Kitchen renovation--NEED HELP w. joist!!

[gacuri]

Can someone please help me with this question? My kitchen renovation may need to have a drain vent pipe relocated through few existing structural wood joists. Is that safe to do? The joists are 2x10 and the pipe is 1-1/2" the hole on the joist would be 2". Thanks!!!

 

[Aguanga]

Building a house right now, but I'm using TJI's which provide A LOT more flexibility with holes. In the past, i had always been told to use the one-third rule on conventional 2x joists. It meant not to drill within one-third of the ends of the joist lengthwise and not to drill in the top or bottom third of the joist.

Hopefully someone else can confirm or reject this...

 

[Timber]

Post a picture of the area lets see what your options are

 

[bobodu]

You'd be fine.

 

[davitk]

With solid lumber, the holes must be no closer than 2" from the top or bottom of the joist, and a maximum of 1/3 the joist depth (2x10 = 3 1/8" hole). Also, no notching in the middle 1/3 of the joist span.

KEEP AN EYE ON THOSE DARN PLUMBERS!!

 

[Charlesaf3]

With solid lumber, the holes must be no closer than 2" from the top or bottom of the joist, and a maximum of 1/3 the joist depth (2x10 = 3 1/8" hole). Also, no notching in the middle 1/3 of the joist span.

KEEP AN EYE ON THOSE DARN PLUMBERS!!

You've got your answer here.

Pay special attention to the stuff in all caps. I like to ask my plumber what the difference between a plumber and termites is - answer, termites tend to do much less structural damage.

 

[CurlyDave]

The answer is more complex than anything you have so far.

What is the span of the joist?

If you are near the maximum span for the joist, davitk's answer is good. If the span is less than maximum, you have considerably more leeway in the holes, notches, etc. that you can cut.

 

[Charlesaf3]

true, but without getting into engineering tables, davitks answer is a safe one.

 

[Whitey]

Without re-inventing the wheel I would say that if you are concerned about the hole size or it's location.....here is what I would do. You can add structural full depth bridging to both sides of the opening tying the punched joist to the joists at either side or.....you can make a cleat out of 3/4" plywood that spans 32" inches in either direction of the hole centered on both sides of the joist. Glue / screw it to reinforce the area then drill your hole. The plywood will help reinforce the area that is to be punched. Be sure to make the cleats large enough or they will be useless.

I recently added cleats to both sides of a purlin / hanging truss affair in my 100 year old shop so the ceiling would handle the weight of type X drywall, insulation and a USG ceiling grid. Worked great.

JD 770 / 70 FEL / 7 BH - 425 AWS / 54" MMM / 54" FMP

 

[Cord]

With solid lumber, the holes must be no closer than 2" from the top or bottom of the joist, and a maximum of 1/3 the joist depth (2x10 = 3 1/8" hole). Also, no notching in the middle 1/3 of the joist span.

This is the text book perfect response.

 

[Brad_Blazer]

Link to NC plumbing code on this topic:
http://ecodes.iccsafe.org/nxt/gateway.dll/Plumbing/chapter01246/section%20head01247/subsection01248.htm?fn=main-nf.htm$f=templates$3.0

"Notches on the ends of joists shall not exceed one fourth the joist depth. Holes bored in joists shall not be within 2 inches (51 mm) of the top or bottom of the joist, and the diameter of any such hole shall not exceed one third the depth of the joist. Notches in the top or bottom of joists shall not exceed one sixth the depth and shall not be located in the middle third of the span."

Davitk's rule agrees but holes and notches are not the same thing i.e. properly placed holes in the center 1/3 are permissable, notches are not. The principles in play are that bending stress is highest at the center of a span and that the top and bottom fibers of the joist carry the majority of the stress.

Check the code in your state.

 

[davitk]

Link to NC plumbing code on this topic:
http://ecodes.iccsafe.org/nxt/gateway.dll/Plumbing/chapter01246/section%20head01247/subsection01248.htm?fn=main-nf.htm$f=templates$3.0

"Notches on the ends of joists shall not exceed one fourth the joist depth. Holes bored in joists shall not be within 2 inches (51 mm) of the top or bottom of the joist, and the diameter of any such hole shall not exceed one third the depth of the joist. Notches in the top or bottom of joists shall not exceed one sixth the depth and shall not be located in the middle third of the span."

Davitk's rule agrees but holes and notches are not the same thing i.e. properly placed holes in the center 1/3 are permissable, notches are not. The principles in play are that bending stress is highest at the center of a span and that the top and bottom fibers of the joist carry the majority of the stress.

Check the code in your state.

Good post. And may I add, which may or may not help to clarify, that one of the reasons notching is so potentially dangerous in a joist is that wood tends to split along the grain where it is nicked (i.e. a saw kerf), while a round hole is OK midspan (think knothole)

To further muddy the waters, when notching joists or stair stringers, some carpenters advocate drilling a whole at the inside corner, then cutting the notch

 

[Danno1]

To further muddy the waters, when notching joists or stair stringers, some carpenters advocate drilling a whole at the inside corner, then cutting the notch

Actually, that's not necessary as the corner is in compression in that situation. The purpose of the round hole is to relieve stress when the corner is in tension.

.

 

[davitk]

Actually, that's not necessary as the corner is in compression in that situation. The purpose of the round hole is to relieve stress when the corner is in tension.

.

Top or bottom?

 

[Danno1]

Top or bottom?

In a house, the joists/stringers are all loaded fr the top. That puts the top in compression and the bottom in tension. Since stair stringers are notched on the topside, there's no need to drill a round hole at the corner of the tread/riser. In a machine the stresses could come fr various directions. The carpenters are confusing this situation w the stair stringer situation. I could explain better w a picture but don't have a convenient way to do that right this minute.

Do a Google for stress concentration factor, notch strength, notch sensitivity, or stress riser.

.

 

[davitk]

In a house, the joists/stringers are all loaded fr the top. That puts the top in compression and the bottom in tension.

Stringers aside, plumbers do not know top from bottom when it comes to boring and notching wood joists; tops and bottoms get equal mistreatment. Their job is to make the pipes pitch downhill, the carpenter's job is to fix it. More often than not the sheetrock covers the mess and the project is called done.

 

[TomSr]

Since you are talking about a vent I assume you mean a ceiling Joist. You might consider going up and over the top of joist. When I built my house I ran a vent line using 4" pvc from vent to vent and put one pipe through the roof. Just tide all vents together in the attic.

 

[KennethBrown]

Something I never considered because I was reading over it also- You said VENT. WHat about an air admittance valve aka Stoddard?