Yep, proper roof really well insulated which means it is classed as another room proper so as you say ups the value of the house. But the main benefit is not freezing in the winter or like a crematorium oven in the summer. We even had to have a proper on the wall air conditioner fitted and still it was not really comfortable, plus it cost a fortune to run. Now the room is so good we had the air conditioner taken out and it is cosey in the winter and more than bearable in the summer.
Conservatories seem a good idea at the time, but living with one is a completely differetn kettle of fish.
