Answers

1. It was cheaper. This building was built in a period when money was short and architects had to cut the cost. The trouble is that flat roofs have a life of about fifteen years. After that they tend to leak and many have had to be replaced, with pitched roofs, new asphalt, or other means. A headmaster once said, “Show me a flat roof and I will show you a bucket”.
    
2. Asphalt or tarred felt. When money was particularly tight soon after the Second World War, some flats in the Thames Estuary were covered with sheets of polythene. Seagulls pecked through them in weeks.
    
3. The drainpipes are at the back of the building because the architect wanted to keep his elevation clear and not cluttered up with drain pipes. Also, his drainage pipes may have been at the back of the houses and not under the road.
    
4. Wooden casements, hinged on the uprights to open outwards.