Joist Replacement

Users who are viewing this thread

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
Gutted 5x11 bath on the 1st floor of a ranch house. Need to replace a cut-up joist next to the closet bend, which runs under rear of shower. Here is my plan:

-Leave damaged joist, it is attached to plywood (in good condition), and no apparent sagging. The damaged joist was installed 40 years ago.
-Install new 2x10 adjacent to damaged joist.
-To keep 16 o.c. and to reduce deflection, install new 2x8 joist in next joist bay.

Is a 2x8 sufficient or just go ahead with another 2x10?
 

Sarg

Enjoy Learning
Messages
227
Reaction score
51
Points
28
Location
Upstate New York
Very difficult to imagine what you're working with without pictures. It sounds like you're assuring the floor will be super solid and won't "move". When you state "adjacent" does that mean laminating the damaged joist with the new 2 x 10 ? You don't mention the spans involved .... usage of joist hangers ..... room or clearance constraints with a 2x10 ?
 

DIYorBust

Active Member
Messages
745
Reaction score
94
Points
28
Location
Long Island, New York
Agree that we can't tell much without a picture. But it may make sense to use a header to support your 2x8 depending on how much of the original joist is left.
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
Very difficult to imagine what you're working with without pictures. It sounds like you're assuring the floor will be super solid and won't "move". When you state "adjacent" does that mean laminating the damaged joist with the new 2 x 10 ? You don't mention the spans involved .... usage of joist hangers ..... room or clearance constraints with a 2x10 ?
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
I'm new to the TLove Forum, 73 yrs old, and a long time DIYer, but don't want to do something stupid. New 2x10 cannot be sistered because closet bend protrudes 1" through damaged joist. Could sister if spacers are allowable between damaged and new joists.
Span is 11'9", in
crawlspace with 30" high work space. Notch is approx 5"x6" on 2x10, 37" from end of joist. I could box out from above or below, but not sure if the box out would be too far from the girder. Damaged joist is under toilet and proposed shower. If location of box is okay, I could add joist bay blocks to help with deflection. Another choice is to put 2 footings and install 48"-64" beam under 3 or 4 joists. Soil is hard clay.
Thanks for listening.
 

Attachments

  • 20201112_154821.jpg
    20201112_154821.jpg
    80.7 KB · Views: 174

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
Yes, I would use joist hangars.
Digging and installing 2 piers, posts and a beam would be easiest for me.
Less cutting, just grunt work, which is my specialty.
Once again, thank you for listening.
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
Your toilet drain is using a san-tee on its back for drainage, which is not proper, it should be a combo. Which you don't appear to have enough height for vertically, so some rearrangement of the drain pipes is in order.

Would it be possible to move the closet flange an inch or two so that a new 2x10 can be sistered to the notched joist without interfering with the sister? [E.g. use a 14" rough in toilet instead of a 12" rough in toilet, if I'm guessing correctly on the layout.] If so, then your toilet drain could just drop vertically to a 90 to be in plane with the lower horizontal drain, and then join that drain with a wye or combo.

If not, I guess sistering a 2x8 alongside the notched 2x10 (you indicated there was room for that) primarily as a spacer, and then sistering a 2x10 to that would be simplest. Your toilet drain could stay as is, except the 90 and san-tee could be replaced with a 45 and a combo rolled 45 degrees.

Cheers, Wayne
 

Sarg

Enjoy Learning
Messages
227
Reaction score
51
Points
28
Location
Upstate New York
Yes, I would use joist hangars.
Digging and installing 2 piers, posts and a beam would be easiest for me.
Less cutting, just grunt work, which is my specialty.
Once again, thank you for listening.
Jeff .... You have not mentioned what your concerns are regarding the floor structure .... Do you have a noted weakness or deflection & a bounce in the floor. Does it move OR are you seeking "peace of mind" because you can see it is not been properly done.
If it is preventing future issues because it just bothers the hell out of you it was not done properly ......... and I truly know what that is like ....... I would choose the pier reinforcement you describe.
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
Thank you Wayne.
Sistering 2x10 spacers along the damaged joist and around notched area, then sistering another 2x10 to 2x10 spacer would be best for me.
What is your opinion on putting a post and beam under 3 joists, on each side of notched area? Leave notched joist in place.
That's more in my area of skills.
Once again, thank you. This forum is terrific.
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
Assuming you fix the plumbing in a way that does not further obstruct the joist bays, but also does not move the closet flange, the carpentry options that come to mind:

- As you mention, turn the notched joist into a triple joist, with the middle layer just being spacers so the second new ply clears the toilet flange. [Personally, I'd rather move the toilet flange and use a single sister.]

- Just head off the notched joists on both sides of the toilet flange, as it's only one joist. You'd cut the notched joist plumb a few inches back from toilet on either side, and install an ~30" joist header perpendicular to the common joists, supported at the ends by the neighboring joists. The joist header on each side would carry the cut ends of your currently notched joist.

- Add a footing under the notch, with a 4x4 post going up to a horizontal length of 4x4 that extends say 3" past the notch on each end. [I'm not a big fan of this solution, as in the long run if there's any relative movement of your new footing versus the perimeter foundation, you'll have a disparity in support.]

- How wide is the notch, and how tall is the clearance between the bottom of the joists and the top of the lower horizontal drain? Say both are 4". Then you could do a "dropped header", namely a flat-wise 4x6 ~36" long that goes under the notch and gets secured to the bottom of the two adjoining joists with, say, 8" long timber screws.

Note that if there's any sag at all to the notched joist, several of these options would require temporarily jacking it back into plane.

Cheers, Wayne
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
Note: local builder suggested just sister 2x4's, where there is still 3 1/2" of wood remaining and stagger screw every 16". What's your opinion of this option?

Saw your last rely:
Notch is 6" T x 5" W.

I like the heading off option, looks more professional and wouldn't be affected by the possibility of foundation movement.
Would this be stronger than any post and beam set up, even though, the notch is 3 feet in from end of 11'9" span?

I'm in the boonies of NC, where things are pretty relaxed.
 

Attachments

  • 1605284043314927955954294058785.jpg
    1605284043314927955954294058785.jpg
    51.7 KB · Views: 160

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
A 2x10 is 7 times as strong and 18 times as stiff as a 2x10. So a double 2x4 doesn't come close, sistering with 2x4 is not adequate (but better than nothing).

Go with the box-out solution (heading off the cut joist). Looks like you have a continuous foundation wall under the "end joist" so your headers will be supported at one end. Overkill would be to sister the joist at the other end of the headers, but it is not at all needed for a single joist. [Would be required for heading off 3 joists, not sure about 2.]

Post and beam would be fine, it's just not so elegant and is more work over all.

But first fix your drain plumbing.

Cheers, Wayne
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
A 2x10 is 7 times as strong and 18 times as stiff as a 2x10. So a double 2x4 doesn't come close, sistering with 2x4 is not adequate (but better than nothing).

Go with the box-out solution (heading off the cut joist). Looks like you have a continuous foundation wall under the "end joist" so your headers will be supported at one end. Overkill would be to sister the joist at the other end of the headers, but it is not at all needed for a single joist. [Would be required for heading off 3 joists, not sure about 2.]

Post and beam would be fine, it's just not so elegant and is more work over all.

But first fix your drain plumbing.

Cheers, Wayne
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC
Would you double up the headers on each end?
Not necessary to double up the trimmers?

I'll quit bugging you. Thank you very much for your time and expertise.
 

Jeff Knecht

Member
Messages
135
Reaction score
2
Points
18
Location
West End, NC

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
Sure. R502.10 may contradict what I had to say about doubling the trimmer, so double check.

Cheers, Wayne
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks