Ser through the Attic

[ActionDave]

...I guess one argument is that floors are typically designed for sturdiness and "feel" and this puts them very much above the strength they would need to not structurally fail

Correct, there is a difference between the strength needed to carry the load and the stiffness needed to keep the China cabinet from rattling whenever someone walks across the room.

"rule of thumb framing" is typically way overkill.

Even more correct. And the thing is the thumb keeps growing. At one time 2x8 headers was standard so 2x10 was better for mine's bigger than yours crowd. When 2x10s became common folks started using 2x12s, then LVLs and so on. I call it Big House Disease.

 

[electrofelon]

Fwiw the IRC does have substantial restrictions on holes in sawn members, but they are rarely followed or enforced.

 

[electrofelon]

Even more correct. And the thing is the thumb keeps growing. At one time 2x8 headers was standard so 2x10 was better for mine's bigger than yours crowd. When 2x10s became common folks started using 2x12s, then LVLs and so on. I call it Big House Disease.

And they don't think about all the heat loss thru that additional framing. Its rather sobering to calculate the heat loss thru framing members and compare it to the hest loss thru the insulated bays. I am suprised how infrequently i see advanced framing used (never).

 

[Dennis Alwon]

I am not really disagreeing, just that logically I wonder why why can drill pretty much anything else with just about no rules or oversight whatsoever but drilling a truss is the 8th deadly sin. I did a house that had an engineered framing package and me and the HVAC guy had to drill tons of holes through TJI's, PSLs, and LSL's. He had to drill lots of 6 inch holes for ducting. We had the allowable holes sheet from the manufacturer and it was amazing how much material we we allowed to remove. I guess one argument is that floors are typically designed for sturdiness and "feel" and this puts them very much above the strength they would need to not structurally fail (although in this case, some of the PSL's were supporting walls above them). But then there are rafters and collar ties which again no one blinks and eye at drilling. Perhaps the argument here is that trusses are engineered closer to to design limit where as "rule of thumb framing" is typically way overkill.

Engineered beams are quite large but drilling a 2x4 truss with a 3/4" hole can weaken the truss considerably. I left a guy on a job and told him not to drill a truss. I came back and he drilled the truss. Fortunately, it was over a wall so the structural integrity was not compromised. I was pretty peeved.

 

[Dennis Alwon]

Fwiw the IRC does have substantial restrictions on holes in sawn members, but they are rarely followed or enforced.

Maybe where you are that is true. Not here--If they see it you will have to fix it. Usually, 5/8" or 3/4" holes are not an issue thru stick built framing but there is a chart for what size hole is allowed based on the dimension of the wood.

Maybe easier to see this one

 

[roach1521]

Pretty much is why I was asking, the cable is going to have to be laid on the truss or strapped to the truss at the roof level both in the Attic I don't think I would really like to drill any of it

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