What kind of roof structure in a hundred year old house

Hi I would expect you to find a traditional roof construction with rafters running from the edge of the house (Wall plate) up to the ridge board, there will also be one or two purlins (large timbers running horizontal across the roof) these will be supporting the rafters in the middle to help avoid the roof bowing under the weight of the tiles, slates or other covering. There may be a large rafter called a kingpin that is used as a central brace to support the purlins. you may also have some tie beams bracing the rafters from spreading. There will be joists that are supporting the celings which unless thay have been changed will be of a lath and plaster construction with a couple of supports going horizontal to there to help support them. It is similar to a modern roof and as for asbestos there is no way of knowing, it may be worth asking your neighbour if they have a loft hatch to see how their roof is constructed. Also be careful of any woodworm and or rot from damp as this would weaken the structure if you are getting in there, the timbers are going to be fixed together with cut nails which degrade over time so make sure you use a board to span several joists at once to spread your weight. In older style houses very often loft accesss is gained through the cupboard above the stairs ceiling and this would be an ideal place to gain entry as you would no risk damaging a complete ceiling. Hope this helps Stronghold