14" mirror for project--newbie question

I am looking to purchase a finished mirror for a truss dob I am designing. The mirror is a 14" plate glass and has a thickness of 1.1". This thickness seems to be a lot thinner than most vendors I have seen advertising a 14" mirror. The cost of the mirror seems to be very good (recognize you don't get anything for free!). I am concerned however since the usual thickness for a 14" mirror is closer to 2 or 2.5" What problems will I face by purchasing a mirror that is 14" but only 1.1" thick. The mirror will be a paraboloid design.