For the exterior, I would use urethane caulk(not to be confused with urethane foam). Mortar is not flexible and will quickly crack. 1/2 gap is doable, but will eat up some caulk.

Quote: Originally Posted by Gunguy45 You may have one problem that many folks don't realize. Many (most?) sliding doors are about 2-3 shorter than a regular entry door. Dang, I never realized that - good info

From memory I think the standard slider RO is 72 1/2 x 80 1/2 (or thereabouts)...most entry doors spec 82 1/2-83 ht..with 2 added to the nominal width (IE 36 nom = 38 RO). I could have that slightly reversed...been too long since I had to quote those off the top of my head...lol. I found out from the opposite problem. A condo/single family home builder back in VA did an entire development using double entry doors to the patio/deck...so after 8-10 yrs people were coming in to buy replacement patio doors...problem was they were too short and too narrow. And then there were companies that made sliders to standard double entry door height and width..which also complicated things. Easier to frame down..but still a complication. Off the shelf patio double......$299 (junk, yes..but just an example)...special order double entry equivalent...$650 or so...with a 2 week lead time. My rule since then has been...pull trim and find the R.O.....unless it's all new work.