Drilling Trusses

[SparkyAdam]

Hey forums, I'm looking at this giant truss in the garage of a home we are wiring. It's between the panels and the rest of the house. I can't go above it, as that's the wall on the second floor.

It has a tag that says do not cut or modify. I am pretty sure I can't drill this at all, right? Not even in the outer third?

Pictures won't upload here, they are too big. here is a link to what I am looking at (arrows will indicate the truss in the way):

https://imgur.com/a/AewXYVZ

 

[LarryFine]

I believe a row of spaced holes centered between top and bottom is acceptable.

 

[electrofelon]

I would say you should get approval to drill that. Shouldn't be too hard to track down the engineer from the truss company that designed those.

 

[Hv&Lv]

“Truss members shall not be cut, notched, drilled, spliced or otherwise altered in any way without the approval of a registered design professional,” according to the International Residential Code (IRC R802. 10.4).

It can get very expensive if you ask for forgiveness later.

 

[PaulMmn]

Hey forums, I'm looking at this giant truss in the garage of a home we are wiring. It's between the panels and the rest of the house. I can't go above it, as that's the wall on the second floor.

It has a tag that says do not cut or modify. I am pretty sure I can't drill this at all, right? Not even in the outer third?

Pictures won't upload here, they are too big. here is a link to what I am looking at (arrows will indicate the truss in the way):

https://imgur.com/a/AewXYVZ

Is that sheet of particleboard part of the truss, or something that the carpenters added?

 

[tortuga]

“Truss members shall not be cut, notched, drilled, spliced or otherwise altered in any way without the approval of a registered design professional,” according to the International Residential Code (IRC R802. 10.4).

It can get very expensive if you ask for forgiveness later.

Many years ago I drilled thru some trusses like that and it did not get approved.
I had to re-route in a surface conduit sleeve and have the truss repaired.

 

[Dennis Alwon]

Never drill a truss unless an engineer allows it because you may have to rip it out. I can be a pita but that is what it is. We had one in a garage and we had the engineer tell us it was fine to drill a few 1/2" holes.

 

[Dennis Alwon]

Many years ago I drilled thru some trusses like that and it did not get approved.
I had to re-route in a surface conduit sleeve and have the truss repaired.

I left my job for an hour and told my guy to not drill the truss. I came back and guess what he did? Fortunately, he drilled it directly over a bearing wall so I wasn't worried about it. Sweat.......

 

[curt swartz]

Fortunately, he drilled it directly over a bearing wall so I wasn't worried about it. Sweat.......

Trusses are supposed to be supported on the ends only. They are never supposed to sit on any interior walls.

Roof trusses move up an down depending on roof loading and temperature. There is supposed to be ~1/2" space from the bottom of the truss to interior walls to allow for the movement. Engineers claim an interior wall preventing the truss movement can cause the truss to fail. I have not seen it happen but..........

May people think the bottom chord of the truss is like a standard ceiling joist with the force against the member is going down. The force is actually horizontal similar to a post tension cable

 

[LarryFine]

Is that sheet of particleboard part of the truss, or something that the carpenters added?

It's a joist behind the trusses. See additional pics in the OP's link.

 

[curt swartz]

Is that sheet of particleboard part of the truss, or something that the carpenters added?

That is OSB not particle board. Its not part of the truss. It is the center web of the TJI floor joists.

 

[acrwc10]

I believe a row of spaced holes centered between top and bottom is acceptable.

Never drill a truss without the approval of the truss manufacturer. They even put a label on it saying not to drill it. When you have to go to them later for a fix, they go overboard. the last time I saw a "fix" from the truss company it was for a few 7/8" holes and the fix was a 12' 2"x4" nailed to the side 2" on center the entire length of the 2x4.

 

[SparkyAdam]

Never drill a truss unless an engineer allows it because you may have to rip it out. I can be a pita but that is what it is. We had one in a garage and we had the engineer tell us it was fine to drill a few 1/2" holes.

I Was afraid this was the answer. @@@@ I have to get two 200 amp panel feeders across that somehow.

Fml

 

[LarryFine]

How about at the ends of the trusses, near the eaves?

 

[NoahsArc]

Can't go around inside the walls? Sort of out of options if over and through are shot, and I'm guessing under is objectionable.

 

[tortuga]

I hate it when plans are not designed with mechanical and electrical chases.
If they want a panel there they need to provide you a chase or live with surface conduit.

 

[gadfly56]

Not for nothing, and maybe it's an artifact of the angle of the pictures, but I see some clear space above the truss, very near the ceiling. Why can't you hop up there and then come down?

 

[rc/retired]

Trusses are supposed to be supported on the ends only. They are never supposed to sit on any interior walls.

Not true! I've inspected many trusses that have had at least 4 concentrated points of load.

Ron

 

[rc/retired]

Trusses are an engineered system. Any modification requires an engineered analysis.

Ron