Door And Window Cill Projections

What Does An Aluminium Door and Window Cill Projection Need To Be?

When purchasing aluminium doors and windows it may be a requirement to have a cill to the base of your aluminium doors and windows. The reason for this is for aesthetics and drainage.
The type of aluminium door and window cill is generally determined by the construction of the building. Through our knowledge and experience of what is required we have produced this guide to be of help and assistance to you.

What is the minimum aluminium door and window cill projection?

There are differences of opinion within the door and window industry as to the right answer to this question. The answer is that there is not an absolute minimum aluminium door and window cill projection. Considerations do however have to be made for the building construction and the materials used.

The diagram below shows the Reveal Doors and Windows recommended minimum aluminium door and window cill projection. At 45mm the distance is sufficient to allow water to drain away from the brickwork and on to the ground. If the water was to be allowed to drain on to the surface of the brickwork it can cause undesirable staining. Prolonged exposure to water can cause damage to the bricks themselves allowing this to enter into the interior of the building.

What is the maximum aluminium door and window cill projection?

Unlike minimum aluminium door and window cill projections there is no real consensus on the maximum aluminium door and window cill projection. From an aesthetic perspective it would be unsightly to have a very deep cill projection at high levels.
If you consider the projection from a safety perspective Reveal Doors and Windows recommendation would be between 75 and 100mm from the front face of the brick. The reason being is that if the projection is too far passers-by could come in to contact with the cill corners and hurt themselves.

At 75 to 100mm the aluminium door and window cill projection is more than enough to drain any excess water away from the building. This is not a safety concern at ground floor level.

To Summarise

Aluminium door and window cill projections are one aspect to consider from a drainage perspective but also an aesthetic one. A beautifully designed and manufactured aluminium door or window will be the focal point enhanced by the cill.
Cills or more specifically drainage via aluminium door and window cills should be designed to protect your property. There are thankfully different depths of cill that can help achieve a balance of protection, safety and aesthetics.
For additional information please call Reveal Doors and Windows on 0113 386 9207. We are always happy to help you and discuss your specific requirements in further detail.