Easy Tips on How to Fix Gap between Window and Frame

Windows don’t only look good; they shield us from weather elements. But when cold air gets through the windows into your home, something has gone wrong with its protective ability.

Learning how to fix gap between window and frame is the best way to solve the problem. A window and frame gap gets worse when you ignore it.

So, taking steps to correct it immediately will reduce the heating bill and control its effect on your wallet. Fixing the gap is a simple process and can be completed quickly. You can see this video for some quick tips.

Why is There a Gap Between Window and Frame?

The cause of the gap between window and frame is the expansion and contraction of the frame. Window frames made of vinyl or wood tend to expand at various rates more than the materials used by window manufacturers.

Other causes could be; bad workmanship during fitting, and the house’s natural settling that makes the mortar crack and creates a gap.

No matter what causes the gap, there are many options that one can choose to correct it and still enjoy enough brightness indoors.

Different Ways to Fix Gap between Window and Frame

You can apply lots of methods to fix window gap when it happens. Such methods include:

Fix Gap between Window and Frame

Method 1: Foam Backer Rod

A foam backer rod works well to reduce the effect of cold temperatures inside the home. It comes in two types; open-cell varieties and closed-cell varieties.

The best variety to use for sealing hung windows and frame gaps is the closed-cell because the open cell variety can take up and retain moisture. You may follow these steps to use a backer rod:

  • Use a brush to clean the affected area to remove dust and dirt.
  • Get the foam backer rod (it should be wider than the gap) and place it in the hole.
  • Press it into the gap firmly and ensure you make a tight seal.

Method 2: Expanding Foam

Expanding foam is an excellent solution to filling enormous gaps between window and frame. It creates an excellent moisture barrier between the filled area, and it doesn’t break or crack as you make moves while working. The steps include:

  • Clean the area properly to remove dirt.
  • Target the gap and inject the foam directly into it till the foam fills the gap and expands outside it.
  • Allow the foam to keep expanding until it feels all the cracks and openings around the hole to make a fine seal.
  • Let the foam set.
  • When it has set completely, trim and sand it down; to enable you to get an even surface.
  • Plaster it, and apply paint over it.

Method 3: Spray Polyurethane Foam

Spray polyurethane foam (SPF) expands and solidifies when sprayed on a surface, making it great for sealing gaps like the one between a window and frame. The chemical can also reduce heat levels in buildings because it has low conductivity. The steps to apply SPF are:

  • Clean the area around the window and frame.
  • Shake the spray foam can.
  • Turn the spray can upside down and press down the valve to activate the content.
  • You may wet the area with the gap to quicken curing.
  • Spray the SPF foam on the area continuously without breaks ensuring you don’t spray excess.

Let it harden.

Method 4: Removable Caulk

Removable caulk is excellent for sealing gaps in drafty windows to save energy. One of its many features is that it is easily removable when you need cold air; you can apply it to reduce temperature and peel it off during spring for fresh air.

  • Clean the area you want to seal to remove dirt.
  • Measure the area with a measuring tape.
  • Measure out the same quantity of the removable caulk.
  • Place and press it down firmly to help it stick.

Method 5: Using Mortar

Mortar is an excellent window frame gap filler, especially for wide gaps. Numerous types of ready mixed mortar are available in small bags for simple home jobs like these. To use mortar to fix the gap, you may follow the steps below

  • Buy the quantity of mortar you need.
  • Follow the manufacturers’ instructions to mix it properly and set it aside.
  • Clean the gap with a stiff brush to rid it of dust and dirt.
  • Make the inner part of the gap damp by spraying water there.
  • Scoop the mortar with a small trowel and use it to fill the gap by pressing it.
  • Smoothen the mortar with the face of a trowel. Make it level with the brickwork around it.
  • Leave the mortar to dry.

Method 6: Rope Caulk

Rope caulk comes in various colored strips or tapes that are easily removable anytime you want it out. It is inexpensive and easy to install on brick walls and metal window frames to seal gaps. The steps to using these air-sealing tapes to fill gaps are: 

  • Use a sturdy brush to clean the window and frame area where you plan to apply the rope caulk.
  • Ensure the area is dry to enable the rope caulk to stick well.
  • Measure the area you need to seal.
  • Measure out the same quantity of rope caulk you need and cut it out.
  • Place it on the area and hold it down firmly to make a seal.

Method 7: Multipurpose Gap Filler

Multipurpose gap fillers also help fix gaps between windows and frames to reduce heating costs and make the home more comfortable. Steps to use it include:

  • Clean the area you want to fill to remove dust and loose particles.
  • Use a putty knife to clear old paints that may affect adhesion.
  • Remove the seal above the multipurpose gap filler.
  • Cut the nozzle almost the same size as the gap.
  • Fix the nozzle to the cartridge’s top, and also fix a caulking gun to it.
  • Press the caulking gun trigger to spray the gap filler into the gap.
  • Clean off any excess of the product with a water and soap solution and a damp cloth.
  •  Leave the area to cure for an hour, then paint.

Method 8: Frame Sealant

Frame sealant comes in colors such; as brown, white, transparent, and grey; you can buy the ones in a tube, which you can apply when you turn up the screw cap or buy the type that comes in a tube and fix in a cartridge gun before application.

The steps to applying a frame sealant as an airtight barrier in windows include:

  • Use a stiff brush to brush off dirt around the frame area to make it clean.
  • Use scissors to cut out the nozzle fixed at the frame sealant’s tube. The cut should be further away from the tip if the gap is enormous.
  • Direct the nozzle to the gap and smoothly apply the sealant. Ensure to apply it all around the frame, not just on the gap.
  • Allow the sealant to dry for about three weeks.
  • Paint over it when completely dry if there is a need.


It is necessary to ensure that the surrounding area is clean before applying any method of sealing the gap; The reason is that dirt, dust, and loose particles may affect the sealing materials, and they won’t stick properly.

Also, it is best to apply the expanding chemicals in moderation because of their expanding ability. Spraying so much of it will amount to wastage.

Frequently Asked Questions (FAQs)

Q: How do you fill the gap between window sills and windows?

You can fill a gap between window sills and windows by caulking or applying an expanding foam if the space is large. Caulking involves the steps below:

  • Clean the area around the window and sill where you want to caulk.
  • Ensure the place is dry for proper sticking of the caulk.
  • Measure the window and seal the area that has the gap.
  • Measure out the same quantity of caulk you need and cut it out.
  • Position it in the workplace, and apply enough pressure to make a seal.

The steps to applying expanding foam are:

  • Remove dirt and dust from the area.
  • Fill the gap by spraying the expanding foam into it and allowing it to spread.
  • Let the foam spread more until it fills all the spaces and openings around the hole to make a fine seal.
  • Leave the foam to set.
  • After setting, trim off the excess foam, and sand it down to make it smooth.
  • You may plaster and paint over it.

Q: Can I use filler instead of putty?

Wood filler and wood putty may look alike, but they’re not the same. They have different compositions and perform various functions; therefore, it is not advisable to use them interchangeably.

Filler is best for indoor repairs because it consists of organic materials. It is mild on wood even when you apply a large quantity and also dries faster and tends to break when the wood outside goes through expansion and contraction.

Putty, on the other hand, is best for outdoor repairs. The reason is that it can expand and contract with the wood due to temperature changes. It doesn’t dry or breaks.

Q: How do you use wood filler on a window frame?

You can use wood filler on a window frame by following these simple steps:

  • Remove the rotten part of the window frame’s wood with the help of a hammer and chisel.
  • Give the area a thorough cleaning to get the workplace ready.
  • Apply the wood filler to the area and allow it to dry.
  • Sand the window frame when it has dried and coat with another layer of wood filler.
  • Let it dry.
  • Smoothen it to get an even and flat surface of the window frame.
  • Finish off by painting with the wood color.

Wrap Up

It is not uncommon to notice cold air leak into the building even when you close the windows. This little problem can lead to high heating bills, but following the tips above on how to fix gap between window and frame will help you keep drafts away from your home.

Related Content

Melia Karneva

This is Melia Karneva, a mother of two young gentlemen. A stay-at-home mom, she loves nothing more than cleaning and cooking for her family. Her true passion, is writing, which she pursues with great zeal. She loves putting pen to paper (or fingers to keyboard) in her spare time. Karneva thinks of herself as a Renaissance woman - she can do many things but doesn't like to brag about them.

Recent Posts