Drilling Holes in Structural Wood Beams for Electrical Wires

Drilling Holes in Structural Wood Beams for Wires

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If you are brand-new as an electrician, it’s VERY important you are aware of a structural support beam.

If you don’ know, don’t drill, and ASK YOUR FOREMAN RIGHT AWAY!

These beams are CRITICAL to a building’s strength when building a multiple-floor building.

As an electrician, we have know what we’re allowed to drill through, because we have to drill TONS of holes for all our various wires.

Examples of Structural Wood Beam:

Structural Support Beam (Laminated Beam.. or LVL Beam)
The yellow beam is a structural support beam. They are sometimes different colors, and can be termed as LVL (Laminated veneer lumber), or Engineered Support Beam. Also notice the other ceiling joists attached to the yellow support beam with ceiling joist hangers!!!

Now, there are rules for drilling through a structural wood beam, which I cannot repeat here as I’m not qualified for that. But what I will tell you is how you go about getting approval to drill through a wood beam.

If your building is full of support beams, the first thing you should do is contact the structural engineer. You NEED them to sign-off on any papers before you go ahead and drill. Sometimes they can take awhile to get back to you, so if you get on this ASAP, you’ll be able to get your crew moving faster.

Drilling into a support beam without approval is not just a little mistake.

If you drill into a support beam it can compromise the integrity of the building. If the building is already 3 to 4 levels high, and you drilled through a support beam incorrectly on the first level, it is REALLY hard to replace!

It involves adding additional pieces of wood to bear the support that the single LVL (support beam) was engineered to do.

Typically you can drill “the lower or upper third of the beam”, but it has to be within a certain distance from the ends, a certain size of hole, and some other rules. Again, do not listen to this regarding drilling into a support beam.. GET APPROVAL BY A STRUCTURAL ENGINEER BEFORE DRILLING!

Can I Drill Through a Support Beam?

An example of a hole drilled in a ceiling joist for electrical wire (looks like some spiders have been lurking…) .. this is not showing an example of a real support beam hole.. this hole is too close to the top.. I didn’t do it, I swear! 😁

With the structural engineer’s approval on your job site, which they have SIGNED-OFF ON PAPER (not just a verbal yes), then yes, go ahead!

If they have not signed-off explaining how you can drill into a structural beam, DO NOT RISK IT.

Structural engineers can request different rules and techniques. This is why it’s VERY important you ask THAT structural engineer’s approval on that jobsite. (You will not be able to use the excuse, “That’s how we did it on the last job..”). A structural engineer signs-off their life essentially, and it’s important you respect that, and follow their standards.

By getting approval, and it will save yourself A LOT of money, errors, and embarrassment.

What is a Structural Wood Beam?

Now, not to be confused with a “load bearing wall”, the support beam goes on top of these load bearing walls.

Showing the Top Plate of a 2x4 Wall which electricians should never staple their wires to!
Even though this wall is load-bearing, it is not holding up a structural support beam. (Used simply for demonstration purposes showing a load-bearing wall.. notice the ceiling joists on top of the wall, holding the weight!)

For the most part, we are able to drill through studs inside a wall to pull our wires. But when it comes to a structural support beam, you should immediately stop and know that jobsite’s rules for drilling through beams.

The easiest solution is going around the support beam with your wire. Sometimes it will be a little bit longer of a wire pull, but it will save you a lot of time, and allow you to sleep easier at night 🙂.

How Do I Know if it’s a Structural Support Beam?

Most of the time it’s REALLY easy to identify a support beam.

They can be yellow, orange, but sometimes they can be a little hard to tell!

A structural support beam is a specially engineered piece of wood, so it’s either laminated pieces of plywood together, or it can be a bunch of wood chips. Generally though, when you look at a support beam, you can tell that it is quite different from the rest of the ceiling joists in terms of color, and is usually thicker than other beams in the area.

Another clue to know if it’s a support beam is there may be many joist hangers nailed to it for other ceiling joists to be installed.


If you are just at home doing a renovation, I advise you to seek professional advice before you drill a hole for your wire through a support beam.

The easiest solution is to just find another wire path, and avoid the structural beam all together.

If you are working for a company, especially on a commercial job site with multiple floors and occupants, only drill through a support beam once you have your structural engineer’s SIGNED-OFF written approval in DETAIL about how to go about drilling into a wooden beam that is critical to a building’s weight load.

This is wise advice which has allowed me to never get in trouble drilling into the wrong things 🙂.

If you are looking at your architectural prints or electrical prints, it may not show that the beam is in the way until you get out in the field.. so make sure to plan accordingly out there.

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