Light Blocker Bars: U-Shape vs L-Shape – Which One Is Right for You?

by shin Lim

Looking for better blackout performance from your window treatments? Light blocker bars are a simple yet powerful solution to eliminate side light gaps and boost energy efficiency. In this post, we’ll walk you through the differences between U-shape and L-shape light blocker bars, how they work, and how to choose the best option for your shades or blinds.

What Are Light Blocker Bars?

Light blocker bars are slim channels that install along the sides of your window frame to block light leaks where shades don’t fully meet the wall. They're especially useful for blackout roller shades, where even a small gap can let in annoying slivers of sunlight.

U-Shape Light Blocker Bar: Best for Wind & Light Control

The U-shape design creates a channel where your roller shade fits directly inside, sealing both edges to minimize light and air movement.

Key Features:

  • Excellent wind resistance – roller shade is embedded within the bar

  • Superior blackout performance at both ends

  • Only compatible with roller shades - The light gap should be less than 3.81 cm (1.5"). Otherwise, it won't be suitable for your roller shade. 

  • U-shape bars are installed with screws at both ends by default, but adhesive strips can be purchased.
  • If ordering with blinds from us, we’ll pre-trim the bars to match your shade perfectly.

  • Available in multiple colors and aluminum material for durability

  • Made of premium aluminum alloy

Note: U-shape cannot be used with zebra, honeycomb, or Roman shades due to its embedding design.

L-Shape Light Blocker Bar: Versatile & Easy to Install

The L-shape light blocker bar is a more universal solution. It sits along the sides of the shade to block light gaps, but does not embed the shade itself.

Key Features:

  • Works with a wide range of blinds: roller shades, zebra blinds, honeycomb, Roman shades, and more

  • Blocks side light gaps effectively

  • Self-adhesive backing included by default for easy, tool-free installation

  • Can be trimmed or adjusted in height as needed

  • Lightweight and low-profile design

  • Available in multiple colors and PVC material

Measuring for L-Shaped Light Block Bar

  1. Measure the full height of your window frame where the bar will be mounted.

  2. Ensure that your roller shade width allows for the bar to fit on both sides.

  3. If ordering with blinds from us, we’ll pre-trim the bars to match your shade perfectly.

Note: Although it reduces light seepage, the L-shape does not block wind since the shade isn’t enclosed.

 

Need More Help? Feel free to chat with us – we’re happy to assist!

 

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