Pressure on a patio door lets say the area is 2m x 1m = 2m squared
Atmospheric pressure is 100000pascals (same as 1 bar, 14.5psi)
And pressure = force/area
so force = pressure x area
So force = 100000(pa) x 2m^2
Force = 20,000kg
or 20 tonnes pressing on the glass (evenly distributed)...