DIY Network

How to Check and Seal Windows

Follow these steps and your windows will be airtight and ready for the season.

More in Windows Walls and Doors

remove as much of old caulk as possible
  • Time

    2 hours

  • Price Range

    $1 - $50

  • Difficulty

    Easy

Highlights:

Step 1: Check for Drafts

First, determine if any air is flowing through your closed windows. A great way to do this is to hold a lit candle close to the window seams. If the flame bends, then it could be signs of a draft.

Also check the caulk on the outside window frame. Exterior caulk can dry out in the heat of summer. If you find a whole lot of gaps and cracks, it's time to re-caulk.

check for drafts

Step 2: Remove Old Caulking if Necessary

Use caulk softener to help you remove the old caulking. It should be applied at least two hours in advance to give it a chance to work. Once the old caulking becomes soft enough, it should come up fairly easily with a putty knife or five-in-one tool. You must remove as much of the old caulk as possible to ensure that the new caulking will adhere properly and give the window a good seal.

Step 3: Apply New Caulking As Needed

Polyurethane caulk works for both small and large gaps, so one tube should take care of a whole window. To begin, cut the tip off of the tube of caulk at a 45-degree angle so that the tip will fit nicely into the window seam, and load it into a caulking gun.

Clean the surface as best as you can and make sure there are no traces of old caulking still left. Push the caulk along the seam in a smooth motion (Image 1). When filling larger gaps, move more slowly to let the caulk adequately fill the space. Finally, use a wet finger to smooth out the caulk and give it a clean, finished look (Image 2).

Give the caulking 12-15 hours to dry and set, and your windows should be airtight for the season.

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