How to Repair a Leaking Window Sill

How to Repair a Leaking Window Sill
Written By
Richard Toole
Richard Toole
Published: Jan 31, 2011
Updated: Nov 20, 2021
2 minute read

You can check the window for problems yourself before you call a builder or contractor to come out and examine the window. If you can find the problem, you can probably fix it yourself as well, which will save you money.

Things You Will Need

  • Caulking material (silicone)
  • Ladder
  • Utility knife/putty knife

Checking the Caulking

  1. Check the caulking on the outside of the window frame. If you see old, cracked, or rotten caulking, you will need to replace it with new watertight caulking material.

  2. Use a utility knife or putty knife to remove the old caulking. Slip the edge of your knife between the old caulking and the window frame. Pull upwards to eject the caulking from the joint. Pull the rest of the caulking out of the joint between the window frame and your house.

  3. Apply silicone caulking material to the entire joint around the outside of the window. Wipe away any moisture in and around the joint before using the caulk, moisture will prevent the caulk from setting properly.

Sealing the Window Sill and Jamb

  1. Check the where the window sill meets the jamb. The window sill and jamb (vertical frame pieces) should be sealed together. Open the window and see if there is sealant or caulk connecting the sill and jamb.

  2. Scrape away any debris or rotten sealant between the sill and the jamb with your utility knife. Wipe the area clean with a rag. The old material might have worn away, or you might not find any sealant or caulking at all.

  3. Squirt a layer of silicone caulking material in between the window sill and the jamb. Allow to dry before you slide the windows around.

The Drip Cap

  • A leaking window can cause severe damage to your home.
  • You may find find water pooling on your window sill, which is usually an indication of a leak somewhere above the window sill itself.
  • Use a utility knife or putty knife to remove the old caulking.
  • Pull the rest of the caulking out of the joint between the window frame and your house.
  • Squirt a layer of silicone caulking material in between the window sill and the jamb.

Photo Credits

Jupiterimages/Photos.com/Getty Images

Jupiterimages/Photos.com/Getty Images

Richard Toole

Richard Toole started writing for eHow in 2007 and enjoys writing about a fairly wide range of topics, including sports, hunting, health and fitness, music, and cooking. Toole first got into writing during college at the recommendation of…

Sponsored
HomeSteady Logo

HomeSteady is the ultimate guide for all your household needs, from cleaning and HVAC to electrical, DIY and maintenance.

Property of TechnologyAdvice. © 2026 TechnologyAdvice. All Rights Reserved

Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. TechnologyAdvice does not include all companies or all types of products available in the marketplace.