Plastic and stone window sills offer many similar benefits for the home-owner when compared against wood; both materials are durable, weather resistant, retain colour, and easy to maintain. There are important differences to be aware of as well. Cost is one obvious difference, below will present some other important aspects of both materials to consider.
Durability: life expectancy
The life expectancy of plastic windows sills ranges from 15-30 years. Stone by contrast implies permanence. In the comparison of materials stone will last longer and maintain its appearance. The long term weathering of plastic that eventually leads to cracking, warping, or discolouration is not an issue for stone products. Both materials require some attention to prevent mould in moist climates, but the weathering that eventually damages plastic window sills will lend a patina of antiquity to stone.
As a material, plastic is generally not as strong as wood or stone. The potential uses for the interior and exterior portion of the sill will be are expanded when a stronger material, such as stone, is used that can bear more weight.
Planning for reuse and recycling is a growing consideration for many construction projects, especially those seeking LEED certification. Stone is a material that can be reused or re-purposed with minimal processing. Plastic window sills, particularly those made from PVC (poly vinyl chloride), are not easily reused and infrequently recycled.
Design Flexibility and Aesthetics:
The primary benefit of plastic windows sills is that it is an inexpensive, practical, and convenient material; its practicality can be a challenge for projects that require design flexibility or which aspire to a more refined aesthetic. Plastic sills are generally pre-fabricated and customizing details beyond the standard variations offered by a given manufacturer will be difficult. A stone windows sill can be decorated and detailed to custom specifications for individual projects or individual windows. Additionally, for restoration work, brick, wood, or stone sills may be required to maintain the historic character of the building.