you can bore holes THROUGH the joists and run all the wiring through them. go 2-3" from the bottom of the joist.

when putting holes in joists though, never cut out more than necessary. every hole and notch weakens the joist at that point, so keep them to a minimum. a 1" hole in a 2x10 won't hurt, but several together in one area will. as will notching it out to run a 3" pipe thru it.

why not drop teh ceiling 4-5 inches and then you still have room to run anything want between the joist and dropped ceiling? you can drop it less than that if all you need to be able to do is fish cables. i have also seen people install a soffit at each end wher they can run between teh joist to one end or the other, then fish in the soffit to move 90 degrees to the joist.

Since it's your typical basement, headroom is at a premium. Giving up 4-5", while possible, would make for a cramped feeling. The 2" I'd give up with the 2x4s and sheetrock are about as much as I really want to give up own there.

The previous owner did a wonderful job at turning the joists into swiss cheese. Although a large number of wires ran along the perimeter, any time he wanted a light or a socket, he drilled holes and ran the wire straight from point 'A' to point 'B'. Nothing that appears dangerous from a structural point of view, but I would prefer to not add any more holes as that appearance could easily change.

I intend to run a significant number of coax cables (typically 2 per room), electrical wiring, low-voltage wiring, as well as cleaning up the piping (most of the piping is already tacked to the joists rather than through it).

So, any suggestions on how to protect all of it? If it's being done this way for remodeling, someone has to have figured out a way to protect it all.

"when putting holes in joists though, never cut out more than necessary. every hole and notch weakens the joist at that point, so keep them to a minimum. a 1" hole in a 2x10 won't hurt, but several together in one area will. as will notching it out to run a 3" pipe thru it."

Yes. From a structural standpoint as well you don't want to drill through the middle third of a joist (length wise, or height wise for that matter). From plate to plate, divide your joists into thirds and only drill through the first and last thirds. I've seen electrical inspections pass drilling thru the middle third but when the framing is inspected it could very easily fail if an electrician comes thru and starts drilling holes down the middle...

Actually, the proper drilling location (middle or end 1/3) 'depends'. Joists fail in the middle due to deflection, but they also fail on the ends do to shear. You cannot assume one is ok and the other is not unless you do the calcs or use the span tables w/ holes. Although, I believe all APA rated wood for joists can have up to a 1.5-inch hole bored anywhere along its length (except for the bearing points and certain distances from the top & bottom). Thus it wouldn't matter if it was middle or end 1/3's you drilled in if the hole is small enough. Concentrated groups of holes however are treated like one large hole encompassing the perimeter of the holes.

Of course you can always create a wiring chase if you don't want any more holes. I wouldn't lower the whole ceiling 2" or more for something that is only needed in a few select locations. Be creative with it. Turn it into a shelf, add rope lights, glass cabinets, or whatever. Don't think you need to be stuck with a plain old soffit.

AS liong as you stay away from the bearing points at each end, you can put an awful lot of holes in the middle (vertically on the face) of a joist without affecting the strength very much at all.

This is the median plane.

The force changes from tension on the bottom to compression on the top, and the stresses at this pointy are much lower.
For the ends you want to stay away form the area above the bearing point and inside a 45 degree line from the inner edge of the bearing to the top edge of the joist.

The exact median plane varies with the loads on the joist, but since joists are sized for a uniform load on the entire floor at the same time of 40 Pounds per Square Foot (PSF) live load plus 10 PSF dead load (first or main floor) and 30 PSF live and 10 PSF (second and other floors) it is very rare to come even close to loading a joist to the modern design limits.
Older houses may have undersized joists compared to modern design (even if they use full dimension lumber).

These numbers mean a 10 foot x 10 foot (100 Square Feet) room on a main floor is designed to carry over 5,000 pounds of total load (L+D) continuously.

Joist boring and notching is done all the time. Here's a list of rules for drilling and notching various framing materials - keep in mind they are by a building department concerned with structural members working even under adverse conditions

I also thought of this.... since the framing will be set off of the foamboard by say, 2", that will give me a bit of room to staple wires to the joists and keep them between the foamboard and the framing. No need for a soffit after all (at least for the wiring.

I vaguely recall some limitation to the number of wires that can run next to each other in an enclosed space while getting reacquainted with the NEC code, so I'll have to thumb through the little red book again.

Just drill the darn joists. I don't know why people get paranoid about this. I drill joists in every house I wire and have never drilled enough holes that the joists start sagging. I even have a special drill so I can stand on the floor and drill holes in joists 8 feet up without reaching. The rules I posted a link to are approved by most building departments and by the lumber industry.

Now, if you're considering installing 3 inch or larger plumbing pipe by drilling joists we might need to visit a bit. As long as the 2 inch from the edge rule is followed and the holes are spaced 3 diameters apart horizontally, almost an unlimited number of 1 inch holes could be bored without weakening the joist - or at least enough you can wire the house without worrying.

Of course, maybe all those building officials and engineers with untold thousands of years of experience with wood framing really don't know anything about it. If buying a house myself I certainly wouldn't be impressed by undrilled joists but would be marveling at the waste of wire by not doing so.

"I certainly wouldn't be impressed by undrilled joists..."

I would wonder what else might not be not up to code (unless they used running boards).
Drilling joists for wiring has been REQUIRED for many code cycles now unless you use running boards.
Old wiring might have been correct when installed (and remains grandfathered) but new wiring MUST be run in bored holes or on running boards.
Larger sizes may be run on the bottom of joists without running boards, but typical home wiring for general use circuits is not large enough to be exempt.

Shouldn't the holes be drilled dead center? I read another rule sheet saying the top 1/3 of the joist is in compression and the bottom 1/3 is under tension, so the best place is in the center of the joist.

READ THE LITERATURE FOR JOISTS ON THE LINK!!!!

There is no requirement to drill in the center, just a minimum distance to the edge. The rules on the site for joist drilling (Los Angeles Building Dept) are the same as those issued by the people who sell the lumber. This is a pretty universal guideline.

brickeyee, are you saying it's actually [u]against[/u] code to staple 15A/20A wires to the underside of the joist?

"brickeyee, are you saying it's actually [u]against[/u] code to staple 15A/20A wires to the underside of the joist?"

It has been for a while.
Either bored holes or running boards have been required for some time.
Code is at work.
I will try to look up the cite Monday.

Just so I'm clear, the wires will be run between the new framework and the foam board. This means once the gypsum board is installed, they'll be protected from the "outside" world by 2" of wood and plaster on one side, 12" of concrete block on the other, and 10"+ of joist from above. It would seem drilling holes in the new framework studs just to run the wire is redundant and less protected by being closer to the "outside" world (even if still to code depth).

But if the code speaks...

We had another thread here not to long ago that did the exact same thing you are doing. They ran the wire behind the new framing. I don't seem to remember anyone having an issue with that as long as there was clearance for the cable so nothing was pinched.

The rules are for wires run across a ceiling.
If you can fit the wires outside of the joists you would be OK.
This construction sounds rather odd, since joists are normally nailed to a band to keep them from twisting at the ends (along with cross bracing in the middle to share loading and prevent twisting there).
Without this fastening there are other structural issues since there is nothing to keep the joists vertical.

Joists support floors and ceilings, rafters hold up roofs.

What is preventing them from falling over or twisting?

Here is the other post with that foam and stud issue

Here is a link that might be useful: Prior Post

brick, the bands are somewhat deeply inset into the footers. It's a difficult thing to describe, but I'll try. I'm facing a concrete block wall in the basement, so the joists are the floorboards of the main floor. The joist bands attach the joists to the faceplate, but the faceplate board itself is set back from the inside surface of the blocks by a good 6"+. If the faceplate was closer to the surface, I would staple the wires to it. Since it's not, I have to staple to the bottom of the joists themselves. Since I'm setting the wall frame a couple of inches off of the newly installed foam, I now have a couple of inches of free joist space to tack to. I'm not really sure what I said to lead you to believe there were no supports...