Re: Hole Diameter for running cable

["Jeff Volp" <JeffVolp@xxxxxxx>]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote in message
news:6N-dnasVM6_k9PDYnZ2dnUVZ_q2dnZ2d@xxxxxxxxxx
> Bob Bass wrote:
>
> Thanks.  I'm always reluctant to drill through joists and wonder whether
> some of the engineers here could suggest what size plywood "cladding"
would
> offset the loss of structural integrity by drilling 2" holes in 8 or 10"
> joists.  I've been laying out a CCTV upgrade and with RG6 going
everywhere,
> the holes add up.

I know what you mean about holes.  The main trunk down our center hallway
fills two 1" diameter holes.

Maximum stress on a joist is at the top and bottom surfaces.  All the center
really does is to keep the top and bottom aligned properly.  It does not
compromise the strength of a joist at all if you drill a hole through the
center of the beam.  While it may be permitted, I would avoid cutting ANY
notches into the top or bottom surfaces.  That will severely compromise the
strength of the beam at that point.

Today's engineered joists are I-beams with structurally strong top and
bottom sections separated by flimsy wafer board.  There are even pre-stamped
knockouts in that center section.  Those fragile looking assemblies can
support incredible spans.

Jeff