How do you insulate windows with cardboard?

Author: Onie Mayer V  |  Last update: Wednesday, June 17, 2026

A quick and easy way to insulate your window is by opening it, placing the cardboard on the windowsill below, and shutting the window onto it. With this method, you can stop cold air from seeping into your home from underneath the window, but it won't insulate any cracks along the sides of your window.

Does cardboard on windows keep cold out?

8 Answers 8 First of all cardboard is not a good reflective insulator. Second, hanging cardboard on the inside will not help much since the heat has already entered the room through the glass. Get some aluminum cooking foil that will reflect the heat and attach it to the window from outside.

Is cardboard a good window insulator?

I find cardboard an excellent insulator for windows. You can even cut a small door in it to look out! It blocks out all the sunlight so be prepared for a dark room. The kit you listed only blocks air drafts. A tight fitting cardboard will do both air and heat.

How to blackout windows with cardboard?

For a very inexpensive solution just cut cardboard squares to fit in the windows so no light can creep in around the edges. Then close shutters. In the morning remove the cardboard and store in the closet.

What is the best thing to insulate windows with?

Plastic and blankets are indeed two of the best cheap & fast methods to improve window insulation. Another thing in this vein is sticking bubblewrap sheets to the glass.

How to Insulate Windows | Cheap and Easy with Plastic Film

How to block out heat from windows?

10 ways to insulate windows for summer
  1. Add weatherstripping to your windows. ...
  2. Use window films to reflect heat. ...
  3. Invest in cellular shades. ...
  4. Purchase blackout blinds. ...
  5. Use draft snakes for window insulation. ...
  6. Insulate windows using bubble wrap. ...
  7. Upgrade to energy-efficient windows. ...
  8. Install insulating shutters.

How do I stop cold air from coming through my windows?

10 Ways to Keep Cold Air From Coming Through Windows
  1. Install Magic's Thermal Blinds. ...
  2. Replace Weatherstripping and Caulking. ...
  3. Replace Worn Out Hardware or Locks. ...
  4. Apply Window Insulation Film. ...
  5. Hang Thermal Insulated Curtains. ...
  6. Use Door Snakes. ...
  7. Install Secondary Glazing. ...
  8. Upgrade to Double Pane Windows.

Can you put cardboard over windows?

How to insulate your window with a cardboard box effectively. Windows can be a significant source of heat loss in homes, especially during colder months (or heat gain in hot climates). Insulating your windows with a cardboard box is a cost-effective and eco-friendly solution to help retain heat and reduce energy bills.

Do black garbage bags work as blackout curtains?

Black trash / Garbage bags

They don't make for the most beautiful drapery, but they sure can darken your room effectively. You can install the trash bags only with water like with the tinfoil. So, just light spray water on to the window screen and attach the trashbag over it.

How do you close a window with cardboard?

Use strong tape to stick the cardboard to the frame or the sides of the window, making sure that no gaps are left. Run the tape the full length and width of the window, so that the cardboard is fully secured. Alternatively, you can affix plywood to the affected area and use screws or a fixative to hold it in place.

Does cardboard insulate cold?

See, corrugated cardboard traps air in the flutes and, as a result, provides good insulation from freezing ground. Hence, why you see street vendors in places like New York and Chicago standing on pieces of cardboard.

What is the most insulating window covering?

Insulated Cellular Shades

Insulated shades contain one or more air layers in a honeycomb cross-section. Some can be adjusted from the top, from the bottom, or both. Insulated cellular shades are typically considered to have the highest R-values of all window coverings.

What is the cheapest insulation?

It's essential to wear protective clothing and a mask when installing fibreglass insulation to prevent any health risks. Overall, fibreglass insulation is the cheapest and most effective insulation option available, making it a popular choice for homeowners and builders alike.

What is the cheapest way to block heat from windows?

Applying weatherstripping around your windows is one of the quickest, easiest, and most cost-effective solutions to insulating windows and preventing heat from entering. Windows often have gaps that are common points for air leaks in homes.

Is it illegal to put aluminum foil on windows?

Emergency management agencies specifically recommend using aluminum foil-covered cardboard that goes between windows and drapes.

Why do people put cardboard in their windows?

A piece of cardboard can act as insulation for the window by covering up any openings or gaps between pieces of glass. This cardboard is a sturdy solution for the broken window. It keeps out cold and hot air, which will make your home more comfortable no matter what time of year it may be!

How to reduce heat from windows?

  1. Heat Blocking Window Shades. Putting up window shades is a quick fix for solar overheating. ...
  2. Blockout Roller or Panel Blinds. ...
  3. External Window Shading. ...
  4. Bubble Wrap Window Insulation. ...
  5. Heat Reducing Window Film. ...
  6. Combining Multiple Methods.

How to block 100% light from a window?

How to Blackout Windows Without Breaking the Bank
  1. Blackout Window Film. One of the most efficient and affordable ways to blackout windows is by using blackout window film. ...
  2. Blackout Curtains or Blinds. ...
  3. Cardboard and Aluminium Foil. ...
  4. Blackout Roller Shades. ...
  5. Privacy Film. ...
  6. DIY Blackout Panels.

How to block out sunlight in bedroom?

Now, let's explore some of the best light-blocking window treatments for your bedroom:
  1. Blackout Curtains.
  2. Plantation Shutters.
  3. Blackout Blinds.

How to insulate windows in summer?

Let us help you insulate your windows for the summer with some tips, tricks, and remodeling ideas.
  1. Add weatherstripping.
  2. Hang shades or blinds to insulate windows for summer.
  3. Apply insulating window films.
  4. Install exterior window awnings.
  5. Try shutters for your windows.
  6. Switch to energy-efficient windows.

Can you use plastic sheeting to insulate windows?

Savings in Energy and Money

They can also eliminate air leaks around the window if they extend over the woodwork, and this extra layer of plastic adds another layer of insulating air to reduce heat loss through the window.

Does aluminum foil keep heat out of windows?

Aluminium foil is both pliable, cheap and highly resistant to high temperatures. Spreading tin foil on any windows that receive direct sunlight can redirect the sun and heat away from your home.

How to cheaply insulate windows?

The Best Low-Cost Ways to Insulate Windows for Winter
  1. Re-Caulk or Re-Seal to Insulate Windows for Winter.
  2. Air Seal Windows With Foam Tape for Better Insulation.
  3. Install Low-E Storm Windows Over the Existing Frames for Better Insulation.
  4. Insulate Windows by Installing Plastic Film Around the Glass.

Does bubble wrap on windows really work?

According to the HowToGoSolar, a free online resource geared toward educating homeowners on the benefits of solar power and energy efficiency, bubble wrapped windows show insulating improvements that are 50% better on single-glazed windows, cutting utility bills almost in half.

How to winterize windows from the inside?

How to winterize windows from the inside
  1. Leverage thermal curtains. Thermal window curtains are heavier than traditional curtains and feature a foam lining that offers additional insulation. ...
  2. Use a draft stopper. ...
  3. Install window film. ...
  4. Seal and caulk the windows. ...
  5. Insulate your windows. ...
  6. Consider an upgrade.

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