Is it a modern city house? I Like all the neon signs in the background #:-)
The panelled roof is a little unrealistic ....... have you a certain reference? Not many roofs look like this.
Nice stiff cardboard makes lovely slates. Cut in squares and overlap them by 50% of the next row like brickwork, so they are half the size. Slodders idea with the business cards is excellent.. thats what you are looking for ... even a cornflakes box. Build up both sides and then for the peak, fold the squares in half and starting at one end, slide on top, then overlap the slighly as a ridge tile on top. Or get a McDonalds straw ... half it long ways along the stripe, cut into similar lengths and use these as your ridge tile.
see these roof tiles to understand what I mean These straws are excellent as they can be used for mediterainain pipe tiles as well!
Check out Adam Avukich (?) thread where he built his houses with cork. If I could find cork thats what I would use for brick work