Notched Joists - help

[jonrichard1]

Instead of drilling holes into our ceiling joists (putting in a bathroom/closet in the attic) my plumber actually NOTCHED out holes from the top of several joists!

In order to resupport these beams, can I just add on sister joists?

 

[dik]

Ain't ya ev'r herd of compressed air <G>...

Depending on the amount of space you have over the you may be able to sister a 2x something between the pipe. I've recently used a small angle secured and dapped into the joist in conjunction with 'glulam rivets'. Notch, hopefully isn't near the support...

Also some codes limit the maximum depth of a notch.

 

[SteveBausch]

Did your building inspector flag the work?

Is it causing a noticeable weakness?

Keep in mind the flooring can be a reinforcement, if done correctly. If the area is to be sheathed with plywood, you might consider glueing it down, and using a closely-spaced nailing pattern. You might also consider screws instead of nails.

 

[SteveBausch]

Actually, notching the top is the correct way to do it.

Here are typical code guidelines for notching:

Never in the center third of the span.
Only in the outer third of the span.
No more than 1/6 depth of joist.

Holes need to be 2&quot; from either edge of joist, the diameter no more than 1/3 depth of joist.

Pg 111,Residental Framing, William P. Spence 1993
Book availiable at 'big box' home improvement stores.

 

[wahmit]

Whether or not you have a problem depends on the joist loading and the notch size, shape and location. Assuming a 'normal' floor arrangement then the guidance given by SteveBausch is fine. If not then;
If it is a 'normal' floor arrangement and the notches are in the middle third but less than 1/4 of the joist depth then doubling up with joist of the same width and grade as the existing will be satisfactory provided the depth is greater than 3/4 of the existing.
Otherwise get professional advice.

Just for information notches are generally preferred to holes in beams near supports, the maximum shear stress occurs at the middle of the joist.

 

[rlflower]

To add to all the above suggestions: Take a close look at how the contractor over-cut the notches (allow me to presume he has done so). The depth of the notch should be considered equal to the depth of the cut.

-Richard L. Flower, P. E.