Yes—an exterior side garage door should have a proper threshold installed. It’s considered best practice for any exterior entry door, including those on a garage.
What the Threshold Does
A threshold (the raised piece at the bottom of the door frame) serves several functional purposes:
- Water management
Prevents rainwater from blowing or running under the door, especially since garage slabs often slope. - Weather sealing
Works with the door sweep to create a tight seal against drafts, dust, and temperature transfer. - Pest control
Helps block insects and rodents from entering through gaps. - Structural support for the door seal
The door sweep compresses against the threshold to maintain a consistent seal.
Typical Construction
Most exterior doors use an aluminum threshold with a rubber or vinyl seal, often:
- Adjustable with screws to fine-tune the height
- Around ½–1 inch high
When a Threshold Might Be Missing
Sometimes you’ll see a door installed directly on the slab when:
- The slab was poured flush with the doorway
- The installer tried to avoid a step hazard
- It was installed as a quick builder-grade setup
However, without a threshold you’ll usually get:
- Visible gaps
- Drafts
- Water intrusion during storms
- Pest entry
Quick Visual Check
A properly installed door should have:
- A visible threshold piece under the door
- A door sweep contacting the threshold
- No visible daylight underneath when closed