Problems with light infiltration?

Hey, Dwight Kopp here with Forgotten Mountain.

Fixing Light Leaks Around Window Treatments

So if you’re working with blackout shades, room darkening curtains, or inside mounted shutters, or even our own window grilles, there’s the chance that you might have light infiltration coming around the outside edge. Now, that usually happens because the window sashes marginally out of square, so the installation works great on the top, but not on the bottom. You’re going to have a sliver of light sneaking around the edge. So what we’re going to look at are some, hopefully some solutions that you can pull together at home to solve that problem.

Adhesive Foam Seal (with Partial Adhesion)

So probably the simplest option would be to use adhesive foam seal with a partial adhesion on the back. Now, generally, the foam seal comes in a roll. It’s usually a half inch, quarter inch wide, and there’s a piece of tape on the back that you peel off to reveal the adhesive, and then you put it on your application. In this case, what you’re going to do is turn it upside down and taking in an exacto knife or utility knife. If you want to cut that backing, that paper backing in half top to bottom, you’re not going to cut the whole seal in half just through the tape. So when you peel it off, only half of the backside is going to be exposed. Then you’re going to adhe that onto your grill. The overhanging piece that still has the facing will overhang your sash now, that way it won’t stick to your sash, it will stick to your grill and hopefully block out the light. Now, you’re going to have to experiment with that before you hit play because you’re going to want to make sure it doesn’t look really ugly.

Shadow Trim Frame

A second option would be to actually have us manufacture a shadow trim frame. So basically what we would do is create an exterior frame that mounts on top of the grille that overhangs the sash on the side. If you’ve got problems with light infiltration, this option is a little fussier and more expense, but certainly if you want to go that route, give us a shout. 

Fabric Light Flap

The last option would be to use a fabric light flap. So you’re going to use something like a blackout fabric or a flocked tape, and you’re going to glue that onto the grille, either on the glass side or the room side. Probably the room side is the best option because it can overhang the sash a little bit and hopefully solve the problem. Again, you’re going to want to be careful and make sure that it’s not going to look tacky when you put it in place. It should be a nice, clean solution. Most of these options are going to work best with the black grills similar to the color we see behind me, simply because most of the foam products that you get are either black or white, and I think the black is probably going to blend in a little bit better, but I would just check those materials first before you actually glue them on and make sure that it’s going to do what you want.

Anyway, I hope that helps. Feel free to reach out to me if you have any specific questions. Happy to help you troubleshoot or talk you through a solution.

BONUS:

**Measuring Tip **: Always measure all four glass edges — use the smallest measurement if your window isn’t perfectly square.

Window grilles offer a low-profile, removable, light controlling alternative to bulky treatments–and still let your windows shine!