Hi Nik,
I have a 2.7m Pulsar dome, that sits on top of a wooden building.
I found I got heavy dew on the dome and more worryingly, surface water on the metal work of the paramount gem. I also keep a desktop in a large plastic box. I keep the PC powered on and have installed a small DE-humidifier that runs 24/7 during the damp season.
I have had no problems during the past four years.
Eric