View Full Version : Eng. I joist

Randy Davidson
11-06-2006, 1:23 PM
I used a I beam floor joist system on my new home and am very happy at the sturdiness of this floor. I am to the point of running plumbing and everything seems to be no problem with one exception. I have a toilet that is on an outside wall and would'nt you know it, the flange will be located directly over a I-joist. Can this be notched to allow for the flange then use a 22.5 to direct it away from the rest of the joist? My only other option that I see is furring out the wall and reset the location of the flange. Not really what I want to do as it will decrease an already small toilet room. I am hoping someone has more experience with this floor system that I have had. I researched the manufacture web sites and found no info. I do have a call into my lumber supplier that setup the plan.

Lee Schierer
11-06-2006, 1:34 PM
On any supporting joist if you have to put a hole through it you want to do it near the middle of the I from top to bottom. Notching the top or the bottom will reduce the strength by a significant factor.

I would look for another way other than notching the top member or webbing of the joist.

One option would be to use a low clearance toilet. I know they make them for use in tight quarters.

Mitchell Andrus
11-06-2006, 1:49 PM
There are toilets that mount to the wall and flsh out the back.

You could also place the toilet on a raised box. This would mean stepping up to get on it and it wouldn't be handicap ready.


jeremy levine
11-06-2006, 1:54 PM
Some makes say NEVER notch the I-joist flange , so I would error on the side of safety.

Rob Russell
11-06-2006, 2:16 PM
You may be able to sheath the I-joist in plywood. The point is that you need to be able to transfer the load around the toilet flange.

I'd call the joist manufacturer and ask them what they recommendation is. Tell them that relocating the thundermug really isn't an acceptable option and what has to be done with the joist to maintain the structural integrity.

Brett Baldwin
11-06-2006, 2:25 PM
I seem to remember a similar situation in a DIY show I saw. They brought in a piece that relocated the output from the toilet several inches forward by putting in two bends in the piece. It takes the place of your wax ring. I'd ask a plumbing supply place in your area about it. I definitely would not cut your I-joist.

Another option would be to put another joist in to make up for the lost strength in the original. HTH

Dennis Peacock
11-06-2006, 3:36 PM

I'd have to agree with Lee...cutting the top of the I-Joist would greatly reduce the overall support structure. I'd prefer to move the toilet a little further out to avoid cutting the joist. But, check around and gather all your options before you decide.

Phil Thien
11-06-2006, 5:24 PM
Go with a wall-mount. Sure, they are more expensive. But they are a dream when it comes to cleaning, too.

Jim Becker
11-06-2006, 5:57 PM
Nope...cannot cut into the top of the I-joist. You can sometimes make rather "large" perforations in the web...how big depends upon "where" in the span and some other things, but touching the top and bottom of the I-Joist is a no-no. Outside of moving the potty farter out from the wall, a different style of toilet is probably your only choice.

11-06-2006, 6:06 PM
While 12" rough in is standard, most mfrs. make a couple of models in 10" and 14" as well. Don't know if that will help, but the cans in my old house were all 10". They only cost about twice what a standard 12" costs, so you'll still be hurting the first couple times you sit on it.

Robert Mickley
11-06-2006, 6:11 PM
Whats the possibiltity of putting a support just in from the end of the beam? From the basemnt floor up to the beam such as cemnt blocks or a steel post. That way the end of the beam isn't suporting much and notching it shoulnd be an issue than. Of course your going to have an intrusion into the basement space then.

Like so, black being the existing basement wall, red being the beam and blue being the added post