Plumbers Drilled through Joists...Is this Acceptable?

ScipioAfricanus · Dec 8, 2015

O.K. let's make some assumptions. That these are indeed 2 x 8 double joists as we can see. Double 2 x 8s are effectively single 2 x 10s for practical purposes. 16" centers assuming DF#2 grade lumber can span 15'-5" with a delta of L/360 @ 40 lbs. Live Load so we look good there.
A 3-1/2" hole in the left or right 1/3rd of a CJ is O.K. by most prescriptive codes but not in the center which it looks like these are not in the center 1/3rd. Groovy although there are two holes in one of the doubled joists.

It maybe good to go. Ask the SE.

Andy.

madmax718 · Dec 8, 2015

from the pic it looks like they are all doubled.

Tom M · Dec 8, 2015

Golden view said:
14' is a pretty long span for 2x8. I bet that's why they are doubled.

At the end of the day, I bet you are fine. The doubling does help, and a lot of the requirements are very conservative and consider the hole may have been drilled right next to a knot or some other weak spot in the joist. Doubling reduces the chance of this.

Good point on the deflecting span. A lot of designers consider that bathrooms carry extra weight and joists are going to be drilled thus the request for doubling those framing members. We dont know if the whole section of the floor plan is double because of the span.

Golden view · Dec 8, 2015

ScipioAfricanus said:
A 3-1/2" hole in the left or right 1/3rd of a CJ is O.K. by most prescriptive codes but not in the center which it looks like these are not in the center 1/3rd. Groovy although there are two holes in one of the doubled joists.

It maybe good to go. Ask the SE.

Andy.

You sure about this?

Calidecks · Dec 8, 2015

Joist depth divided by 3. A 2x8 divided by 3 is 2.5" that would be the max allowed by prescriptive code.

They may be doubles but there is no prescriptive code for doubles so without an engineer approval that hole can't be more than 2.5".

Calidecks · Dec 8, 2015

Code says no notches permitted in the centre third of joist but allows holes as long as it meets the D/3 rule and has at least 2" of material on the top and bottom of hole.

mrcharles · Dec 8, 2015

Golden view said:
14' is a pretty long span for 2x8. I bet that's why they are doubled.

At the end of the day, I bet you are fine. The doubling does help, and a lot of the requirements are very conservative and consider the hole may have been drilled right next to a knot or some other weak spot in the joist. Doubling reduces the chance of this.

I agree that the doubling was for the span and the Arch wasn't considering plumbing notches...

ScipioAfricanus · Dec 8, 2015

ScipioAfricanus said:
O.K. let's make some assumptions. That these are indeed 2 x 8 double joists as we can see. Double 2 x 8s are effectively single 2 x 10s for practical purposes. 16" centers assuming DF#2 grade lumber can span 15'-5" with a delta of L/360 @ 40 lbs. Live Load so we look good there.
A 3-1/2" hole in the left or right 1/3rd of a CJ is O.K. by most prescriptive codes but not in the center which it looks like these are not in the center 1/3rd. Groovy although there are two holes in one of the doubled joists.

It maybe good to go. Ask the SE.

Andy.

On thinking about his again a 3-1/2" hole even in a doubled up 2 x 8 would probably not fly.

Andy.

Tom M · Dec 8, 2015

I hope there is a follow up on this it would be nice to know

fjn · Dec 9, 2015

I can see easily why the spec. called for doubling joists. Old rule of thumb that can apply for spans up to 16' is as follows. Take span,divide by two and add 2" to joist. So,14' divided by 2 = 7 + 2 = 9. Since there are no 9" joist,you always round up for odd numbers like 3,5,7,etc.

Single joists should have been a min. of 2"x 10".

Tom M · Dec 9, 2015

The two joist in question are at least sharing the load of what I assume is a partition above.

I rarely see anyone take advantage of the code when it comes to end notching. If you had the foresight and space one could go to a bigger joist and notch up to down to keep in plane.

fjn · Dec 9, 2015

Here is an article from F.H.B. on 6 ways to stiffen a floor. Of course,if strengthening is needed,run this up the flag pole and see if the P.E. salutes.

http://m.finehomebuilding.com/PDF/021184090.pdf

cedarboarder · Dec 10, 2015

Is it micro lams or para lams that can be drilled out more than normal wood joists??
I always forget.

And thank you for not dry walling that.
Doubt it would pass inspection any ways...

Calidecks · Dec 10, 2015

cedarboarder said:
is it micro lams or para lams that can be drilled out more than most joists??
I always forget.

It is an engineers call. There is no prescriptive code for drilling beams.

Inner10 · Dec 10, 2015

Californiadecks said:
It is an engineers call. There is no prescriptive code for drilling beams.

The beam manufacturer lists the drilling allowances.

Leo G · Dec 10, 2015

So...was I right?

mrcharles · Dec 10, 2015

Inner10 said:
The beam manufacturer lists the drilling allowances.

For the beam itself, but they don't look at the complete building assembly top determine if the hole can be made or not.

cedarboarder · Dec 10, 2015

Californiadecks said:
It is an engineers call. There is no prescriptive code for drilling beams.

Yeah..... I just enjoy problem solving.

cedarboarder · Dec 10, 2015

Inner10 said:
The beam manufacturer lists the drilling allowances.

yes they do.
the best beam for this application is a LSL beam.

but like FJN said this should have been 2x10 they don't even make TGI in 8" do they? only see 9 1/4" to 16" in spec booklet.

cedarboarder · Dec 10, 2015

:whistling

Plumbers Drilled through Joists...Is this Acceptable?

ScipioAfricanus

madmax718

Tom M

Golden view

Calidecks

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Calidecks

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mrcharles

ScipioAfricanus

Tom M

fjn

Tom M

fjn

cedarboarder

Calidecks

Inner10

Leo G

mrcharles

cedarboarder

cedarboarder

cedarboarder

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