Damaged Window Sills
Damaged window sills, on wood construction windows, are one of the more common repairs we are contacted about. Because window sills present a somewhat flat profile and have multiple joints where the brick molding and sash tracks terminate, they are susceptible to decay. Damaged window sills, that remain unrepaired, can lead to other more extensive damage to the structure, including decay of the exterior siding, wall framing, hardwood flooring, sub-flooring, floor framing, as well as stained and moldy drywall. Ants and termites may also be attracted to, and subsequently infest areas that are persistently damp.
Window sills with only minor damaged may be repaired by replacing just the sill nosing or by removing the damaged area of wood and using a filler, such as bondo body filler, to repair the damaged area. Review the post “Woodpecker Damage Repair” for detailed instructions on how to make a repair using body filler and view the slide show “Chimney and Window Sill Repair Project” to see a window sill repair project utilizing body filler.
Severely damaged window sills render the entire window unit unfit for use. Proper repairs are achieved by removing the interior window trim and then the window unit, including the exterior trim or brick molding. Any damaged siding should be removed at this time. If the wall framing under the window shows signs of damage, additional siding as well as drywall from the interior, may have to be removed to facilitate repairs to the framing. Once any needed framing repairs are completed and the rough opening is properly flashed, a new window unit can be installed. The exterior repairs are then completed by installing any required siding, then caulking and painting the window and surrounding siding. Interior repairs are completed by replacing any insulation and drywall that were removed and installing the window trim.
Some window manufacturers have begun to use composite window sills and sill nosing along with vinyl brick molding which greatly increases the weather resistance of windows utilizing those components. WHMS encourages the use of windows featuring these weather resistant components whenever feasible.
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