Bottom astragal (U-seal)
The thick rubber bulb running along the bottom edge of the door is called the bottom astragal or U-seal. It compresses against the floor when the door closes, sealing out water, leaves, mice, and cold air.
Standard U-seals last 5–8 years in Kansas before the rubber hardens, cracks, or shrinks back from the ends. Replacement is straightforward — slide the old seal out of the aluminum retainer, slide the new one in. Material runs $25–$50; with labor expect $80–$120 for the bottom seal swap.
Perimeter stop molding seals
The vinyl strips along the top and sides of the door opening — usually attached to the wood stop molding — seal the gap between the door and the frame when the door is closed. These deteriorate from UV exposure on the sun-facing side first; we often see one side bleached and brittle while the opposite side is still flexible.
Replacement requires removing the old strips, sometimes replacing or re-shimming the wood stop molding underneath, and nailing in new vinyl-edged strips. $150–$250 for a full perimeter seal job on a typical residential door.
Threshold seals for blowing snow and grade issues
If your driveway slopes toward the garage or your bottom seal can't fully reach the floor (uneven concrete, cracking floor at the door), a threshold seal — a thick rubber strip glued to the floor where the door closes — gives the bottom seal something flat and consistent to compress against.
We don't recommend threshold seals on every install (they can trap water if the garage doesn't drain right), but for north-facing garages that catch drifting snow, they're the difference between a dry garage floor and a slush puddle every February.
Why this matters in Kansas
Topeka winters routinely hit single digits and summers hit triple digits. A drafty garage on an attached home pulls 5–15% more on your HVAC year-round. For detached garages used as workshops, sealing is the difference between a comfortable space in March and a space you only use 4 months of the year.
Pest pressure is the other factor. Mice, snakes, and wasps don't need much of a gap. A bad bottom seal is the single most common entry point for mice in Topeka homes.