sealing windows

Leaking windows are a common household issue that can lead to a multitude of problems, from water damage to energy inefficiency. Fortunately, with the right tools, materials, and techniques, repairing leaking windows can be a straightforward DIY project. This article will guide you through the process of fixing leaking windows, emphasizing the importance of using paintable silicone caulk and addressing extreme cases where rot has occurred.

Assess the Damage

Before diving into repairs, it’s crucial to thoroughly assess the condition of your windows. Look for signs of water damage, including peeling paint, rot, or mold. Identifying the extent of the damage will help you determine the appropriate repairs required.

Gather the Necessary Tools and Materials

To effectively repair leaking windows, you’ll need the following tools and materials:

  • Paintable Silicone
  • Caulk gun
  • Utility knife
  • Putty knife
  • Sandpaper
  • Exterior colour-matched paint (with primer mixed in)
  • Safety goggles and gloves

Seal the Window Edges with Paintable Silicone Caulk

One of the key steps in fixing leaking windows is applying paintable silicone caulk around all edges of the window. The caulk should be applied to the joints where the window frame meets the wall, both inside and outside. The exception here is the window base, which should be left unsealed to allow for proper ventilation and moisture escape if it enters the frame.

Here’s how to apply silicone caulk effectively:

  • Clean the area to be caulked to remove dirt and old caulk.
  • Cut the caulk tube nozzle at a 45-degree angle, leaving a small opening.
  • Load the caulk into a caulk gun.
  • Squeeze a steady bead of caulk along the window edges, ensuring a consistent seal.
  • Use a putty knife or a wet finger to smooth the caulk and create a neat finish.
  • Let the caulk dry according to the manufacturer’s instructions.

Repairing Extreme Cases of Rot

In cases where rot has taken hold, it’s essential to address this issue before sealing the window edges. To repair rot, follow these steps:

  • Remove the rotted wood using a utility knife or chisel, in some cases, you may need to remove large sections of rotten timbers.
  • Apply an appropriate wood filler, builders bog is a common choice.
  • Allow the filler to dry, and sand it until it’s smooth and level with the surrounding surface

Check out our article on Common Causes of Mould Growth in Silicone Sealants and How to Prevent It & Caulking and Signage: A Perfect Match for a Polished Finish.

Caulk the Glass

If your windows are prone to water infiltration and you want to provide extra protection, you can also caulk the glass. This step should be considered after sealing the window edges and addressing any rot issues. Follow these steps:

  • Apply a thin, even bead of paintable silicone caulk along the perimeter where the glass meets the window frame.
  • Smooth the caulk with a putty knife or a wet finger.
  • Allow the caulk to dry as per the manufacturer’s instructions.

Prime and Paint

After completing the necessary repairs and caulking, it’s essential to prime and paint the window to provide an extra layer of protection and a polished finish. Primer will help to seal the surface and create an even base for the paint. Finish with a quality exterior paint to ensure the window is well-protected against the elements.


Repairing leaking windows is a manageable task when approached with the right tools and techniques. Using paintable silicone caulk to seal the window edges is essential, as it not only prevents leaks but also allows for proper ventilation. For more severe cases involving rot, proper repairs and additional caulk around the glass can be considered. By following these steps, you can enjoy windows that are both functional and aesthetically pleasing, while protecting your home from water damage and energy loss.