Behind the house-to-ceiling height and area are not included as a floor, not in any way we can achieve an impact on the strength of the structure. It is important to do well and for reinforcing the strength of the roofGENAI waterproof and to prevent leaks.KE make a prepayment by removing the top floor ceiling and the floor is part of the floor can be relatively easy to be very large windows. Can be used as a catch-all without regard to volume ratio. However, to establish a skylight on the roof of the existing, I want to check in detail in advance.