Hi, I made the mistake of having my 2.2 metre observatory erected on decking instead of concrete. The decking was down two years before the Obsey was installed a year ago. So far I have had no problems with dampness or condensation, but after reading the postings, eventually rot must come. I will then have to have the observatory lifted in one piece placed on the lawn at the side and a proper concrete base installed,and the observatory placed on the new base. The observatory is heavier duty than a Pulsar so will be heavier to lift,but will deal with that when the time comes. The cheapest is the always the most expensive in the end
Dave