In general, there should be a 2 inches gap from an unfinished floor and there should be ½ inches or ¾ inches gap from a finished floor, depending on the type of floor you have.
Gaps from the bottom of exterior doors should almost be non-existent to prevent weather elements and bugs from getting into your home.
Now that you know how much of a gap is required at the bottom of the door, let us explore this topic further.
If a door is not installed at a proper height, it can cause a lot of problems in the future. If the measurements are wrong, you may need to spend extra money and time just to fix it, that is why you need to follow standards and rules to be able to calculate the measurements needed when installing a door.
Doors need a gap at the bottom because it allows airflow when the door is closed, it also acts as a return air duct. This gap is particularly important in newer homes with air conditioning and central heat.
Without this gap, there would be less or no airflow through the ductwork. In other words, if there is no gap under the door, air will not circulate well and this will negatively impact the comfort of your home because your HVAC systems will not work properly.
On the other hand, gaps are also filled in to prevent the heat or cold air from escaping and to keep weather elements and bugs from getting inside your house.
Gap Under Interior Door
Interior doors should have a ¾ inch or ½ inch gap at the bottom. However, if the floor is uneven, a greater threshold height may be required.
Upon installation, your frame should be 3/16 inch wider than the slab with a 1/16 inch hinge jamb clearance, and ⅛ inch strike jamb clearance to ensure that the door can swing smoothly without rubbing against the floor material.
Gap Under Exterior Door
Standard gap between exterior door and floor usually have 1 and ¼ inch threshold height, however, this can depend on the style and brand of your door.
Most subfloors have a ½ inch gap at the bottom, so you have to adjust the door accordingly by either cutting the jamb at the bottom or raising the jamb higher to ensure that the door swings smoothly without rubbing against the floor. Additionally, this can also prevent you from cutting the door.
The recommended gap at the bottom of fire doors, with cold smoke control, is less than 3mm in height or should be fitted securely with a threshold seal.
However, according to some manufacturers, a gap of up to 8mm is acceptable.
To ensure adequate space for intumescent strips to activate in case of a fire, there should be a gap of no more than 4mm and no less than 2mm as this could also prevent the smoke seal strips from getting damaged when opening and closing the door.
For fire door codes and standards check with NFPA in the United States or in United Kingdom the London Fire Brigade is a good resource for fire door safety.
How high should a door be above carpet
There should be a ¾ to ½ inch gap at the bottom of a pre-hung door to prevent it from rubbing against, snagging on, or wearing down the carpet.
The gap between a door and laminate flooring
There should be a ¾ gap at the bottom of a pre-hung door to prevent it from rubbing against and damaging the laminate flooring.
The gap between a door and ceramic tiles
You need at least ¾ inch gap between the bottom of a pre-hung door and ceramic tile flooring.
The gap between a door and hardwood flooring
You need at least ¾ inch gap between a pre-hung door and the hardwood flooring to prevent the door from rubbing against and scratching the flooring.
Materials used to fill gap under door threshold
For sealing gaps under your front door, you can use some grout. This is a dense cement mixture that can fill the gap between the floor and the threshold, however, you should only use grout if you have a door that is at least an inch thick.
Non-compressible or non-shrink grout will help add protection against water leaks and other damages.
The use of a low expansive foam can also help eliminate any gaps that could potentially be a breeding ground for bugs and pests. Furthermore, it can help perfectly align your door with the floor.
Wooden fillers made of oak or maple can also be used to fill the gap between a door and the bottom of the door.
This is one of the most affordable materials you can use to fill a threshold gap. You can easily buy such stoppers at the hardware stores or make your own.
Rubber is another material that you can use to fill in a threshold gap. A rubber weather strip can help keep the gap from getting bigger and can keep the elements out.
Rubber is a material that can be easily cut, installed, and removed, that is why it is also ideal for making DIY projects.
Another material that you can use to fill in the gap underneath the threshold is cork. It is also one of the best options because they are inexpensive, renewable, and sustainable. It can act as a great insulator and is a highly weather-resistant material.
Installing cork under a threshold can prevent mud, moisture, and cold air from getting in your house.
Frequently Asked Questions
If you think you need to fix a gap under your door, then you can try tightening the hinges first and if that does not work, try removing the screws and adjust the alignment.
To help keep the door from shifting, replace the old screws with newer ones as this can also help reinforce the hardware.
Another option to fixing a gap at the bottom of your door is to remove old weatherstripping and replace it with a new one. Use felt rolls, sticky foam tape, corner pads, silicone, vinyl, rubber or Kerf Weatherstripping.
Your final option would be to cut along the bottom of the door, which is usually done if the gap is so small that the door is rubbing against the floor. If all other options failed, this should be your last resort.
Should the door sweep touch the floor?
A door sweep is a long strip of metal holding a seal made of either a neoprene material, silicone, or a nylon brush. It is used to seal in the gap between the bottom of a door and the threshold to prevent outside light, air, dust, moisture, and insects from getting in, plus it can help you save money on heating and cooling bills.
Door sweeps are mainly used for exterior doors and are installed on the inside of the door because most of these entry doors are “in-swinging”. However, a door sweep should be installed in a way that it can seal the gap yet not touch the flooring material to avoid wearing it down over time.
When a door is open and closed, the door sweep should not rub against the ceramic tile or laminate/hardwood flooring and should also not catch on your carpet.
Should there be a gap between a door and the frame?
For the door to be opened and closed properly, there should be a 2mm gap between the sides and top and an 8mm gap between the door and the floor.
A gap between the door and a frame allows heat loss and loss of cold air-conditioned air, which can increase energy consumption. Additionally, it can let in pests, rain, and moisture which can damage your home’s interior.
Even though this gap between the door and the frame may not seem that important, you should still pay attention to it in order to avoid unnecessary heating or cooling bills.
To sum things up, the gap at the bottom of an interior door ranges from ¾ to ½ inch, depending on the type of floor you have. On exterior doors, the gap should almost be non-existent to keep outdoor elements from getting inside the house.
Make your home more comfortable by determining if you need to adjust the alignment of your door or if you need to install new weatherstripping or a door sweep. You can fill the gap between a door and the threshold by using a rubber strip, grout, cork or wood.
However, you have to make sure that your door can still be opened and closed smoothly and will not damage your flooring and the door itself.
Even though gaps may not seem that important, they can still cost you in the long run. Therefore, you have to make sure that they are filled in properly, using the right material and measurement.