Holes in Wood Joists

[SteelPE]

I have a client who is wanting to drill a hole in his floor joist. I have some concerns about the hole that I need to back up with the code. The client wants to drill this hole 13" from the support of the joist. For some reason I can't seem to find the limitation as to how far from the support you are allowed to drill holes. The only thing I can find is where the code states that you can't drill a hole larger than D/3. Is there such a limit in the code?

 

[JAE]

I think the limit is inherent in the design check you'd do. With a reduced section you have reduced shear capacity and at some point closer to the support that might limit your hole size/location.

 

[woodman88]

IHMO
1) Neither the IRC or IBC has a end distance requirement for joist holes placement.
2) If you designed the joist (or the joist could be designed) per the Conventional Light-Frame Construction Section 2308 of the IBC or the IRC, then you can use the D/3 hole size.
3) If you are designing it under the NDS then the allowable hole size of D/3 is not stated any where that I can find. When I design under the NDS I use the WWPA limitations on hole sizes and spacing per grade and size of the 2x to 4x joists/beams, for the general placement of the holes. Where I know the location of the hole and whether there are no other holes/knotholes within one to twice the depth of the member to it. Then if the reduced section calculations work I will go up to the D/3 size for the hole.
4) At bearing ends the hole should be a minimum the depth of the member away from the inside face of the bearing. If not, I then to look it the hole more like a notch. And hope that the joist/beam has low enough shear to get it to work. It has been more of a problem with beams rather then joists.

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.

 

[msquared48]

Lacking further guidance, I would defer to the minimum guidelines for bolt placement of 4 to 7 times the diameter of the hole for edge and end distances.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[msquared48]

Truss Joist, in their "Beams, Headers and Columns" catalog using Microlams and Parallams, on page 36 of the May 2012 Catalog, has some pretty good guidelines for general hole placement in different situations.

You might be able to extrapolate this to other types of standard wood joists too, outside of TJI's and the like.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com