Notch in floor Joist

[gautamraj]

I have a project in which the contractor notched several existing floor joists to install new pipes. The floor joists consists of full 2x10 at 16” on center. The joist spans are 10’ and 14’ with a mid support. The joists are continuous over the mid support. The notch is within the mid 1/3 span in the 10 foot span. The depth of the notch varies but is less than 1.5”.


Because of the electrical wires already installed, the contractor does not want to sister a new 2x8 (2x8 is adequate for bending and deflection). I am thinking of jacking up the joist to counter the dead load deflection and installing a Simpson 12 gage metal strap across the notch at the bottom face of the joist.



Your comments and insight would be appreciated.



Gautam

 

[jhoulette]

I did a quick run using 2x8 @ 16"o.c.
loading of 40psf LL, 15psf DL
Hem fir #2

To me it works, it fails in negative moment at the center support when fully loaded, but that's not your issue. Your issue is positive moment and deflection of the 10ft span.
It works assuming only 7 1/4" depth of joists.

If the strap won't interfere with the ceiling attachment, go for it. I've also used an OSB ceiling before the gyp is attached depending on the room size. But I wouldn't go for it on this one.
Slap the contractors hand and move on.



Jim Houlette PE
Web:

http://www.evstudio.com

Online Magazine:

http://www.evstudio.com/blog

 

[msquared48]

Straps have worked fine for me in the past, in fact a recent problem of the same nature - damn plumbers!

Do the straps - it's the cheapest and easiest. Just make sure the strap is designed to develop the tention force the joist sees.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[woodman88]

Basically (IMHO) a notch in the center third of a simple span joist is like ripping the member. Per the lumber grading rules, it would have to be regraded. One way I have addressed this is to limit the size of knots and holes (as the size of holes and knots are one of the basic factors that controls the grading of the members) within 18” of the notch. Such as for 2x10's with a maximum 1.5” depth x 3” long notch, knots and holes no greater than; select structural – 1”, #1 – 1.25”, #2 – 1.75”. I would still use a strap along the bottom of the joist, minimum of 3' length.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.