I have a flat roof territorial style home with 2 x12 ceiling joists though
out the home. This is also a slab home...so no basement or attic to work
If I run additional electrical outlets/circuits/lines...can I drill a 1/2 to
3/4 inch hole along the path of my wiring in the ceiling joists to extend my
romex to whatever location is planned ?
Otherwise...how do you do something as simple as installing a ceiling fan
circuit in any room ?
Thanks, Tim R
It can be done, HOW EVER drilling holes in the middle of a bearing span is
NEVER a good idea.
everything you drill will be come a 2 x 10. Better get someone to look it
Surface conduit, wiremold can be used.
You do know that a ceiling fan box is a special box attached to the
If this were true, then electrical work in much of America would become
a big deal. Drilling a small hole in a 2X12 doesn;t make it a 2X10,
any more than the occasional knot or other imperfection in lumber used
The top of a 2x12 is in compression (it is being pushed together). The
bottom in tension (it is being pulled apart). The center just keeps the
top and bottom separated. Note how an I-beam is construted with almost
all the material at the top and bottom, or a bar-joist with minimal
material in the center. Drilling in the center, or away from the edges,
of a 2x12 does not affect its strength - it does not take much to keep
the edges separated. Notching an edge has a major affect on the strength.
Code does limit the amount of cross sectional area that can be removed by a
hole (sorry I forget the limit but it should be well within what you
Incedently, notching is generally worse than holes WRT loss of structural
support. Far less notching is allowed than a hole.
If these beams are exposed, it would probably look better with a conduit
even though that is not required. Running along the wall then against the
side of one joist would also limit the visible portions of the run and
eliminate most of the holes for just a few $ more in wire and staples. One
could even nail up some furring strips to form a channel then cover with
some trim to completely hide the wire. Just some more ideas
Just for added thought..
Romex or at worst conduit can be hidden behind moulding, either
baseboard or crown or anything else you like. There are also commercial
products that are moulding raceways and have seperated sections for low
and high voltage cables. I don't recall any names but try Leviton.com
Here is a link to the joist boring guidelines:
In general, bore holes in the center of the joist, not near the top or bottom,
and it is better to place them closer to the ends of the joist rather than out
in the middle of the span.
Is this true for solid wood joists? It is definately NOT true for I-joists.
For I-joists, you can put a hole up to 1.5" in diameter anywhere you
please - in fact, they come wth pre-stamped 1.5" knock-outs about a foot
apart all along their length.
For larger diameter holes, there are guidelines as to how close you can
be to a bearing surface - the larger the hole, the farther you have to be
from a bearing surface.
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