How Big Of A Gap Should There Be At The Bottom Of A Door?

I know from experience that if a door is not installed at the right height, you will run into problems in the future. If the framer gets the measurements wrong, then you will need to spend extra time and money to fix it which is why pre-hung doors are often recommended. Right now, you may be wondering just how big of space there should be at the bottom of a door? Well, I have the answer for you below:

The gap at the bottom of an interior door should be 2 inches from an unfinished floor. Over a finished floor, the gap should be between ¾ to ½ of an inch, depending on the type of floor you have. The gap at the bottom of an exterior door should be almost nonexistent. This helps to prevent the outside elements like wind, rain, snow, sunlight, and bugs from getting into your home.

How Big Of A Gap Should There Be At The Bottom Of A Door?

Now that you know how much space is required between the bottom of a door and the floor/ground, let us explore this topic further and in more detail below. We will discuss why a gap is necessary in the first place as well as how to fix a gap that is either too big or too small. I will also explain how much space is required at the bottom of a fire door and whether (or not) a door sweep should touch the floor.

So, if you are ready to learn more, then please continue reading…

* This article may contain affiliate links. As an Amazon Associate, I earn from qualifying purchases. 

How High Should An Interior Door Be From The Floor?

Interior doors should clear a finished floor by ¾ of an inch to ½ of an inch.

The only time you would require a greater threshold height would be in the case of an uneven floor.

When installing, the frame should be 3/16 of an inch wider than the slab with 1/16 of an inch clearance on the hinge jamb and 1/8 of an inch clearance on the strike jamb.

This will ensure the door swings freely without rubbing on the flooring material.

How High Should An Exterior Door Be From The Ground?

Exterior doors usually come with 1 and ¼ inch of threshold height, though this can vary depending on the style and brand of the door.

As most subfloors are about ½ an inch from the ground, you must adjust the door accordingly by either raising the jamb up higher or cutting the jamb at the bottom so that the door swings easily without catching or rubbing on the flooring material.

The idea is to avoid cutting the door itself, whenever possible.

Why Do Doors Have A Gap At The Bottom?

The space or gap at the bottom of a door is necessary and acts as an air return when the door is closed. This is especially important in newer homes with central heat and air conditioning.

Without the gap, there would be little to no airflow through the registers or ductwork.

This would ultimately affect the balance of your HVAC (heating and cooling) system and have a negative impact on the comfort of your home.

It could also impede the efficiency of your furnace, causing your heating bill to spike significantly.

How Do You Fix a Gap at the Bottom of a Door?

To fix a gap under a door, you can first try to tighten the hinges. If that does not work, you can try removing the screws and adjusting the alignment.

When doing so, replace the old screws with newer, larger ones to help reinforce the hardware and keep the door from shifting.

Yet another option is to remove old weatherstripping and install a new one.

You can use felt rolls, corner pads, sticky foam tape, rubber, silicone, vinyl, or Kerf’s Weatherstripping.

Begin by removing the worn-out or incorrectly installed weatherstripping and wipe down the door frame with rubbing alcohol – this helps remove any residual product while helping the new one to adhere properly, creating a secure seal.

As well, you can try using a door sweep to fix threshold gaps.

To attach it correctly, simply follow the manufacturer’s instructions or do the following:

  1. Measure the door
  2. Mark and cut the door sweep to length, if necessary
  3. Drill the pilot holes
  4. Attach the sweep loosely to the bottom of the door
  5. Secure to the door by tightening the screws

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Your final option would be to cut the door itself along the bottom.

This is usually done if the gap is too small and the door is rubbing against or catching onto the flooring material.

This should be your last resort if all other attempts to fix the gap fail.

What Should the Gap be at the Bottom of a Fire Door?

For fire doors with cold smoke control, it is recommended that the gap at the bottom be less than 3mm in height or fitted securely with a threshold seal.

However, some manufacturers claim that a gap of up to 8mm is permissible.

The consensus seems to be a gap of no more than 4mm and no less than 2mm to ensure adequate space for the intumescent strips to activate in case of a fire and to prevent the smoke seal strips from being damaged by the opening and closing of the door.

How Much Clearance Do You Need Between a Door and Carpet?

When using a pre-hung door, you need a ¾ to ½ inch gap at the bottom (depending on the thickness of the material) to prevent the door from snagging on, rubbing against, or wearing down the carpet.

How Much Clearance Do You Need Between a Door and Laminate Flooring?

If using a pre-hung door, you need at least a ¾ gap at the bottom to prevent the door from rubbing against (and possibly damaging) the laminate flooring.

How Much Clearance Do You Need Between a Door and Hardwood Flooring?

When using a pre-hung door, you need al least a ¾ inch gap at the bottom to keep the door from rubbing against (and likely scratching) your hardwood flooring.

How Much Clearance Do You Need Between a Door and Ceramic Tiles?

If using a pre-hung door, you need at least a ¾ inch gap between the bottom of the door and the ceramic tile flooring.

Should a Door Sweep Touch the Floor?

A door sweep is used to seal the gap between the bottom of the door and the threshold. It helps save money on heating and cooling bills by preventing outside air, light, dust, moisture, and insects from getting into your house.

This device is mainly used on exterior doors and is installed on the inside of the door as most entry doors are ‘in-swinging.’

The door sweep should be installed in such a way that it seals the gap yet does not touch the flooring material.

When the door swings open or closed, the door sweep should not catch on your carpet or slide across laminate/hardwood flooring or ceramic tiles.

If it rubs against your flooring, it could wear it down or damage/scratch it over time.

Read also: What Direction Should I Lay My Laminate Flooring?

Conclusion

To sum things up, the gap at the bottom of an interior door depends upon the type of finished floor you have and ranges from ¾ to ½ of an inch.

The gap at the bottom of an exterior door should be almost nonexistent to keep the outside elements from getting inside your house.

It is best to use pre-hung interior doors whenever possible as they are easier to install and come with manufacturer instructions – usually, a large sticker (wrapped in plastic) displaying the recommended framed opening somewhere on the door.

Hopefully, this article has been of help to you. Thanks for reading and good luck with your interior and/or exterior door installation.

Cheers, tools owners!

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Hi there! My name is Jack and I write for ToolsOwner. I have a passion for everything related to tools and DIY projects around the house. You often find me in my workshop working on new projects.