Drilling and wiring - Deal NJ

Packman951

Member
Location
Deal, NJ
Would like to know the code when drilling through floor joist for low voltage cabling?
the floor joist are engineered joist.

how big of hole can be drilled?
What's the max amount of cabling per hole?
does there have to be any separations between each hole?
 

GoldDigger

Moderator
Staff member
Would like to know the code when drilling through floor joist for low voltage cabling?
the floor joist are engineered joist.

how big of hole can be drilled?
What's the max amount of cabling per hole?
does there have to be any separations between each hole?
That will not be in the NEC, nor even necessarily in building code for an engineered joist as opposed to common timber.
I would look carefully at the documentation from the joist manufacturer instead.
There will be separate limitations for holes in the top and bottom plates versus the vertical web. The location of the hole is as important as the size of the hole.
 

chris kennedy

Senior Member
Location
Miami Fla.
the floor joist are engineered joist.
From the 2012 IRC

Chapter-5 Floors


R502.8.2 Engineered wood products.
Cuts, notches and holes bored in trusses, structural composite lumber, structural glue-laminated members or I-joists are prohibited except where permitted by the manufacturer?s recommendations or where the effects of such alterations are specifically considered in the design of the member by a registered design professional.
 
Here on the left coast, residential manufactured trusses usually come with pre-punched holes (the inner circle of wafer-board is still in the hole, but it just pops out.

Here, drilling / notching a truss is a good way to: 1) fail an inspection 2) cost yourself a ton of money replacing the truss(es) 3) lose a general contractor
 

infinity

Moderator
Staff member
Location
New Jersey
Would like to know the code when drilling through floor joist for low voltage cabling?
the floor joist are engineered joist.

how big of hole can be drilled?
What's the max amount of cabling per hole?
does there have to be any separations between each hole?
As noted you would need to consult with the joist manufacturer.

Welcome to the Forum. :)
 

kwired

Electron manager
Location
NE Nebraska
Here on the left coast, residential manufactured trusses usually come with pre-punched holes (the inner circle of wafer-board is still in the hole, but it just pops out.

Here, drilling / notching a truss is a good way to: 1) fail an inspection 2) cost yourself a ton of money replacing the truss(es) 3) lose a general contractor
There is a difference between a true "truss" member and a more solid "engineered joist" and an engineered laminated beam is yet another animal. True "trusses" you generally do not cut or drill at all without specific instructions from the truss designer on where or how to make such modifications, and even that is a little rare to have happen. Laminated beams are strict but usually can have some drilling allowances that do not have much weakening effect if done properly. The "TJI" engineered joists are more forgiving with drilling holes. I have heard of instances where you are allowed to remove the entire height of the webbing portion but only up to a certain width and you should never remove any of the top or bottom chord, unless maybe in a section that is not load bearing.
 
There is a difference between a true "truss" member and a more solid "engineered joist" and an engineered laminated beam is yet another animal. True "trusses" you generally do not cut or drill at all without specific instructions from the truss designer on where or how to make such modifications, and even that is a little rare to have happen. Laminated beams are strict but usually can have some drilling allowances that do not have much weakening effect if done properly. The "TJI" engineered joists are more forgiving with drilling holes. I have heard of instances where you are allowed to remove the entire height of the webbing portion but only up to a certain width and you should never remove any of the top or bottom chord, unless maybe in a section that is not load bearing.
I agree with you on everything except this. The closer to the centre of the span of an I-joist the bigger hole you are allowed to make, but no manufacture allows you to completely remove the entire web of an I-joist.
 

kwired

Electron manager
Location
NE Nebraska
I agree with you on everything except this. The closer to the centre of the span of an I-joist the bigger hole you are allowed to make, but no manufacture allows you to completely remove the entire web of an I-joist.
If you remove the entire "webbing" are you not centered and have made the biggest hole possible?:)

I honestly don't know if that information was true or not, but I can see it being possible but maybe with limitations. I think it was an HVAC guy that told me he can cut out all the height of webbing in some instances for his duct, and this was coming from a former construction guy turned to an HVAC guy so I give him more credibility then most HVAC guys on such a topic.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I have not seen engineered joists in years. I hate them because the holes never line up. I also drilled my own holes and kept them toward the outer third of the run centered in the height. If the engineered holes are allowed in those spots them I don't see why the holes I drill are any different
 
....I honestly don't know if that information was true or not, but I can see it being possible but maybe with limitations. I think it was an HVAC guy that told me he can cut out all the height of webbing in some instances for his duct, and this was coming from a former construction guy turned to an HVAC guy so I give him more credibility then most HVAC guys on such a topic.
I almost ended my post saying that it is a rumour started by tin knockers.

I wasn't always an 'electrician, I framed houses for many years. I have always been a dork though, so I read the paper work that came with I joists and all the brands had illustrations and details of the size of size of holes relative to the span, all of them also had a picture of cut out from top to bottom of the web with a big X through it.

I'm sure it is done and since houses are so over built I sure in a lot of those cases there is no real harm done.
 
Top