Moving Toilet drain drilling through floor joists

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Posted by: from Calgary
11/17/2012 at 2:56:56 PM

I have been working on a complete remodel of our master ensuite. I have the entire bathroom torn down to studs and torn up most of the floor. I want to move the toilet over a few feet but doing so means moving the drain and would have to dill holes in the floor joists.

The house was built in 1982 and it has 2x10 joists, not manufactured I-joists.

Can I drill holes through the joists without compromising the structural integrity of the floor? If so, is there something I would need to do to reinforce the drill through joists?

This project has been going on now for close to 2 yrs and my wife's patience is starting to wear thin.


I have included a picture of the open floor and need to move the drain over by 2 joists.


Calgary, AB

moving toilet drain drilling through floor joists
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Josh from Jem Contracting in Barrie
Date/Time11/17/2012 at 4:07:21 PM

I would Recommend against drilling through the floor joists. If there is room on a floor below, bulkheading is the answer.

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Brian in Calgary
Date/Time11/17/2012 at 4:14:44 PM

There really isn't any room in the ceiling below as the ceiling below is over a hallway. Sounds like I may be stuck with leaving the toilet where it is then.

Back to the drawing board to make all this stuff fit it he bathroom.

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Date/Time11/17/2012 at 4:20:41 PM

I would also not recommend drilling through the joists. In my area an inspector would not allow it at all.

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Constantine from Constantine in Toronto
Date/Time11/17/2012 at 4:40:32 PM

Do not even think to drill a hole for your toilet drain on your floor joist. The bigger hole you can drill on 2x10 it will be 1 inch and you need at least 4

Try to build some how a bulk head downstairs if it is possible.

Good luck with your project


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Date/Time11/17/2012 at 4:41:18 PM

Please expand on the picture - to the right.

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Date/Time11/17/2012 at 4:42:57 PM

If you are moving it two feet why not consider just to place it right beside the joist and you could also use an offset type of floor flange to go inside the 3" abs instead of over the outside of the abs pipe.

Never ever cut a floor joist of any type.

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Brian in Calgary
Date/Time11/17/2012 at 5:09:33 PM

Ok, enough of a response that I will just leave the toilet on that side of the room inside that floor joist.

I can move it across the room though within those joists.

Now I will still have an issue with the drain for the tub since the drain is in the centre of it. I think what I "can" do is build a "riser" for the tub and then run the drain above the floor joist to where the drain is and thus avoid cutting into any joists at all. Would just build the riser about 6" (like a deck).

What do you guys think (if you can imagine what I'm thinking).?


Moving Toilet drain drilling through floor joists
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Date/Time11/17/2012 at 6:59:00 PM

To move the toilet over with a bulkhead, it would be best to have it to the right side of the picture. Do you have room over there to make one?

Your deck idea is quite a common solution, although not very attractive most of the time. They do sell tubs with a variety of drain locations, including free standing tubs with skirts that hide to drain so it can be run anywere underneath it.

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Brian in Calgary
Date/Time11/17/2012 at 7:26:38 PM

The tub is a free standing tub with a skirt. I will have to take it out of the box to see if it has enough clearance underneath it to run the drain without having to it it on a riser.

As long as I move the toilet to the right of the photo, I can stay within the joists and not have to build a bulkhead to accommodate it. It's not the ideal layout that we had hoped, but it is still workable.

I posted another picture as well but it hasn't cleared "forum" security yet. The 2nd photo shows more of the area to the right, closer to the actual drain. This way the toilet flange will be closer to the main drain.

Stay tuned.

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Brian in Calgary
Date/Time11/17/2012 at 7:40:04 PM

Just opened up the tub and looked underneath. There is 1 3/4" clearance from the bottom of the brass tub drain to the floor clearance. Doesn't seem like there will be enough clearance under the skirt of the tub to run the drain horizontally. Sounds like I will have to build a short riser for the tub. Ugh. At least it won't have to be very high off the ground. A 2x4 platform should suffice.

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Date/Time11/17/2012 at 8:40:32 PM

Hi Brian,

Unfortunately it isn't that easy. You can not drill holes that large through the floor joist without compromising the structure. You can safely drill a hole that is no larger than 1/3 of the height of the beam, a 2 x 10 being 9 1/4" deep, you can not drill a hole large enough for 3" pipe to fit thru. Even if you could, the hole must be in the middle. this will work for one hole but not if you are drilling a series of holes. Once you slope the pipe a 1/4" per foot you wouldn't stay in the middle. The best solution would be to relocate the drain pipe from below the floor to the main stack.

Hope this helps,

Mark MacDonald

Choice Home Services

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Brian in Calgary
Date/Time11/17/2012 at 8:52:41 PM

Thanks Mark. Yes, I have given up the idea of moving the toilet across joists. I am simply going to move it laterally (if you see in the picture where the drain is). This way I will not have to cut through any joists at all. I will also have to reposition where I was going to put the tub. It's a freestanding, skirted tub with the drain it he centre. The bottom of the drain under the tub is only 1 3/4" from the floor so I will have to put the tub on a riser in order for me not to have to try to touch the joists again.

At this point I'm not about to create a bulkhead so I will have to change my plans and make it work.


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Date/Time11/18/2012 at 2:46:09 AM

Hello Brian,

Maybe there is a way to do it. Did you ever heard about wall hung toilets? You could move the the toilet pipe forward the wall underneath the wall (I guess it is not a loaded wall) go straight up and then turn left and go as far as you like to have your toilet where you want it. A bit of re-framing would be required however you would get what you want and even more. Please check out many walls hung toilet solutions here:

And even If it would be for some reason not allowed to run the waste pipe inside the wall, you still could run the pipe in front of the wall close to the floor and cover it thereafter and tile it. This solution is called: Geberit Monolith sanitary module for WCs:


3D-Tile-Design - Bertram Tasch

Maple Ridge, BC (Greater Vancouver)

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Artisan Bathrooms in Toronto
Date/Time11/18/2012 at 10:11:37 AM

Hi Brian,

I've just read the other reply posts and I disagree with posters with all due respect (we get this kind of misinformation given to clients all the time). We move these toilets regularly in our bathroom restyles by drilling through the joists. You need a 4"dia hole, given that you have 2x10 there is stiil lots of meat on joists (3"top and bottom of hole) and most of joist load is carried at top and bottom of joists, just ask a structural engineer this and they will agree.

Now you have to keep "slope" or fall of the pipe in mind so keep a short bubble level handy. I notice that you have a heat duct run in same joist cavity, is this why you are moving toilet closet flange? If not and you are wanting to move toilet to allow for different floorplan I understand.

Once you have your new location mapped out for toilet mark your joists on top to indicate drill locations you will need about .75" of fall for that distance over 32 iinches if your joists are 16"on centre. You will have to double up each joist (the full span of bathroom) you cut through, this is recommended to give additional strength and you will glue and screw or power nail new joist material on. Use PL premium polyurethane adhesive to glue joists. just dont put glue where you are going to drill hole or you will gum up your drill bit with glue. Also you will need to put solid blockers on either sides of hole between joists to tie all joists together transferring loads to additional joists. You should put peices of wood between joists anyway as you will get a better floor. Use 3' spacing. You can use 2x10pcs, this will transfer loads between joists. Builders do not install as this takes too much time but you should do this anyway, we do it on all our floors and it gives super strength to structure.

As I said if you do this and clad your floor with .75" ply you end up with a super strong "deflection free" floor. Make sure you know your roughin dimension for toilet from wall, generally use 13" from wall stud, this should give you 12" finished for the toilet roughin, however some toilets require different roughin dimensions, just verify what toilet you will be using.

Also, I cant see the vent from toilet pipe so if you are further than 5' from stack you need to vent this toilet and tie vent to stack above in attic.

Bob Beal

Artisan Bathroom


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Artisan Bathrooms in Toronto
Date/Time11/18/2012 at 10:22:10 AM

Further to my last post, you may want to consider hiring a professional to do this work that is best not left to an amateur builder or diyer. You mentioned 2years for this project? I am assuming you wish to stay married.

Hire a pro to do the difficult stuff, like a professional plumber to do the drains/venting and the electrical.

I recognize you may be quite proficient and a handy guy (maybe an engineer) but a happy wife is a happy life.

By the way we get these type of requests alll the time from wives usually where they ask us to come in and finish jobs started by well-meaning husbands or partners.

Bathroom renovations are complicated given the smallish size of the rooms involving drains, water, electrical etc. Many folks dont realize this.

I do applaud you however for taking the project on.

Bob Beal

Artisan Bathrooms


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Date/Time11/18/2012 at 11:13:40 AM

In Ontario, holes in joist must not be closer than 2 inches from the edge of joist and the hole must not exceed 2 1/4 inches in diameter or a 2X10.

Ontario is pretty much the same as National Building Code.

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Date/Time11/18/2012 at 11:29:35 AM


Your original question has generated a considerable amount interest and comments.

More to the point of ascertaining Code requirements than location of your toilet. There are specific criteria in the Code that must be followed when considering coping, coring or notching floor framing members.

Extract is from local code: Holes Drilled In Framing Members

1) Holes drilled in roof, floor or ceiling framing members shall be not larger than one-quarter the depth of the member and shall be located not less than 50 mm from the edges, unless the depth of the

member is increased by the size of the hole. Notching of Framing Members

1) Floor, roof and ceiling framing members are permitted to be notched provided the notch is located on the top of the member within half the joist depth from the edge of bearing and is not deeper than

one-third the joist depth, unless the depth of the member is increased by the size of the notch.


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Date/Time11/18/2012 at 12:17:35 PM

Hi Brian,

The simple answer is no. Raising the tub is OK but then it's harder to get into.

Dan Brown, RHI

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Date/Time11/18/2012 at 8:35:57 PM

Hi Brian, The question you asked is can you drill a hole for the toilet drain through a floor joist. The answer is no!

Secondly from the picture you have a water feed inches from the heat vent. NO! That has to be moved.

Toilet beside a heat vent. No!

Looks like you are five feet from the wall furthest away from the heat vent. I would suggestsome renovations along that wall under the floor to reroute your toilet drain.

This might seem like a big job. Well my friend it is. I suggest before you do more, you do less and call a contractor who knows the codes and has some construction background.

Other option go to school and understand what it is you are doing.

This is way more then a bathroom upgrade.

Sorry for being so blunt but you need physical help not a school lesson in how to. It has been two years and it will take at least three years for you to get the knowledge you need for this one.


Edmonton, AB.

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Brian in Calgary
Date/Time11/19/2012 at 7:57:49 AM


Thanks for your comments.

However, the current configuration of the vent, toilet and water feed in the picture were all original from when the house was built in 1982, so please don't assume that I am making these kind of bonehead decisions. I am simply trying to redo this bathroom, and in the process, I want to do it right.

I am very clear on the "though shalt not cut floor joists" principle and I will not be doing anything of the sort.

It has taken me 2 yrs because I have a very busy work schedule, an active lifestyle and was quoted $35k for a contractor to do this for me. With 2 kids in university, I don't have that kind of money to pay someone to do this for me.

I am certainly hiring a plumber and electrician to come in to do all that certifiable stuff as I understand the importance around that. I have done all the demolition and am very good with doing tile and drywall myself.

Thanks to everyone for all their comments here. Hopefully, the next time I post something on the board, it will be pics of my finished bathroom!!


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Date/Time11/19/2012 at 11:25:46 PM

Hello Brian, you wrote: ..."and was quoted $35k for a contractor to do this for me..." I assume this price was intended for the total bathroom remoddel inclusiv plumbing, tile-work, carpentry, electician and and and...inclusive all materials. But still sounds pretty high to me.

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Brian in Calgary
Date/Time11/21/2012 at 8:32:18 AM


Consider that I live in Calgary. Overpriced everything here, especially contractors. And that's even if you can find a reliable, trustworthy one.

Yes, $35k included everything.

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Date/Time11/23/2012 at 2:56:22 AM

Hello Brian,

I think I should move to Calgary. - I am reliable and trustworthy so I could demand even more money lets say $40k or even $45k. lol

Here in Vancouver are the prices maybe not that high, however it is the same pain for customers to find a reliable and trustworthy contractor.

I wish you good luck with your project.



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