Utf8 in an Irssi/tmux/putty/windows Stack

Getting irssi running with utf8 support in a putty/tmux stack is madness. Here is what you have to do.

add lines in .{ba,z}shrc:

export LANG=en_US.utf8
export LC_ALL=en_US.utf8

add lines in .tmux.conf:

set-option -g default-terminal "rxvt"
set-window-option -g utf8 on

in irssi:

/set term_charset UTF-8
/set recode_autodetect_utf8 ON
/set recode_fallback UTF-8
/set recode ON
/set recode_out_default_charset UTF-8
/set recode_transliterate ON

in putty config:

window -> translation -> Received data assumed to be in which character set: UTF-8
                      -> Use Unicode line drawing code points