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View Full Version : Holes near joist end - how close?



Michael Thomas
09-17-2006, 08:20 AM
In a conventional (dimensional) lumber floor joist is there any limitation how close to the end of a joist an otherwise allowable hole can be placed?

The 2003 IRC says:

R502.8.1 Sawn lumber. Notches in solid lumber joists, rafters and beams shall not exceed one-sixth of the depth of the member, shall not be longer than one-third of the depth of the member and shall not be located in the middle one-third of the span. Notches at the ends of the member shall not exceed one-fourth the depth of the member. The tension side of members 4 inches (102 mm) or greater in nominal thickness shall not be notched except at the ends of the members. The diameter of holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches (51 mm) to the top or bottom of the member, or to any other hole located in the member. Where the member is also notched, the hole shall not be closer than 2 inches (51 mm) to the notch.

It would seem to me that you would not (for example ) want to place an otherwise allowed hole closer than to the end of a joist than to another hole, but the code does not seem to directly address this question.

The specific situation is a kitchen ceiling where it's desired to to move a 2” drain currently running along a wall surface into the ceiling above to eliminate an existng soffit, unless the drain is relocated it will be sitting as close to the joist end as possible and still avoid the joist hangers.

The first question is: per “code” can it be this close, or would it have to be relocated further out from the joist end, and if so, how far?

The second question is: as at least four adjacent 2x10” joists will be drilled, is there a consensus here as to “industry best practice” for the distance from the joist end?

Thanks,

Michael Thomas
Paragon Home Inspecton, LLC
Evanston, IL
mdt@paragoninspects.com
847-721-0776

dgbldr
09-17-2006, 09:19 PM
From the viewpoint of the joist as loadbearing beam of sorts, the further out the better. That's where the beam loads are the smallest.

On the other hand, if the end of the joist has another load on it, such as a vertical compression load if it's between 1st and 2nd floor wall framing, then common sense would dictate that you don't want a 2+" hole in that load path.

In other words, not directly above the kitchen wall top plate.

Gbrogden
09-18-2006, 12:08 AM
I'm not sure that it matters how close to the end of the joist the hole is. The important thing is that the hole can not be any further away from the end than 1/3 the total span of the joist. The middle 1/3 of the span must be clear.


I'll ask the plumber on our job tomorrow and see what he has to say.

houseboy
09-18-2006, 06:03 AM
I think you have that backward Gbrogden. Shear is generally higher near the ends of the joists and so we would prefer to limit the holes in that area. Since shear stresses are lower out in the middle part of the span, it is often suitable to place holes there (from the standpoint of joist stresses. Of course there are limits to the hole placement (such as away from the top and bottom of the joist).

Gbrogden
09-18-2006, 06:28 PM
The plumbers weren't in today, but I did thumb thru one of the condensed code check books at Lowe's today.

I was almost right. It's notches that aren't allowed in the middle 1/3 of the span. I thought it was both. That's what I get for being a trim carp. According to the book, holes are ok anywhere along the span on dimensional lumber. However, it did specify some min dimensions for hole placement in TJI's.

George Roberts
09-18-2006, 08:41 PM
I don't run across these problems but ...

I think I would treat the joist lke a stud and not allow a hole greater than 40% of the wall joists.