The height of the rough opening must be 1 5 inches taller than the garage door you intend to buy.
Making garage door opening taller.
Easy to do and it can solve alot of problems.
This means building a wall that spans the entire distance of the opening and is strong enough not to move until you are done.
Usually 4 or 8 feet.
That made my door height two inches taller.
If you are lucky it s in good shape and either made from 2x12 s or even better a glulam beam.
If you have the room on the back side of your garage you can make your garage into what is called a jack jill garage.
That is the side where your truck is to go you can build out on the back side.
Before removing the header you will have to support the roof above it.
To put it into perspective if the garage door is let s say 8ft tall make the height of your opening 8ft 1 5 inches tall.