atw: Extra spacing after full stop

Can anyone provide a yes/no answer to the question of whether extra
spacing between sentences should/shouldn't be used in
Manual/Guideline/Standard type documentation? I find many professionals
use two spaces after each full stop and as a Technical Writer this
bothers me. After researching it (Chicago Manual of Style and various
Google pages) I have found that it is not correct practice.

Chicago Manual of Style:
"2.12 Line spacing and word spacing 
For the hard copy, the entire text and, if possible, all extracts,
notes, bibliography, index, and other material should be vertically
double-spaced. A single character space, not two spaces, should be left
after periods at the ends of sentences (both in manuscript and in final,
published form) and after colons."

I am writing up a Formatting Guide for my company and I would like to
state that extra spacing should not be used as common practice but I
would just like any other opinions/facts on this please.
Thanks.

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