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Window Caulking Problems

How Often Should I Check the Window Caulking?

Newly installed windows are usually caulked on each side of the flashing, ensuring that no moisture or air seeps through. The windows are also caulked again around the exterior perimeter of the window, which keeps water and insects out of the sill. Over time, the caulk will deteriorate and the seal will fail, though a good installation should last without hassle or maintenance for years. Still, it’s a good idea to check the caulking on the windows every two to three years during your spring and/or fall clean-up. It is only recommended that the inside of the window be caulked in cases of extreme draftiness, which usually comes from a poor installation, lower-quality windows or shrinkage/warping of wood due to age.

How Do I Know Where the Caulking Failed?

To identify where the caulking has failed is easy. Take a look at the exterior of the window and find the bead of caulk that runs along the edge (usually spongy to the touch). If the caulk is worn or failing, cracks will appear or it will be hard and brittle rather than pliable. Be careful not to damage good caulk by prying too heavily; generally, fingers will work as well as any tool. Check all the sides and make a note of the windows that need repair. If you’re not comfortable working on your own house, or if you live in a condo/HOA, it would be wise to call CalFinder and find a pre-screened contractor that can ensure the job is done right. You can get window estimates right here!

Fixing the Window Caulking

To fix the caulking on your windows, you will need a wire brush or some other heavily abrasive material to remove all the old caulk, paint, debris and mortar. You will also need a caulk gun, caulk and some water with a wet rag for cleanup. The most difficult decision to make is the type of caulking that needs to be applied. For exterior window applications, it’s best to go with a higher quality caulk from DAP or other similar company. Also, consult your window manufacturer’s recommendations when choosing caulk to prevent voiding warranties. Silicon caulk is the best, but it can’t be painted over. Caulk usually comes pre-tinted to match the common colors that surround windows. If you must paint, use an acrylic/silicon blend. Latex caulk also works well for painting.

  1. Cut the tube of caulk to the diameter of the average size of the gap around the window (the hole in the handle of a caulk gun is designed for this).
  2. If the gap is larger than 1/4”, a foam backing material is needed. Find this at the local hardware store.
  3. Apply the caulk.
  4. Smooth and compact with wet finger.

It is sometimes recommended that the bottom of the window be done first with the two vertical sides, then overlapping the bottom bead of caulk. Let the caulk cure for 24 hours to paint.

What if the Problem is a Failed Seal?

If that doesn’t solve the draft problem, the window may have failed seals elsewhere. Refer to our article about window seals in this section. If that still doesn’t help, a second round of caulking may be in order. To caulk the interior, pry off the trim and expose the frame. If you are saving the trim, be very careful not to damage it. Fill any gaps with insulation or foam backing material and then seal the interior edge of the window just like you did for the outside. Replace the trim. While interior caulking is not usually recommended, it will rarely do any harm and is not hard to remove during uninstalls.

IMPORTANT: No matter what you do, if your windows are under warranty, make sure you follow all their guidelines. Or, call us and we’ll have a contractor out to you who can make sure your warranty stays valid for years to come.

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