RAIN AND WATER
Keeping the the elements outside of the structure is critical to maintaining a suitable living environment. New Zealand has paid a huge price for not doing this well in the 1990's and 2000's. Water damage through a huge number of NZ homes has caused many issues.
Adopting the 4 D's is an excellent checklist for weather tight design:
Deflection – keeping the water away from any entry points.
Drainage – removing any water that does enter.
Drying – allowing any remaining moisture to be removed by ventilation or diffusion.
Durability – providing durable, low maintenance materials.