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How to Insulate Windows for Summer

Insulating your windows can keep your air conditioning bill from making you sweat. Drafty windows or simply the sun blazing through a big pane of glass can raise indoor temperatures significantly. You have multiple options for sealing out heat or blocking burning rays on the windows in your Delaware Valley home. Your approach when learning to how to insulate windows for summer will depend on the immediate need for relief and your budget.

How to Insulate Windows for Summer Step by Step


  1. For drafty, rattling, or warped old windows, insulating for summer requires weatherstripping.
  2. Select an adhesive weatherstripping product for vinyl or metal windows.
  3. A nail-on weatherstripping may be appropriate for old wood windows but adhesive products remain an option.
  4. Clean the channels where the sashes move in the window jamb.
  5. With a putty knife or utility knife, scrape off old weatherstripping and chipped paint if it is present.
  6. Measure and cut the weatherstripping to fit the channels.
  7. Stick or nail the weatherstripping in the channels.
  8. Measure the width of the window sashes.
  9. Cut weatherstripping to size.
  10. Attach weatherstripping along top and bottom sashes.

Window Treatments

  1. Blinds, shutters, or thermal curtains can block hot sun and are great choices when you already have tightly sealed windows.
  2. Measure your windows and buy appropriately sized window treatments.
  3. Buy window treatment hardware.
  4. Drill holes for hardware screws.
  5. Attach hardware and hang window treatments.

Bubble Wrap

  1. Large-cell clear plastic bubble wrap provides an effective heat barrier.
  2. Measure your windows and buy enough bubble wrap to cover the space.
    1. You may reuse old bubble wrap collected from shipping packages.
  3. Fill a spray bottle with water.
  4. Spray water on the window pane to create a film of water across the surface.
  5. Starting at the top, press the bubble wrap with bubble side toward the glass against the wet surface.

Reflective Window Film

  1. A reflective film that halts the heat-generating rays of the sun works well on otherwise well-sealed windows.
  2. Purchase a reflective window film product.
  3. Wash and dry the window panes completely.
  4. Measure window panes.
  5. Cut film with a utility knife to size.
  6. Spray a sheen of water across window pane on the inside.
  7. Press film over interior wet glass.
  8. Smooth the film carefully with a squeegee.

Draft Snake

  1. A draft snake is a stuffed fabric tube used to block drafty edges around doors and windows.
  2. Buy or make a draft snake to fit the window that needs insulation.
  3. If making a draft snake, choose a fabric with a color that matches the window if possible.
  4. Cut a 6-inch wide piece of fabric long enough to cover the drafty edge.
  5. Fold the fabric lengthwise and sew a long seam along the edge and one end.
  6. Turn the tube inside out so that seam edges are on the inside.
  7. Stuff tube with insulating material.
  8. Hand sew the open end to close the tube.
  9. Place a tube along the window sill and another on top of the bottom sash.

Tools & Materials

  • Measuring tape
  • Utility knife
  • Putty knife
  • Spray bottle
  • Plastic squeegee
  • Hammer
  • Sponge and soapy water
  • Power drill

Upgrade to New Energy Efficient Windows

Although learning how to insulate windows for summer can reduce heat penetration, new replacement windows offer the best solution. Energy-efficient windows come in many styles. They feature weather-tight construction, double panes, and UV ray blocking finishes applied at the factory. PJ Fitzpatrick has replaced thousands of windows throughout the Delaware Valley. We guarantee the quality of our professional window installation services. Contact us today for a window replacement estimate.

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