How to Install Trunk & Door Weatherstrip Extrusions
Applies to: Universal-fit extrusion-style weatherstripping (sold by the foot or in kits) for trunks and doors—typically glue-on seals without pre-installed clips.
What You'll Need
- 3M Black Weatherstrip Adhesive (GL-11)
- Trim removal tools (GL-30)
- Plastic scraper or putty knife
- Rubbing alcohol and clean rags
- Painter's tape
- Sharp scissors or pruning shears
- Nitrile gloves (GL-10)
đź’ˇ Tip: Our Complete Installation Kit (GLK-1) includes the adhesive, gloves, and trim tools in one convenient package.
Step-by-Step Installation
1. COMPARE Before Removing
Hold your new seal next to the old one:
- Profiles should be similar (old seals flatten over time—new ones are taller)
- Check that length is adequate
- Identify which way the sealing lip faces
2. REMOVE Old Seal
- Start at the splice joint (usually at bottom)
- Use a plastic trim tool to pry up gently
- Pull slowly to avoid tearing
3. CLEAN Thoroughly
- Scrape off all old adhesive residue
- Clean the channel/groove with rubbing alcohol
- Let dry completely
⚠️ Critical: New adhesive won't bond well over old adhesive. Take time to get this right.
4. DRY-FIT First
- Lay the new seal in position WITHOUT adhesive
- Make sure it follows the contour naturally
- Mark where you'll need to splice/cut
5. PLAN Your Starting Point
| Application | Start Here | End Here |
|---|---|---|
| Trunk | Center top (above lock) | Bottom center |
| Door | Bottom of door | Bottom of door |
Starting at the bottom keeps the splice joint at the least visible location and where water is less likely to enter.
6. APPLY Adhesive & Install
Work in 6-12 inch sections:
- Apply thin bead to car body
- Apply thin bead to back of seal
- Wait 3-5 minutes until tacky
- Press seal into position firmly
- Use painter's tape to hold
- Move to next section
7. SPLICE the Ends
- Allow 1/8" extra material at the joint
- Apply adhesive to both cut ends
- Butt ends together firmly
- Use sharp scissors or pruning shears for clean cuts
8. CURE Before Use
- Leave trunk/door open for 1 hour minimum
- Full cure: 24 hours
- Don't slam—close gently until cured
Trunk vs. Door Differences
| Feature | Trunk Seals | Door Seals |
|---|---|---|
| Starting point | Center top | Bottom |
| Splice location | Bottom center | Bottom |
| Adhesive coverage | Full length | Full length |
| Drying time before closing | 1 hour | 1 hour |
| Special consideration | Don't pull tight—let it relax into shape | Test door closure before final glue |
Troubleshooting
| Problem | Cause | Solution |
|---|---|---|
| Seal won't stay in place | Surface not clean, adhesive not tacky | Re-clean, let adhesive tack properly |
| Seal is too long | Normal—extrusion sold with extra | Trim at splice point |
| Seal is too short | Wrong part or stretched original | Verify part number; contact us |
| Ends won't meet cleanly | Uneven cuts | Use sharp pruning shears, cut squarely |
| Water still leaks | Gap at splice, seal not compressed | Check splice joint; door/trunk may need adjustment |
Pro Tips from the Experts
- Don't stretch the seal as you install—let it lay naturally
- Work on a warm day (60-90°F) for best adhesive performance
- Keep the other side intact as a reference when doing doors
- Use Krazy Glue for corners if you need to miter/join sharp angles
- Test-fit without glue first—always
Jan 8, 2026
