Small insects, dust, dirt, or debris could be hiding under the door threshold.
A weatherstripping or door sweep should be placed under the exterior door threshold to prevent drafts and keep out moisture and pests.
threshold
to lock someone inside
A door threshold can have a wide price range, depending on the model of the door threshold and the material used. The price range of a door threshold is about: $30 to $50.
To install an under door threshold seal, first measure the width of your door and purchase a seal that fits. Clean the bottom of the door and threshold area. Attach the seal to the bottom of the door using screws or adhesive. Make sure the seal creates a tight seal when the door is closed to prevent drafts and improve energy efficiency in your home.
One can purchase a garage door threshold from Garage Door Fitters, Home Depot, Amazon, Wickers, Weather Stop and eBay stores. A garage door threshold helps to prevent rain that is driven by wind, dust, snow or dirt from getting under your garage door. This helps make your garage remain very clean and dry.
To adjust a residential entry door threshold plate you have to check for the location of cracks between an exterior door threshold and an exterior door on a sunny day. Get on your hands and knees in front of the door on the inside and look between the threshold and door to see where the sunlight comes through. A little light at the corners is acceptable. Open the door and adjust the threshold by turning the screw closest to the spot where light came through. Turn the screw counterclockwise with a Phillips screwdriver to raise the door threshold. Lay the edge of a framing square over the door threshold to see if it's straight and level. Adjust any other screws to the necessary height to make the top of the threshold level. Turn screws clockwise to lower a section of the threshold if necessary. Close the exterior door and check for light shining through from underneath after making the adjustment. Make further adjustments if necessary to close the crack under the entry door.
You can prevent water from coming under a door by using a door sweep or weather stripping to create a tight seal at the bottom of the door. Additionally, you can install a threshold or door dam to block water from seeping in.
its the frame on the door at the bottom which under the circumstances would block out smoke in the case of a fire :)
To fix a door threshold, you can start by removing the old threshold and cleaning the area. Then, measure and cut a new threshold to fit the door frame. Install the new threshold by screwing it into place and sealing any gaps with caulk. Finally, test the door to ensure it opens and closes smoothly.
To replace a door threshold, first remove the old threshold by unscrewing it from the door frame. Then, measure and cut the new threshold to fit the door opening. Install the new threshold by screwing it into place, making sure it is level and secure. Finally, seal any gaps with caulk to prevent drafts and water leaks.
It can be referred to as a door sill or door threshold. If you search images using either one of these, I'm sure you will find what your looking for. Hope this helps