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Maximum Hole Size through Bottom Plate

Posted by mvdyk03 (My Page) on
Wed, Aug 22, 07 at 13:47

I cannot for the life of me find the answer to this question. I am undertaking retrofitting/converting my first floor family room into a home theater room; to keep it "clean" all wiring will be "in wall" (coming "out") only at the wall-mounted TV, the wall-mounted speakers, and the A/V Rack.

The "video run" from the A/V rack to the TV presents somewhat of a problem since I need to run SEVERAL (component, composite, HDMI, coax, etc.) low voltage cables from my A/V rack to a box behind where the TV will be mounted. This will be accomplished by going down through the bottom plate in the wall behind the A/V rack, over in the basement (between the floor joists and the drop ceiling) and back up through the bottom plate of the wall behind the TV.

Now, here's the question. Since I'd like all of the wires to terminate in the one multi-gang box on each end, how big or how many holes can I put in the bottom plate of one construction bay (i.e. the space between two adjacent studs) before I need to worry about causing a structural integrity problem? Both of these walls are weight bearing, standard 2x4 construction.

Thanks in advance!!

--Matt


Follow-Up Postings:

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RE: Maximum Hole Size through Bottom Plate

Load bearing means that the wall is probably over double joists or similar support. Drilling them needs to be minimized. Drilling the smallest possible holes in the upper portion of the joists does minimal damage. Coax will fit easily in a 3/8" hole. Drilling at an angle so that the hole comes out on the side of the joists about 2" or 2 1/2" from the top should be OK. Typically, 4 such holes would be the most I would do without reinforcing the joists. I suggest getting a good framing carpenter to look in person and make suggestions. Can you go up or laterally? Can the holes be placed nearer a support for the joists? Limiting drilling to the upper third of the joist height remains important.


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RE: Maximum Hole Size through Bottom Plate

I'm not sure I follow. I don't need to go through any joists since I'm going to run them laterally *under* the joists (but above the drop ceiling) in the basement. I'm really questioning how many (or how big) holes I can put in the bottom plate of the wall in which the cables will be run.

That is, here's the "run": (1) wall outlet box --> (2) vertical run down through stud/construction bay to base plate --> (3) through base plate --> (4) horizontal run down *under* floor joists but *above* drop ceiling in basement --> (5) through another base plate --> (6) vertical run up through another stud/construction bay --> (7) wall outlet box on other side of room.

How big can the holes for (3) and (5) be?

Thanks!

--Matt


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RE: Maximum Hole Size through Bottom Plate

I'll go out on a short limb for you as I do not know the 'official' answer since this is actually a building code question; not an electrical one.

However, assume you take worse case scenario and completely remove the whole bottom plate between the studs (e.g. essentially what happens when oval ductwork is installed, right?) Are you left with a significantly less structurally sound wall? Not likely as long as it isn't in the last cavity of the wall or you don't have to remove any lateral blocking. The vertical loads are transfered along the sole plate evenly into the floor underneath. Therefore, drill them as big as you want since anything less than the full width of the stud is still transfering the minute horizontal shear loads - just use strike plates as required.


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RE: Maximum Hole Size through Bottom Plate

What is under the shoe "baseplate"? A load bearing wall sits on more than the subfloor. Lets head downward. Stud cavity, then the shoe plate, then the subfloor, then ?, then basement. What is between the subfloor and the basement directly under that wall? How was it determined that it is a load bearing wall?


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