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

I'd check with an engineer.

But, normally, you could tie the plates together horizontally with a tie plate that would help retain the structural integrity of the building should your holes be large. It's not so much the load bearing that is affected as the lateral tension.

http://images.homeandbeyond.com/prod-0090821-zoom.jpg

Building codes differ, call your local building inspection office. They are often very helpful over the phone.

Current guidelines limit holes to 1/3 the lumber's nominal depth. For a 2 x 4 that is 3.5/3 or 1 3/16" When more than one hole is drilled they must be staggered.

In older homes of course larger holes are common. Just think about the vent stacks from plumbing fixtures.

Top and bottom plates do not normally experiece lateral loads. The outward thrust of a roof is countered by the rafters in tension. The wall only carries a vertical load.

Actually I don't think there is any limit to the size of a hole in bottom plate as long as both sides are independently secure.

If there was a limit you would never be able to have a gap for a door in a load bearing wall.

Building codes differ, call your local building inspection office. They are often very helpful over the phone.

Current guidelines limit holes to 1/3 the lumber's nominal depth. For a 2 x 4 that is 3.5/3 or 1 3/16" When more than one hole is drilled they must be staggered.

In older homes of course larger holes are common. Just think about the vent stacks from plumbing fixtures.

Top and bottom plates do not normally experiece lateral loads. The outward thrust of a roof is countered by the rafters in tension. The wall only carries a vertical load.

I am not a house builder nor am I a residential inspector (Commercial Contractor and Engineer) but if that is the code it would be hard to plumb a house. You could not install an insulated water line in any 2 x 4 walls and you would not be able to run any vent pipe in a 2 x 4 wall. Could that be the code for holes in joists rather than plates? That would make sense to me. Also the outward thrust of a roof is countered by the joists in tension or the bottom cord of the trusses also in tension, not the rafters.

Actually I don't think there is any limit to the size of a hole in bottom plate as long as both sides are independently secure.

If there was a limit you would never be able to have a gap for a door in a load bearing wall.

Not the same thing. A header is installed over any opening in a load bearing wall.

OP use some common sense, it would be best not to drill the hole right be side a stud or column (unless the stud is located right over a joist). If you are cutting a section of the plate out be sure to nail the loose ends of the plate to the subfloor.

I am not a house builder nor am I a residential inspector (Commercial Contractor and Engineer) but if that is the code it would be hard to plumb a house. You could not install an insulated water line in any 2 x 4 walls and you would not be able to run any vent pipe in a 2 x 4 wall. Could that be the code for holes in joists rather than plates? That would make sense to me. Also the outward thrust of a roof is countered by the joists in tension or the bottom cord of the trusses also in tension, not the rafters.

Your points are well taken. Let me say that my post was careless:o.

Here are the rules for Lompoc CA (http://www.ci.lompoc.ca.us/departments/fire/handouts/cutnotc2.pdf)and as far as I know fairly typical. The maximum hole size is larger for interior non-bearing walls. The figure I gave is for bearing or exterior walls.

In my location the buiding inspector's only concern about interior non-bearing walls is that they are not so weak that they might fall over.

I was also careless in my terminology about rafter/rafter ties/ vs. joists. But the major point was that the plate is not there to counter a major lateral thrust.

Thanks all for your insight. I took another look yesterday evening and drilled a couple of test holes. It's quite strange, actually (to me anyway), because one of these walls is an exterior wall and another one is the wall between the living area and the garage that bisects the house. I expected both of these to be "weight-bearing", but it looks like neither one is. Both wall plates appear to be immediately next to, not on top of, concrete basement walls. So, in other words, if you looked at a cross-section of it from outside on the left to inside on the right you have concrete basement wall from the basement floor to the basement ceiling, then the main floor subfloor, then the main floor base plate and wall (the one I want to drill into) from the subfloor to the main floor ceiling but that wall doesn't start on top of the top of the concrete basement wall, it starts above (separated by the subfloor) and just next to (inside) the concrete basement wall.

So, if I'm in the basement, I can drill straight up through the subfloor about 2 inches away from the concrete basement wall and be smack dab in the center of the wall I want to be in. This is quite surprising to me, but I'll take it since it seems that judging from the advice above and some advice I've gotten elsewhere, I can put several sizeable holes in the plate underneath a single stud cavity (so long as I don't sever the entire plate) and be fine. What I'll actually probably do is notch out about a 12" long by 1-1/2" to 2" wide cavity in the middle of the plate and just use that. anyone see a problem with that?

Thanks all!

--Mav

I think you guys are way over thinking this. I am not a structural engineer either but I would not think that boring a couple 1" holes through the toe plate between a joist cavity is going to cause any significant structure problems. I have done this several times eventhough I have 2"x6" exterior walls but I used a 1" or equivalent boring bit. Just use the electrical chase for a guide for your hole alignments.
The problem I encountered was batt insulation which can be a real pain in the ***.

Not the same thing. A header is installed over any opening in a load bearing wall.

That is not the same thing either, that is to transfer the weight of the missing studs to the header and jack studs.

When you are drilling a hole in the bottom plate as long as both adjacent studs are secured there is negligible change in the load bearing capability.

However it seems if the hole is bigger than 1 3/4 inch they may want a steel plate added.(according to the guys who sell the steel plates)

See pages 4-5 of:

http://www.strongtie.com/ftp/fliers/F-REPRPROTECT07.pdf

Mav, being directly over a concrete foundation wall has nothing to do with whether it's load bearing (think pyramid construction) . Unless your house is post & beam construction any exterior wall is probably load bearing.

That is not the same thing either, that is to transfer the weight of the missing studs to the header and jack studs.

When you are drilling a hole in the bottom plate as long as both adjacent studs are secured there is negligible change in the load bearing capability.

However it seems if the hole is bigger than 1 3/4 inch they may want a steel plate added.(according to the guys who sell the steel plates)

See pages 4-5 of:

http://www.strongtie.com/ftp/fliers/F-REPRPROTECT07.pdf

Nice link. that's exactly the type of info I was looking for. I think I'm going to notch the bottom plate 1-1/2" deep and 6-8" wide. That should be enough clearance to get all of my cables through comfortably (and there are A LOT of them).