Doors – Installing a sliding patio door…why does the entire frame have to be square, level and plumb


It has been raining cats and dogs for two days (fall wet season). I am looking at my newly installed but but not sealed patio door that is not screwed, not plumb-ed and not leveled and I am trying to understand why you need the entire door to be level plumb and square.

From what I understand the fixed door does not care much unless there is too much tension or pressure on it which could make it crack in time

The sliding door is more sensitive to level and plumb and square issues since:

-if will not close (if it is not parallel with the vertical side that it rests against, when closed)
-it will wear and tear the track if the track is not level

The door gets shims and it has around 1/4" space all around excepting the bottom side. The shims are used to fix it in position and to make it square and plumb but there is little tension that is transmitted from the structure to the door from the adjacent walls.

So my question is, why do you have to be so careful to make the entire frame square and plumb/level on all the edges ?

Edit: here is an example, exaggerated for the sake of argument
enter image description here

Best Answer

Out of square doors/door frames either do not close (if really bad) or seal properly; a 1/4" can create a significant gap in between the door and weather stripping allowing significant heat/AC loss.

Out of plumb doors either open or close from gravity which is simply annoying.