Diy single wall stovepipe heat shield?

[DeeGore]

I'm wondering if it's considered ok to make my own out of a spare piece of single wall stove pipe.
I have a jog before the pipe goes thru the ceiling to avoid a hallway upstairs.
I want to reduce the 18" from the ceiling down to 12" for a little more head room.
I was thinking of opening the stove pipe, and using some ⅜" metal pipe cut at 1" for spacers, and screwing it on to the top side of the stove pipe.

 

[PASmoker]

I'm wondering if it's considered ok to make my own out of a spare piece of single wall stove pipe.
I have a jog before the pipe goes thru the ceiling to avoid a hallway upstairs.
I want to reduce the 18" from the ceiling down to 12" for a little more head room.
I was thinking of opening the stove pipe, and using some ⅜" metal pipe cut at 1" for spacers, and screwing it on to the top side of the stove pipe.

I didn't want to spend much on my garage's wood stove outside piping, instead of expensive insulated stainless I used steel single wall, wrapped it with fiberglass hi heat insulation(fairly cheap online) then wrapped it with aluminum trim coil that i had, riviting it together.

 

[DeeGore]

I couldn't find anything about using a heat shield on the stove pipe in the code books, but the National Fire Protection Association says a piece of 24 guage steel on the ceiling with a1 inch air space can reduce the 18" clearance required down to 9". I'm thinking I will go that route and keep about 13" of clearance.