Sealing Electrical Outlets While Building A Custom Home
Hey everyone! Air and water sealing electrical outlets in your custom home is essential to ensure longevity. You don’t want air leaks or water intrusion, so we’ll show you several options. We have four or five different types of boxes to examine, and we’ll explain why we chose what we did for this application.
We’ll also show you the electric outlets we used on this penetration and the steps we took to install them. Let’s get started!
Option 1: The Standard Box
The first option is a common one—a standard electrical box that’s 20.3 cubic inches. You’ll often see this installed on a home’s exterior, where a hole is cut into the wall, and the box is placed inside. However, sealing it correctly is a challenge. You can use ZIP tape, caulking, or other sealing methods, but this is the least desirable option.
While we did use this in some of our porch soffits where air sealing wasn’t necessary, we recommend avoiding it when possible.
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Option 2: The Arlington Inbox
The next option we considered but didn’t use was the Arlington Inbox. Arlington has several great products, and we did use some of their other offerings, but this specific one had a few drawbacks.
One advantage of this box is that it allows the outlet to be recessed inside, meaning most of your siding, brick, or stucco will cover it. However, we observed issues in other builds where the box was installed too far out, causing the hinges to hit the exterior and preventing it from opening fully.
Additionally, these small plastic tabs on the edge could break over time. If that happens, replacing the cover is difficult. Due to these concerns, we decided against using it.
Option 3: The Arlington FR101F
For electrical outlets, we chose the Arlington FR101F. This electrical box is adjustable, featuring a one-and-three-eighths-inch standoff that allows installation flexibility. It can be flipped to provide a five-eighths-inch standoff, and an adjustable ring can increase the depth further.
We liked this option because:
- It provides the necessary depth to connect multiple wires.
- It includes a seam for air sealing.
- The back can be foamed, and the front has a flange that can be flashed to the sheathing.
- It creates a watertight seal, similar to a properly installed window.
Behind me, you can see this box installed. I’ll go through the steps we took after showing some other options.
Light Box Options
For light fixtures, we considered a few different Arlington products:
- Arlington FR405F – This is ideal for situations where fewer wires are needed. It has a one-and-three-eighths-inch standoff, adjustable to five-eighths-inch. It’s a significant step up from a pancake box, providing enough space to make connections while allowing for proper air sealing.
- Arlington FR420F – This deeper box is useful when more wiring space is required. However, installing it requires cutting the back of the sheathing, so proper air sealing and flashing are critical.
Final Installation Process
We installed the Arlington FR101F using the following steps:
- Cut the Opening – We marked the location and cut a hole in the OSB sheathing.
- Apply ZIP Stretch Tape – We wrapped the tape around the opening to create a waterproof barrier.
- Apply Liquid Flash – We applied liquid flashing around the back edge of the box before inserting it into the opening.
- Secure the Box – We leveled it and used screws to attach it to the sheathing.
- Final Sealing – We applied more stretch tape along the sides and top, ensuring no gaps for water intrusion.
- Add a Mounting Block – A five-and-a-half-inch-wide block was placed over the box, secured with custom-bent flashing.
- Final Siding Installation – Lap siding was installed, fitting snugly against the mounting block.
We repeated this process for all exterior outlets and light boxes to ensure proper sealing.
Which Electric Outlets Would You Buy?
We hope this helps you understand your options for air-sealing and water-sealing exterior electrical outlets and light fixtures. If you have any questions, drop a comment below.
If you want to build a custom home or an accessory dwelling unit (ADU), request a project consultation with us. Take a look at our comprehensive collection of similar videos on our YouTube channel, The Real Property Show.
