Joist in the way of new shower drain

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wvphysics

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I am replacing a shower in one of my bathrooms. It was old and dingy, and most of all it was not level (one corner pooled an inch or two of water). I am putting in a shower pan and tiling the walls of the shower. I am also redoing a very shoddy tile job on the rest of the floor that was put directly onto one layer of subfloor. After I cleaned up the subfloor I added a second layer of subfloor to support the tile. I layed down the shower pan and marked the drain hole. When I cut out the hole I found that the drain hole move just enough for a joist to be in the way. The edge of the joist is just about at the halfway mark. Using an offset drain doesn't quite clear the joist so now I am trying to figure out the most feasible option to get around the joist.

The two options I can see are notching and cutting the whole section of the joist out and putting in headers. Whichever option I choose I want to make sure I don't weaken the floor enough to disturb the tile floor. These are 2x10's so I believe I am allowed to notch down just over 1.5". I only need to clear about another 1/4" so I am thinking of using a 45 or 90 elbow and notching just enough to fit in the elbow. Does anyone have any thoughts on whether this level of notching would cause a problem, or would headering out be stronger and cause less deflection?
 

Dana

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The amount of deflection you'll experience depends on how far away from the joist supporting beams/walls that notch is. If it's 8' to the nearest support the deflection is going to be a lot more than if it's less than 2' away.
 

wvphysics

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Good point. The side of the shower is up against the exterior framing and the joists rest on the block wall foundation underneath so it's only about 20" away from the joist support.
 

Jadnashua

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IMHO, it's never a good idea to notch joists! There are rules for putting holes through them, but they include how close to the ends, and how big they are with regards to how much is left. A joist is sort of like a truss...the middle just keeps the outer edges in place, and for tension on the bottom and compression on the top, is what provides the deflection strength. Since you have additional bearing forces near the ends is why there are limits on how close to the ends you can cut. I would not want to cut a notch underneath a shower especially with the weight of the pan and tiled walls.

I'd probably put in headers so I had access, but you might be able to sister the joist you cut to help with the cut's loss of strength.

Is the room already tiled? Hopefully, you have access from below, otherwise, you'll be tearing up the new ply you added along with the original floor.
 

wvphysics

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I believe the guidelines for notching joists is 1/6th the depth of the joist, which is why I am considering it as an option. I have access from underneath. It's over the garage with unfinished drywall, I already have the section of drywall down under this section. If I were to header out it would go over a wall into the laundry room with a drop ceiling.
 

Jadnashua

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Yes, 1/6th is allowable, and there is a limitation on the length, as well. Personally, I'd try to avoid them.
 
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