- Dr. h.c Mario Schmidt, Managing Director, Lingel Windows and Doors TechnologiesWhat is the importance of Window Sills?Window sills are integral part of the building structure. The building envelope is outside part, and has to face diverse weather conditions or the fury of nature. We protect the outer skin by having different kinds of claddings.  For example, stone cladding, marble cladding and in some areas, we fix tiles, wooden cladding or special plastering, so that the outer structure looks presentable and is protected against diverse weather conditions.But in India, the window sill area is completed neglected. The outer walls by default are vertical. So when the rain water hits the wall it will flow down. But in the window sill area, the windows are fitted in the centre and have a 2 to 4 inch of a horizontal plain area.So eventually in this area, the rain water and dust may also get collected. If a mason does not make the slope towards the outer wall, the water will be collected towards the window. In monsoon, there are chances of water leakage and the water may enter the house.What are the options to consider?Option 1:You can have a stone cladding at the sill area but even then, it should be taken care of as  there is one inch of overlap, so that the water flowing out from the window sill is actually going down and not hitting back to the outer surface of the wall.Option 2:This is widely used in Europe where the window sills are made out of Aluminium. You can choose the colour  to match it with the colour of the window. You can opt for lighter shades to darker shades to match the outer walls.The rain water hitting the glasses will drain down on the window sill and as the window sill will have a slope angel of 5° to 8° so that the water will completely drain out and if the window sill is around 50 mm in front of the building then the rain water will drop down hitting the surface of the building. This will ensure there is complete water tightness so in the monsoon when the water comes through the glass it will immediately drain out. At the sides where the Aluminium sill is attached to the wall, end caps are connected. This will assure complete water tightness and it provides the perfect connection to the wall.