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Quick And Easy Steps To Enclose The Area Above A Window AC

Quick And Easy Steps To Enclose The Area Above A Window AC

Dealing with gaps around a window air conditioning unit can be frustrating. While using plexiglass to seal the sides is one option, it may not always provide a perfect solution and can even reduce the efficiency of your HVAC system. So, what other methods can you employ to cover the space above your window AC unit?

Sealing The Gaps

Quick And Easy Steps To Enclose The Area Above A Window AC

Window AC units typically come with side panels to address the gap issue, but there are cases where the spaces above the unit remain uncovered. Here are some strategies you can employ to effectively seal the gaps:

Attach Weatherstripping
Weatherstripping is a cost-effective way to seal any gaps that could compromise the performance of your HVAC system. Clean the surface around your window where you plan to attach the weatherstripping, measure the length of the gaps, cut the adhesive foams accordingly, and position the seal with the sticky side against the bottom sash of your window. This will create an airtight seal.

Quick And Easy Steps To Enclose The Area Above A Window AC

Get Insulated Side Panels
Small window air conditioning units often come with accordion-style spacers that can help seal the gaps. You can use these spacers in conjunction with insulated panels to block air leaks. However, keep in mind that this is a temporary solution and not suitable for permanent installation. It may not withstand harsh weather conditions, particularly during winter.

Use Rope Caulk With Acrylic Glass
Rope caulk is a pliable clay-like material that can effectively seal narrow or hard-to-cover gaps. Measure the gaps, tear off a piece of rope caulk that fits into the space, and press it firmly into the gaps. Wipe away any excess caulk before turning on your AC.

Secure With Foam Insulation And Plywood
Plywood offers a more permanent solution for sealing the gaps above or beside your AC unit. It also provides an aesthetically pleasing option as you can paint the plywood to match your interior. Measure the gaps, mark the plywood accordingly, use a circular saw to cut the plywood, seal it with spray foam through the gaps, and let it dry. Trim off any excess spray foam.

Use Spray Foam Sealant
Spray foam sealants can effectively cover gaps in your AC unit. The foam expands and dries, creating a seal even in smaller gaps along the window. Keep in mind that it may be challenging to seal large gaps with spray foam as it comes out wet and requires drying time. Cover the surrounding area where you don’t want the foam to stray, follow safety precautions, spray the sealant along the edges, allow it to cure, build up dried sealants for larger gaps, and trim off any excess foam with an insulation knife.

After sealing the gaps, you may want to camouflage your window AC unit to blend it with your interior decor. Here are some ideas:

  • Use a folding screen: A folding screen is a convenient and low-maintenance way to conceal your AC unit while allowing airflow. Choose a design that matches your preferences.
  • Conceal behind curtains: Cafe curtains can be used to hide the AC unit when it’s not in use. Simply pull the curtains aside to allow airflow. The curtains will complement your interior without blocking out light and can enhance the room’s aesthetics throughout the year.
  • Decorate plastic sections with colorful tape: Apply double-sided tape with interesting designs to the plastic sections of your window unit, effectively camouflaging it and turning it into a unique design piece.
  • Build a cabinet around the window AC: Constructing a cabinet to cover your AC unit offers a more robust solution. Decorate the cabinet to match your room’s aesthetics, but ensure adequate airflow by incorporating ventilation openings or leaving space on the sides.

Improving The Insulation

Quick And Easy Steps To Enclose The Area Above A Window AC

To improve the insulation further, address other aspects of your home:

  • Upgrade windows and doors: Apart from sealing gaps around your AC unit, ensure that your windows and doors are energy efficient. Consider quadruple glazing your windows, installing low-emissivity glass, using low-conductivity spacer bars, insulating edges, sides, and sashes, and employing air-tight insulation and sealers.
  • Draught proofing: Draught-proofing is a ventilation solution that enhances energy consumption. It allows fresh air in during the summer and helps retain more than 25% of heat during winter. Look for signs of draughts such as light seeping through gaps, rattles, whistles, air drafts entering your home, or movement around curtains. Seal chimney draughts, exhaust fans, windows, and doors to address this issue.

Check If Your Window AC Fits The Window Opening

Lastly, ensure that your window AC unit fits the window opening correctly to avoid faulty sealing and compromised insulation. Measure the dimensions accurately to prevent any additional work.


Covering every gap around your window AC unit is vital to maintain a comfortable home and prevent moisture-related issues. Sealing the edges and gaps not only provides convenience but also ensures safety and energy efficiency.

Quick And Easy Steps To Enclose The Area Above A Window AC

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Written by HVAC Contributor

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