Purpose

• The main purpose of caulking around exterior openings, such as windows, is to help insulate your home from cold, heat and moisture. Building contractors usually make window holes in exterior walls larger than the size of the window for ease in installation. Improperly sealed gaps around the window frames can result in water damage to the wood molding. Although various types of caulking perform differently, all caulking eventually requires replacement. Removing and replacing cracked and brittle caulking from around the windows helps keep your home warm in winter and cool in summer.
  
  

Types of Caulking

• Caulking is a moldable, pliable sealant that dries to form a strong seal. Depending on the size of the cracks around your window opening, you may require a polyurethane foam caulking. This type of caulking works well when filling large gaps. The foam emerges from the applicator in liquid form, quickly expanding to fill the openings. Common caulks come in both paintable and nonpaintable formulas. Use a paintable caulk around wooden molding that you intend to paint, while using a clear, nonpaintable caulk around wooden molding that requires no paint. This clear caulking is less visible and lets the natural beauty of the wood show through.
  
  

Preparation

• Caulking won’t stick to damp or dusty surfaces. Clean the area to be caulked with a mild detergent, lightly scrubbing to remove any surface debris. Rinse away any soapy residue and let the wood dry completely before applying caulking.
  
  

Application

• Fill any large gaps beneath and between the window frame and the wooden moldings with polyurethane foam caulking. Wipe away any excess before it has a chance to dry. Fill smaller gaps and cracks that measure less than 1/2-inch wide with paintable or nonpaintable common caulking, using a caulking gun held at a 45-degree angle. Apply a thin, even stream of caulking into the crack, and then smooth it with a damp fingertip, using light pressure. Let the paintable caulk dry before painting the wooden molding.