Cut two 2 x 6 pieces of lumber and attach to the face of the wall running from the edge of your garage door jambs to the ceiling of your garage.
How to add height to garage door opening.
If you have an rv the door can go up to 10 feet.
Then to add two inches to the top of the door i used a piece of azek ripped to two inches and screwed it to the top of the top panel the garage door is white wood grain.
Standard single car garage door widths start at 8 feet for single car garages and move up in 12 inch increments to 10 feet wide.
Pull a measurement from the floor of your space to the ceiling next to the door opening.
For a garage attached or detached from your house of around 18 x 24 feet most popular width for a garage door is 16 feet.
I removed some siding and and re did the trim on the top of the door and then recovered every thing with aluminum and installed new rubber garage door sill around the opening.
Then the garage door would be 6 x 6 6.
For a shed the best size for installing a garage door is 8 x 14 feet.
2 a double door.
As for the height it is 7 or 8 feet.
Double car garage doors typically start at 12 feet wide and move.
This lumber will be used to attach your garage door track and a portion of your assembly.