Holes drilled in roof trusses

[hillbilly]

Will someone please define and/or post an image of a running board?

I don't have a photo but...A running board is a piece of lumber that is nailed (or screwed) to the bottom of the floor joists (at right angle). The NM is run with and stapled to the sides or bottom of this board. I usually use what ever (scrap) is laying around the construction site. No particular size, usually a 2x2 or a 2x4.
steve

 

[Smart $]

And how is this better than stapling to the bottom of joists, aside from providing the option to staple at intervals less than the spacing of joists? Generally, joists are spaced 16" O.C. here. The code is supported/secured at intervals not exceeding 54".

 

[infinity]

And how is this better than stapling to the bottom of joists, aside from providing the option to staple at intervals less than the spacing of joists? Generally, joists are spaced 16" O.C. here. The code is supported/secured at intervals not exceeding 54".

For one thing someone couldn't hang something on the NM cable if it's attached to a running board. I have seen AC cable run under the joists in laundry area of a basement with clothes hung on hangers from the cable.

 

[celtic]

Will someone please define and/or post an image of a running board?

A running board is simply a length of wood...there are no specific dimensions noted for these...typically, they will be the cheapest 1x3 available (to keep cost down) that will accomodate the number of cables stapled to them.

OK we need help.
Pictures? Anyone of a "2x4" truss

This is a 2x4 engineered truss system.
Notice the large metal ties that join the 2x4s to eachother.

 

[iwire]

And how is this better than stapling to the bottom of joists, aside from providing the option to staple at intervals less than the spacing of joists?

You must be trying to live up to your name.

I thought it was obvious that running boards offer some level of added protection against using the NM as a support?

 

[Smart $]

You must be trying to live up to your name.

I thought it was obvious that running boards offer some level of added protection against using the NM as a support?

Hehehe!

Actually, I've only worked concrete and steel structures for the past 15 years, and very little residential prior to that. I have never seen running boards used as a means of support for NM, always holes in joists or bottom stapling, and wanted to get a clearer picture in my head. "Some level of added protection" is correct, but clearly not to any great degree

 

[iwire]

I have never seen running boards used as a means of support for NM, always holes in joists or bottom stapling, and wanted to get a clearer picture in my head. "Some level of added protection" is correct, but clearly not to any great degree

Matter of opinion.

I would say between NM run exposed thorough holes in joists and NM run exposed on running boards I say the running boards add a lot of protection.

From none to some.

 

[Smart $]

Matter of opinion.

I would say between NM run exposed thorough holes in joists and NM run exposed on running boards I say the running boards add a lot of protection.

From none to some.

Yeh, none to some is an infinite improvement...

...but only if the NM is stapled at intervals not exceeding that of the joists. Stapling could be taken to the 54" limit and tensioning NM so tight as to prevent someone from getting a hangar around it is impossible.

 

[iwire]

...but only if the NM is stapled at intervals not exceeding that of the joists.

Again a matter of opinion.

It could be taken to 54" but I do not see that happening.

But like you I do not spend much time in wood structures.

Even as qualified persons, it is impossible for us to make our installations idiot proof, but if it saves one life, something as little as the color of a short piece of tape is worth it...!!!

Or some wood strapping.

 

[Smart $]

Touch?!

 

[Minuteman]

Bob, you have an awesome memory!

 

[celtic]

Did we scare the OP off?

 

[77401]

This is a 2x4 engineered truss system.
Notice the large metal ties that join the 2x4s to eachother.

LOL
I knew you'd have the picture! Your amazing with the images!
No way would anyone drill these! can't the board running down the center be used for running boards if its protected with a board nailed perpendicular?

 

[celtic]

LOL
I knew you'd have the picture! Your amazing with the images!

While I appreciate the applause , don't be too impressed

Just like no one knows the NEC from front to back verbatim (or maybe some of the cranial endowed do??), many of us just know WHAT to look for and WHERE to look.

Same concept applies to what I "have"...what I "have" is the ability to plug words into a search engine ...LOL.
Not much of a "skill" but hey, I've accepted my mediocrity and harnessed it's awsome power

 

[Minuteman]

Not much of a "skill" but hey, I've accepted my mediocrity and harnessed it's awsome power

My new motto!

 

[batch]

When we put a sign up. Say individual letters with neon. We have a lot of 1" electrical holes. When we drill these we often hit wooden or metal studs running vertical in the wall. The most common practices are to drill through the stud until you pass completely through it or to angle the hole to one side or the other.

What does the code say about these penetrations?

If allowed, is there some sort of protection required.

I have been told that you can not drill through any structural member. But, have also never seen a violation issued. Just warned against.

Like o hear your alls advise here.

 

[BarryO]

You can not ever drill or cut a truss.

Unless a piece of paper with a PE stamp on it says it's OK, and how to do it.

Common dimensional lumber usually has some "headroom" in certain places, and the building code take that into account; e.g., there's little shear in a horizontal beam in the middle third, so the codes let you drill holes in that region in floor joists. OTOH, they experience alot of compression on the top edge and tension on the bottom, so notches here are a no-no.

Each member in a truss is either in tension or compression, are typically designed to minimize material, and usually don't have much "headroom". You have to run the engineering analysis to determine if reducing the cross-section of an a particular member (drilling) is OK. The good news is that it's probably possible to design a repar procedure, given that the forces on each member are either simple tension or compression, and not something more complicated.

 

[Jim W in Tampa]

Unless a piece of paper with a PE stamp on it says it's OK, and how to do it.

Common dimensional lumber usually has some "headroom" in certain places, and the building code take that into account; e.g., there's little shear in a horizontal beam in the middle third, so the codes let you drill holes in that region in floor joists. OTOH, they experience alot of compression on the top edge and tension on the bottom, so notches here are a no-no.

Each member in a truss is either in tension or compression, are typically designed to minimize material, and usually don't have much "headroom". You have to run the engineering analysis to determine if reducing the cross-section of an a particular member (drilling) is OK. The good news is that it's probably possible to design a repar procedure, given that the forces on each member are either simple tension or compression, and not something more complicated.

The fix is glue and 4 feet of 2 x 4 on both sides and about 50 nails from a nail gun.That's the cheap part.The piece of paper and ink is extra 10 cents.The stamp and signature probably $500 to $1,000.Its a big ouch to any company and to a new one its major.Also could get a back charge for holding up the job till its fixed.

 

[allenwayne]

I have seen numerous trusses that were altered by the truss company on site ,where all that was done was a call was made a service tech showed up made the alteration and left no engineer ever visited the site or inspected the work done.
I have also seen a simple truss fail the frame inspection when a tail was cracked when off loaded.It`s a double edged sword but I agree with Jim.Don`t drill a truss or a paralam unless someone else takes the resposibility.We wire we don`t build or engineer what is built someone got the big bucks for that let them take the responsibility that goes with the big $$$$$$ they get.

 

[Jim W in Tampa]

A few weeks ago while doing some changes on one of our roughs i seen where one of our not so bright electricians had drilled a truss.Why i will never know and since it was already passed i took no action.If one 3/4 hole causes a structual problem we are all in trouble.Most things are over enginered by 200 % or more.Several holes in a row might be a problem.