When we talk about a window it would be the word used to describe a structure that has a head, two jambs and a sill basically. It may be divided horizontally and for this a transom may be used; for a vertical division, a mullion is used. The area of glass used in a window is called the light and the opening of this is called the casement (if it is hinged) and the sash (if it is sliding). A sill to the window would be the lower edge of this structure, which may be made of steel, aluminum or timber, but since the matter here pertains to a rotted window sill, it is obvious that the window sill affected by it is made of wood.

Signs of rot in window sills:
According to the American Society of Home Inspectors, there are many tell tale signs of damage to window sills, among which the commonest are those signifying deterioration due to rot. This may be manifested in various forms like the wooden window sill getting stained or the wood becoming soft. The main point of concern here would be if this damage is caused due to the noticeable presence of black or yellow fungus or insects, or in some cases, both these elements.
If the window sill in question is made of wood that has been painted then a soft indentation or depression under the surface of the paint may be hinting at the rot that has set in.

To ascertain the extent of rotting of the window sill, one could probe the spot with an ice pick or screwdriver and determine whether the wood is soft or spongy. If the beam of the window sill shows more than 15per cent damage, then serious structural repair may be required, if not replacement. A pressure-treated replacement will prevent this problem from occurring again but thanks to the invention and successful use of handy epoxy patches that are easily available in the market, this 'rotten' problem of window sills have a quicker and more economical fix for home owners in the present day. Most repair kits contain a consolidator that hardens any wood and a two-part epoxy; which, when properly mixed and used with the appropriate fillers, prove to be stronger than the original wood.

Interior Window Sill
An interior window sill is that portion of the window ledge that stretches or protrudes into the interior of the room. The window ledge is horizontal and the interior window sill, which is horizontal and is next to the window sash when the window is...

Replacing Window Sill Panels
A portion of the window ledge that stretches into the interior or the exterior of a room is known as a window sill. Also referred to as a window stool, window sills are horizontal and can vary in size and width. Wood, PVC, stone such, as slate,...

Window sill trim
It can be a do-it-yourself project, provided one has basic carpentry skills and the right tools. The stool-and-apron design with mitered casing is simple and practical so, beginning with a miter saw and leading up to more is recommended. To make the...