Can depend on how the roof is constructed. Generally need to have good air circulation to keep it dry. This may have been accomplished with vents at eves and ridge so insulation board in rafters will just have outside air under them.
Interesting to hear the comments about X10, I've just read about it occasionally for past 15 years or so but never used it. Have talked in the past to some computer guys who control all sorts of things with it seemingly without problems.
Something like "Switch, Pushbutton, DPDT, Momentary, Gold PC Terminals" RS Stock No. 2508397018 ? On the Welcome to rswww.com site. They may well have others.
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