ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
UL 508A SPACING
by ale348 - 03/29/24 01:09 AM
Increasing demand factors in residential
by tortuga - 03/28/24 05:57 PM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (ale348), 302 guests, and 14 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#153613 10/22/03 07:58 PM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline OP
Moderator
What are we allowed to do to a truss, as far as drilling, cutting, notching, altering, etc...

[Linked Image]


Ryan Jackson,
Salt Lake City
Stay up to Code with the Latest NEC:


>> 2023 NEC & Related Reference & Exam Prep
2023 NEC & Related Reference & Study Guides

Pass Your Exam the FIRST TIME with the Latest NEC & Exam Prep

>> 2020 NEC & Related Reference & Study Guides
 

#153614 10/22/03 09:46 PM
Joined: Nov 2002
Posts: 558
G
Member
Ryan, I looked at some of the paperwork that came with some roof trusses the other day. It basically said no drilling, notching,notching,chopping or hacking.

If you must do one of the above,it says to consult a structural engineer.

Russell

#153615 10/23/03 12:41 AM
Joined: Jul 2003
Posts: 394
B
Member
Pretty much, any alteration to an engineered truss requires approval of the manufacturer or a competent authority (licensed professional engineer). No holes, notches, cut, etc. without written permission. Engineered beams - LVL and the like - are the same story. They usually come with installation instructions showing allowable holes.

#153616 10/23/03 05:06 AM
Joined: Jan 2003
Posts: 4,391
I
Moderator
I agree with the others.

Nothing is to be done to modify the truss in any way without an engineer signing off on it.

Once an engineer is involved you can do what ever he/she designs and signs for.

I mostly work with steel truss and we are not allowed to support off of the bottom cord on most jobs, this includes I beams too.

On these jobs the ceiling contractor must tie off to the top chord of the truss.

And if I ever took a sawzal to a steel truss the GC would have me paying for repair replacement. [Linked Image]

[This message has been edited by iwire (edited 10-23-2003).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#153617 10/23/03 04:38 PM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
In most single family homes I've worked in they've had 2 x 6 (or better) joists for the ceiling/attic floor @ 16" on center.

It's common for the Attic to be used for storage around here too. What kind of an Attic storage load would these Trusses support? Is that figured in the design of these things?

Bill


Bill
#153618 10/23/03 04:42 PM
Joined: Feb 2003
Posts: 67
P
Member
all excellent answers [Linked Image].it is amazing what forms of truss butchery an inspector sees during framing inspections.one person had to remove the roof and start over.they were not happy campers. [Linked Image]sometimes the engineers cannot design a fix as was the case.think before you butcher!

#153619 10/23/03 04:59 PM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member


Bill
#153620 10/24/03 09:42 PM
Joined: Aug 2003
Posts: 123
P
Member
I don't remember drilling holes in trusses.

It was never allowed.

Joists were a different story.
One carpenter I talked to, said joist manufacturers had guidelines.
It was a simple math thing. Size of hole, number and spacing of holes, width of joist, distance of holes from center or end, span of joist.........etc.

It sounds confusing, but the math is like sizing conductors for pipe fill.

When we rarely had to go through a truss, we told the carpenter the situation, and he either 'boxed' out a section or showed us a better route.

Joists are one story, but I feel one should never, ever, drill a truss!

#153621 10/25/03 12:00 AM
Joined: Jun 2003
Posts: 681
P
Member
Unless designed otherwise, the truss frame construction supporting the floor of an attic are not designed to carry much of a load. I do not have my book here, but I will try to read it at work and let you know.


When running wire in an unfinished attic, lets not forget about 320.23, especially since drilling is not an option!
Pierre

[This message has been edited by PCBelarge (edited 10-25-2003).]


Pierre Belarge
#153622 10/25/03 12:22 AM
Joined: Nov 2002
Posts: 558
G
Member
Pierre,since you brought up 320.23,I am always scrambling to comply with this one.
A lot of times the framers will put an attic acess in after I'm long gone. And it always seems to wind up where I presume to be the least likely place,and of course right next to several wire runs that would have been way out of the way otherwise.


Russell

Page 1 of 2 1 2

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5