Holes in Wood Studs 2

[carnahanad]

Hello,

I have a 2x6 load bearing wood stud wall that the contractor wants to put conduits through (1.25" - 1.5"). Most of the studs are actually under windows so I have quite a few full height triple king studs. I'm wondering what the max allowable hole through the load bearing studs is. I've read that in a single stud the max whole size is 20% the actual breadth and 60% if it's a double stud, however I'm not sure how realiable the source was. NDS only covers notches (as far as I can tell). Does anyone have suggestions regarding holes?

Thanks,
Alex

 

[Lion06]

I would just make sure the net section is still adequate.

 

[TenPenny]

One quick resource I found said max dia hole in a 2x6 stud on a bearing wall is 2.125" dia, min 1.6875 distance from the edges of the stud (ie, hole centered in stud).

http://www.ci.chula-vista.ca.us/Cit..._4592.pdf#search='max hole size and wood stud

 

[woodman88]

The 60% is for studs only that you can double to increase the size of the allowable hole. It does not apply to posts or columns. Please note that this is only noted for conventional light frame construction. This is also noted in the IBC light-frame construction section. For a wall you have designed you will have to come up with your own allowables. I have allowed larger holes at low stressed walls. See the attached for the light-framed allowables.

Garth Dreger PE
AZ Phoenix area

 

[asixth]

Thanks woodman,

that looks like a very valuable resource. It might be worthwhile putting a note in your standard notes or specifications regarding the maximum bored hole size and location for particular studs.

 

[woodman88]

Unfortunately, contractors and building inspectors will do and allow the light-frame maximums. So if you design a wall you do not feel will work per these maximums it is best to note them clearly on the plans, with their limitations. I have gone down to 6”o.c. (or double studs at 12” o.c.) #1 DF-L studs where required. Also have required 2x6 studs at the first floors.

Garth Dreger PE
AZ Phoenix area

 

[carnahanad]

Thanks for all the suggestions! I'm going to keep that pdf as a handy rule of thumb.

I did find the section in the IBC and discussed with some of my fellow engineers in house. To us, it seems that the guidelines for notching and boring would only be for a single stud or a small percent of studs in a long wall. We think that these notes in IBC are relying on the redundency of the wall to shed the load around the "weak" studs. However, if someone decided to bore through every stud in a wall, there could be major issues due to the complete compromise in strength of the wall. It seems like IBC could be more specific or have more information on this topic.

Thanks again for the help!