Window Sill Caps: Covers, Ideas, and Protection Options

Window caps, in this context, refer to protective profiles designed to cover and seal the joints around windows, including sills and lintels. WEATHERCAP® window caps are made of soft, flexible lead that works with sealant to create a durable, weather-resistant barrier. They prevent sealant failure and protect the underlying masonry from moisture damage and deterioration.

Our soft lead caps are installed over the sealant in the joint. This shields the sealant from direct exposure to UV rays, rain, and temperature fluctuations, which are primary causes of degradation. The cap's flexibility also helps absorb stress from building movement, preventing the sealant from tearing or pulling away from the masonry (margin checking).

Absolutely. WEATHERCAP® is ideal for historic restoration and is specified in the U.S. General Services Administration (GSA) Historic Preservation Technical Procedures. The lead material oxidizes to a neutral grey that blends with historic masonry, and its flexibility is crucial for protecting older structures that experience natural settlement and movement over time.

Our products are made from a soft lead composition. This material is chosen for its unique properties: it is highly flexible, durable, and resistant to corrosion and mold. Its low elastic modulus allows it to 'creep' and adjust to building movements without failing, providing a permanent, elastic seal that protects the underlying sealant and masonry joint.

Yes, all WEATHERCAP® products can be painted to match the surrounding architectural elements. While the soft lead naturally oxidizes to a neutral grey that blends well with most stone and masonry, painting provides additional aesthetic flexibility for architects and builders to meet specific design requirements for both new construction and historic restoration projects.

All our stock and application-specific window sill caps are supplied in standard 6-foot lengths. This allows for easy transportation and handling on the job site. The 6-foot sections can be easily cut to size and fitted to the specific dimensions of the window sills, lintels, or other masonry joints requiring protection, ensuring a clean and precise installation.