All depends on the cost of materials as brick vanity in price

Yes you can prop up the roof using acrow props and 8x2 planks to hold up the roof,the original timber of the roof should be anchored to house wall so shouldn't move,once you prop the roof up there will be no problems taking the uPVC away to start your brickwork.you can build on the existing base if it's thick enough,but never tooth the brickwork to the existing house..

Hi if it’s a tiled roof then trying to prop it up while you work underneath it would be quite dangerous also you would want a cavity wall to stop damp transfer so would really recommend ripping everything out and starting again

Would depend on size of existing base would need to do a test dig to establish first then the type of door wanted and how many windows if any..

Lots of factors involved but brick costs come into it

是的,这是可能的屋顶,砖work and a new door installed underneath providing it is not larger than the roof.