If you have a large or non-standard door—such as an airport hangar, service garage, warehouse, or oversized commercial door—one of our pre-sized brush seal kits may not fit your opening.
Instead, you can order Flex Brush by the foot and compatible aluminum retainers separately. This allows you to choose the brush length, bristle size, and retainer profiles that work best for your door.
1. Measure Your Door and Gaps
You'll need two types of measurements:
Door dimensions: Measure the width across the top and the height of both sides. These measurements tell you how many feet of Flex Brush and retainer you'll need.
Gap size: With the door closed, measure the gap between the door and where the brush retainer will be mounted. Check several points along the top and sides, since the gap may vary.
Your door dimensions determine how much material to order, while your gap measurements help determine the bristle length.
2. Choose Your Flex Brush
Choose a bristle length that spans the gap and makes light contact with the closed door without excessive compression.
Action Direct offers two Flex Brush systems:
- Standard Flex Brush: Available in 1", 1-1/2", 2", and 3" bristle lengths and fits Standard #4 retainers.
- Slim-Line Flex Brush: Available in 1/2", 3/4", 1", 1-1/2", and 2" bristle lengths and fits Slim-Line #2.5 retainers.
Standard and Slim-Line Flex Brush use different retainer sizes, so make sure your brush and retainer are compatible.
3. Calculate How Much Flex Brush You Need
Add the areas you're sealing:
Top width + Left side height + Right side height = Total Flex Brush needed
For example, a 20' wide door with two 16' sides would require approximately 52' of Flex Brush.
Flex Brush can be ordered by the foot and arrives as one continuous piece that can be cut to fit each section of the opening.
4. Choose Your Retainers
The retainer holds the brush in position against the door. Depending on your opening, you may need a different retainer profile for the top than you use on the sides.
As a general guide:
- 45° retainers are commonly used for sectional overhead garage doors.
- Straight retainers are commonly used for rolling steel and corrugated doors.
- Offset retainers can help when the mounting surface doesn't line up directly with the area you need to seal.
Look at the mounting surface along both the header and side jambs and choose the profile that allows the brush to lightly contact the closed door. Don't assume the same retainer profile is required around the entire opening.
Retainers are sold in 4'6" sections and can be trimmed during installation.
Need Help Choosing the Right Brush and Retainers?
For large or unusual openings, we're happy to help you determine the best combination before you order.
Have the following ready when you contact us through our Contact Us form or Live Chat:
- Door width and height
- Gap measurements along the top and sides
- Photos of the full door opening
- Close-up photos of the header and side jambs where the retainers will mount
These details will help our team recommend the right Flex Brush, bristle length, and retainer profiles for your application.
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