If this is the case it is recommended to put the molding up around your sliding glass door piece by piece.
How to trim out a sliding door.
Use paintable silicone caulk around the exterior door casing.
In either case once you re ready to begin choose a side of the door to begin with and start lining the molding up in the exact spots you measured and marked earlier.
Mark with a pencil.
Finally mark the reveal on the jambs to show where the edge of the trim goes.
The door is standard height and there is 1 of spray foam between the door and block at least on the sides.
Measure each side of the opening around the edge of the sliding doors and add the width of the trim to each measurement.
The project will take a little longer the first time you do it but you ll be trimming out doors like a pro in no time.
The first step in any trim job is to prepare the jambs for trim.
1 remove the baseboard where the door trim will be.
Then scrape or sand the face of the jamb to smooth out any paint or finish that s built up.
Score the top of the door with a utility knife.
Cover the foam insulation with trim and add a small amount of caulk to the visible joint between the trim and interior wall area.
I measured out the width of the 1 6 and the 1 2 and used my handy multitool for cutting a straight line through the baseboard.
Step 3 install.
It should have wood in there flush with the door frame inside and out.
Secure the first piece with your carpentry nails.
Take measurements for the top of the opening and the sides.
Step 4 cut three pieces of wood trim equal to the measurements you found in step 3 using a handsaw.
Then nail the interior and exterior trim to the wood.
If you re replacing trim pry it off and remove the nails from the jamb.
Use expanding foam insulation to seal any gaps between the door frame and wall.
Like steve said get rid of whatever that is above the door and frame it in.
Use a putty knife to remove the excess after it dries.
Here are the steps i took for the sliding door trim.
Honestly when i bought this i thought it was going to be a one time use tool but i am continually amazed at.