How To Fix A Gap At The Bottom Of An Exterior Door

Ideally, an exterior door should not have any gap at the bottom. This maintains the temperature you have set and keeps out crawling insects and creatures that may try to find their way inside your home. However, a gap can appear, letting in cold or warm air, making your home uncomfortable. What causes these gaps, and how can you fix them? We've gained knowledge from experts to share with you. 

You can seal the gap underneath your exterior door by installing a door sweep.

Door sweeps come in three variations. Each has its unique features for specific purposes. Keep reading to learn how to fix the gap under your exterior door, why there are gaps, and the cost of repairs.

front door opening - How To Fix A Gap At The Bottom Of An Exterior Door

Can You Fix The Gap Beneath Your Exterior Door?

In front of house which decorate and design in modern with door that made from wood and floor made from parquet, with the garden on the right side

Your exterior door should not have any gap at the bottom so that it can keep out the effects of the elements from getting inside. 

Door sweeps are sometimes known as draft stoppers that are made from plastic, rubber, or bristles like those found in a brush. There are three types of door sweeps; strip, under-door, and bristle. Let’s go through each to gain a better understanding and decide which to install.

Strip Door Sweeps

These strip door sweeps are easy to install and come with an adhesive backing that you can stick to inside or outside the exterior door. You can also affix the strip onto plastic or rigid metal installation guide, which you install by fastening it to the bottom of the door.

Whichever you choose, the idea is to install your door sweep at the correct height allowing only a gentle contact between the floor and the strip that does not create friction preventing the movement of the door.

Under-Door Sweeps

Under door insulation brush seal close up shot against white background.

An under-door sweep provides a very tight seal between the bottom of your door and the floor.

They look like an uppercase “B” that has two round pieces on each side of the door but facing upwards. They are made from a soft foam that makes them flexible. 

Bristle Door Sweeps

This concept is the same as the door sweep. It is made from bristles like those in a brush instead of a solid strip of plastic or rubber. They don’t have friction and are not as effective as the strip or under-door sweeps.

We will take a look at how to install a strip door sweep and an under-door sweep.

How To Install A Strip Door Sweep

front door opening

Strip door sweeps come in a variety of shapes and are made from different materials. In this case, we'll install an aluminum strip that has a vinyl strip attached to it like the one shown below:

Check out this product on Amazon.

This is an easy method that you can do yourself as you do not have to remove the door. However, do not attempt if you do not have the skills. Instead, call a professional.

The steps to fixing the door strip include:

Materials and tools needed

  • Aluminum strip with vinyl attached
  • Pencil
  • Tape measure
  • Drill bits and driver bits
  • Cordless drill
  • Scissors
  • Hacksaw


  1. Measure the width of the door using your tape measure, taking into account the doorstep.
  2. To cut the door sweep frame, mark the measurements you have taken on the aluminum using a pencil.
  3. Cut at the point you have measured using a hacksaw and stop when you reach the sweep insert.
  4. With your scissors, cut the vinyl part of the insert. 
  5. Mark the door sweep drill holes. Close the door, and place the sweep at the bottom. Mark at the center of the oval holes of the door sweep. 
  6. Drill pilot holes. Identity a drill that is narrower than the screws, which came with the door sweep kit. Drill the holes where you had marked. 
  7. Attach the door sweep. Firmly hold the door sweep on your door, and drill the screws onto the door. Don't tighten too much such that the aluminum frame warps or the screw heads get stripped. 
  8. Test the door sweep by closing and opening it a couple of times, and watch how the door sweep behaves. It should touch the threshold without causing any friction so that it is easy to close and open the door. 
  9. Adjust the door sweep. If needed, you can adjust the sweep either up or down by slightly loosening the screws.

A problem that can occur with the installation of a door sweep is when the door is uneven at the bottom. There will still be a gap in some sections under the door. In this situation, you might have to re-align the sweep at an angle to seal the gap completely. In some cases, the door might have to be removed and re-aligned properly. 

Below is a video that shows you how to install a strip door sweep:

How To Install An Under-Door Or Wrap-Around Sweep

It is very easy to install this type of door sweep like the one shown below.

View this under-door strip on Amazon.

This is a good choice if you have a large gap underneath your door. After purchasing your under-door sweep, slide it slowly under the door so that it fits firmly.

Once you are sure it has closed the gap, you can drill some pilot holes in the sides and install screws to hold it in place. 

What Are The Benefits Of A Door Sweep?

Door sweeps are made from various materials and are designed to fit snugly between under the door and the floor.

They not only keep away the elements such as rain and snow from getting into the house, but they also help keep your home comfortable.

So, it is worth installing a door sweep? Let us look at the benefits below:

Protection From Pests

Insects will always try to find their way into your home through any gap they can find, including the gap underneath your door. If you don’t do something about it, pests and insects can be a nuisance to the occupants or even cause damage to your furniture.

A door sweep does a great job of preventing those little creatures from getting in.

Keeps Out Moisture

The gap under your exterior door can allow moisture into your home creating a good breeding ground for mold.The mold could be disastrous as it could end up damaging your furniture or any other upholstery.

Stops Noise

Door sweeps are not only excellent at keeping the heat and cold out but help prevent too much noise from coming in into your home. It is essential to your business if you want a quiet place to work from.

Reduced Energy Costs

If warm air leaks outside through the gap under the door during the cold season, the HVAC will have to work extra hard to maintain the warmth in the house.

Likewise, during the warm season, the gap could let out the cool air produced by the AC, making it work harder to condition your home, thereby increasing the energy costs.

However, if the gap under the door is sealed well, cold or warm air will not be able to escape or get in, thus lowering your energy bills.

Improved Air Quality

A closed gap under your door keeps out any pollutants from outside that could decrease the quality of the air. Coupled with the AC that filters out dust, dirt, or any other contaminant, it creates cleaner air.

Increased Comfort

As seen above, a sealed gap will help condition your home effectively. The temperatures you set will be maintained at the level you desire. Also, a sealed gap keeps out pests and other pollutants from your home.

Cost Of Repairing A Gap Under The Door

Classic fiberglass prehung black front door, raised panels, white frame, sill, jamb separating the divided sidelights, transom windows separated by narrow white grilles

It’s good to know how much you are likely to spend when installing a door sweep. 

Depending on the material used to manufacture the door sweep, the costs can range from $3.50 to $18.30 per unit. Installation depends on the type of sweep and the work involved that costs between $60 and $120 for each unit installed.

You may opt to do the installation yourself, but it can be risky if you are a novice or if you don’t have the skills. You are better off calling a professional who will do a good job vis-à-vis the amount you will spend. 

In Closing

A gap under your door can occur by wear and tear or damage. It can let in pests or pollutants from outside, making your home uncomfortable.

Sealing the gap will not only reduce the effects of the weather elements but will reduce your energy bills. 

As you plan to install a door sweep, it's good to know how much money you will spend. Thus, you will not be caught off guard by unexpected expenses that could come up abruptly. 

How many door sweeps are there in the market? Click here to know more: "Types Of Door Sweeps And Bottom Seals."

What is the correct space needed between the door and floor? To find out more, click on this link: "How Much Space Between Door And Floor?"

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