Is the phrase "out back" a prepositional phrase?

[rezaaa]

I noticed the phrase in a grammar lesson on prepositional phrases, and it was part of the another adverbial prepositional phrase. The sentence read : "we keep the lawnmower in the shed out back." . I don't think "out" can function as a preposition.

 

[5jj]

I don't think "out" can function as a preposition.

Out is a preposition in:

He ran out the door
She looked out the window.

 

[rezaaa]

I have always thought "out of" is the correct prepositional phrase.

 

[Tdol]

Out of back would not work- we use out back for that part of the garden.