Hi Blue, the only thing I can think of is the animal was trying to find a way to the chook houses and thought up and over might be worth a try. There were also a few fresh rat droppings in the roof and I imagine a nest of tender pinkies or some baby rats would go down a treat for a hungry skink so maybe he decided to stay a while. There could also be some raids to the hen houses and fruit trees going on, we live in a joined duplex and the roof would be ideal spot to access both yards. My dogs are indoors mostly and only small so who knows? There are no plants or bushes up the house BTW. They just seem to go nuts at this time of year, rarely seen otherwise. Maybe males with the sap rising! Very interesting animals, they are one of the few reptiles that seem to live in family groups. There used to be PVC pipes set in the kerbing that went underground about 15 meters down to the bush/river, for road drainage. There would often be one large skink basking its head on the road, with another smaller animal tucked up next to it in the pipe. Sadly the road was upgraded and those huge open style drains with 15cm high and 1M wide opening at the kerb installed. I think they must be a disaster for wildlife, the kerb funnels them along untill they fall into the drain, they have a very deep concrete sleve with a sump around 45cm deeper than the outlet pipe, so essentially a death trap for most.
Also forgot to add it is an old house, the insulations -several types over the years, are evrywhere. Some lazy b@5+@# "installed" foil backed insulation by draping it evrywhere over all the beams, so lots of lovely snuggly places to hide for many creatures.