How do I seal the gap in vinyl siding left around a new, differently shaped outdoor plug cover?

Question

The house I recently bought had a pretty flimsy flat cover for the front outdoor receptacle. With the holidays coming up, I wanted to change the cover to something that would be waterproof even when in use, so I can set up some outdoor lights.

I removed the old cover and the J trim around it in order to make room for the new cover, which is slightly bigger and a slightly rounded shape instead of a rectangle. Now I'm left with a small gap in the siding around the new cover.

The plug is under a covered porch and right next to a pillar, so while this location doesn't get super wet, it's still definitely exposed to the elements (and it gets pretty cold here in southern Ontario). What can I do to seal the gap?

Answer 1

Your problem is the mismatch between the shape of the box you bought and the cutout you already have in your vinyl.

There are box extenders for vinyl siding that have zig-zag shaped backs to fit over the vinyl, but your vinyl is cut open too much for that, you'd have to replace a couple of pieces.

There are wet-in-use covers, like yours, that are designed for vinyl siding. They include an oversized flange with a channel around the outside that wraps around the front and back of the siding cutout. One of those would probably work well if you're willing to buy a whole new box.

If you want to use what you have, your best bet would be to buy a small piece of 1/2- or 3/4-inch composite board and make a custom box extender. Cut a rectangular piece sized to fit snugly within the vinyl opening so you can make a neat caulk line around it. Half inch board should be thick enough to mate with the vinyl at its thickest. Cut a rectangular opening in the middle of it the size of your box's mid-sized opening, that is the opening if you remove the snap-out piece that your outlet is currently mounted in. Then mount your box on top. The idea is to provide a nice surface for you box to mate with, and also a nice surface for your vinyl to mate with all around so you can caulk it neatly.

Answer 2

For a new box with no existing cut, you would add spacers on top of siding low spots and then mount to those spacers with just a drilled hole in the siding for the wire to penetrate.

If you have siding left over from way back, then use it to cover that cut. If not, then get some with as good a color match as you can manage, and then cover the cut with it. If it takes a top and bottom piece of siding to cover the scar, then cut them the exact same length and line up the sides so that any color mismatch looks relatively pleasing to the eye.

If your home has insulating foam beneath the siding, then you'll need spacers with 2 or 3 square inches of bearing to avoid crushing. If the substrate is wood, however, you can use nice cylindrical offsets (there's an actual product called an "offset" for this). Put spacers in the low spots of the siding and bridge them with a flat surface to mount your box onto, then remount the box. Don't forget to caulk the drilled hole with caulking designed for exterior use.

Personally, I have aluminum bar laying around and recessed screw cutting bits (wood bits work on aluminum), where I would use that stuff with aluminum offsets for a pretty job. Whatever you use, just be sure that the fasteners holding the flat mounting surface don't interfere with the mounted box.

Answer 3

Use a siding mounting block, assuming your cutout is less than 6x7.5.

https://www.homedepot.com/p/Novik-5-94-in-x-7-56-in-Polypropylene-Recessed-Split-Mounting-Block-in-White-146200001/313135264

If you need to this again in the future, here's a kit that includes everything (except the outlet):

https://www.amazon.com/gp/product/B07FWD3RCK