freezing the pipe WILL freeze, regadless of how much insulation is around it, and at that point the insulation may contain the coldness so the pipe takes longer to thaw out..

07-07-2011, 06:22 AM
I don't know about Southern Girls (actually I do) but I can tell you up North we like to stay warm in the shower. My wife takes forever to rinse her hair and I get stuck in the cold. Adding a second shower head would be great.

We plan on two shower heads when we do our en-suite shower...