Replacing floor joists

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Dan O.

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I'm replacing some rotted 2" x 6" floor joist under my 5' x 8' bathroom, attached picture shows the situation I'm looking at.

So, I can notch the ends of the new joists and they'll be level and match the ends of the existing joists. Question I have about this is can I notch the joists to that extent w/o (seriously) compromising their strength? The span between foundation wall and the beam is 80".

Alternately, I can forget about notching the new joists but will have to do something about the resulting valley. I can think of something that will give me a flat floor but not both flat and level. My intent is to install tile flooring over Ditra so flat and level would be nice.

All ideas welcome.
 

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Jadnashua

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New joists tend to be smaller than the old stuff. When you notch a joist, you effectively make the whole thing the resulting depth of the notched section, not the larger dimension.

To make the new subflooring both level and flat, you can add something like a 2x4 bonded to the side of the joists that is level and in plane, and attach your new subflooring to it. Use construction glue and deck screws to laminate those to the side of the joists
 

Reach4

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So, I can notch the ends of the new joists and they'll be level and match the ends of the existing joists. Question I have about this is can I notch the joists to that extent w/o (seriously) compromising their strength? The span between foundation wall and the beam is 80".
Notching at the ends is not like reducing the size of the whole board, since the stresses are greater in the middle of the span.
 

Jadnashua

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Ever seen a joist split? Guess where it starts...at the notch. To obtain the full strength, do not notch it. Now, if you add a joist hanger, you'll be supporting full depth unless the notch is huge.
 

Dana

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A half inch notch at the end of a 2x6 that only has to span 6'8" isn't a big deal at all.

The eternally worried could shim up the inch or so between the top of the concrete and the bottom of the full-dimension part of the joist.
 

Dan O.

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To make the new subflooring both level and flat, you can add something like a 2x4 bonded to the side of the joists that is level and in plane, and attach your new subflooring to it. Use construction glue and deck screws to laminate those to the side of the joists

I wish the solution were this simple but the high point is at the foundation wall, a level line extending from that point by whatever means would result in the bathroom subfloor being 1/2" higher where it meets the hallway (right side of pic).

The "flat only" floor solution I mentioned would extend a line from the existing joists at the hallway to a point 5 1/2" above the foundation wall (shims, sistered joist, whatever); flat but would not be level.

The sistering approach works fine for dealing with low spots but in my case 95% of the house is the low spot.:(
 

Dan O.

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A half inch notch at the end of a 2x6 that only has to span 6'8" isn't a big deal at all.

The notch I'm proposing would remove a 1/2" x 4" rectangle from the bottom left end of each new joist, I'd have to look it up but I believe that goes beyond what is usually permissible.

The eternally worried could shim up the inch or so between the top of the concrete and the bottom of the full-dimension part of the joist.

Supporting the bottom of each new joist where they're still a full 5 1/2" deep would certainly make me feel better, would that actually be effective? Can I do something like bolt a 2" x 4" on the foundation wall under the joists?

I know it seems like I'm being awfully anal about this considering it didn't seem to bother the original builder much but these were the same guys that thought glued on plastic tiles made a great tub surround.
 

Dana

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As long as the ledger strip is bolted to the foundation wall in a manner that meets local seismic code requirements, it's a generally accepted solution. (
(As I understand it codes will vary on some of these details within CA based on location.)

The original builder sounds like a real gem...
 

Patrick Dunn

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The notch I'm proposing would remove a 1/2" x 4" rectangle from the bottom left end of each new joist, I'd have to look it up but I believe that goes beyond what is usually permissible.



Supporting the bottom of each new joist where they're still a full 5 1/2" deep would certainly make me feel better, would that actually be effective? Can I do something like bolt a 2" x 4" on the foundation wall under the joists?

I know it seems like I'm being awfully anal about this considering it didn't seem to bother the original builder much but these were the same guys that thought glued on plastic tiles made a great tub surround.
I had an issue with bouncing floors and searched forever. I did find this company called structure Lock that uses metal Ijoists.

Try them out structure lock.com
 
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