What Is the Difference Between an Interior and Exterior Door?

Post by manhattandoor on June 15th, 2020

Updated June 30, 2023

What differentiates an interior door from an exterior door? It is not just the location in a building. There are many differences between interior and exterior doors that even contractors can overlook. Since one provides a barrier between interior spaces and the other between interior and exterior environments, the physical properties of these different door types must serve unique purposes.

A door is an important mechanism designed for specific uses in certain situations. That is why choosing the proper door types for your buildings requires help from our team who knows doors. We at Manhattan Door understand what constitutes interior vs. exterior doors, and can help you make the correct choices for your applications.

Interior vs. Exterior Door Appearance

Interior and exterior doors typically differ in appearance. The visual characteristics of each type of door include:

Interior Doors

• Used as entrances and exits between rooms inside your building
• Typically lighter and thinner than exterior doors
• Generally cost less than exterior doors
• Can include wooden, metal, glass or a combination of these features
• Typically come in a single-door construction
• Can feature decorative panels on both sides of the door

Exterior Doors

• Function as the main entrance and exit to your building
• Provide insulation and a temperature barrier between your building and the outside
• Require special treatment to prevent weathering and related damage
• Treated to withstand high moisture levels
• Often come in double door constructions
• Usually have more security features than interior doors
• Can feature decorative panels on the outside

Material

Interior and exterior doors share many of the same materials, yet there are typically a few key differences between each.

Interior Doors

• Normally feature a hollow core
• Can be made from glass, metal, wood, fiber wood or a combination of these materials
• Mostly offered in single-material construction varieties

Exterior Doors

• Made to withstand the elements and protect your building’s interior from inclement weather
• Feature tougher, more moisture-resistant adhesive
• Normally feature a solid core
• Can be made from a combination of glass, metal, steel and wood
• Usually feature a reinforced metal door frame

While interior doors are usually made from only one material, exterior doors need multiple construction layers to provide enough insulation and protection from the elements.

Thickness Differences: Interior & Exterior Doors

Exterior doors are constructed to be much thicker than interior doors due to their function. While interior doors are subjected to far less wear and tear, exterior doors require an extra thick core, usually wooden, to keep out the heat and cold. Exterior doors almost always include a thick layer of veneer for insulation and protection against weather damage. While interior doors are made for frequent, easy use, exterior doors provide a protective barrier for the building.

Core Construction

To properly function as barriers between the inside and outside, exterior doors have a solid core construction. Exterior doors usually consist of wood or woodgrain cores surrounded by layers of steel or metal for maximum temperature control and security features.

Interior doors are designed to be lighter and thinner than exterior doors and often feature a hollow core. However, more expensive interior doors include a type of wood fiber core or a honeycomb-like interior to help muffle sound.

Insulation Differences: Exterior and Interior Doors

In addition to providing a secure barrier between a building’s interior and the outdoors, exterior doors are constructed with optimal insulation capabilities. Their multilayered construction typically features some form of insulation. Steel doors, for instance, will usually have foam cores to regulate temperature.

Interior doors can also have insulation, although this is not common. However, interior doors with solid core construction can provide moderate draft protection.

Sizing Requirements

Because exterior doors serve as the main entrance and exit points in a building, they are almost always larger and heavier than interior doors. Due to their extra thickness, exterior doors are designed with protection from the elements in mind rather than usability. Today, many exterior doors also include ADA-compliant features, such as automatic opening buttons, due to their heavy construction.

Conversely, interior doors do not need to be as thick or heavy as their exterior door counterparts and are normally uniform in construction. If you are wondering whether you can use an interior door as an entry door that comes in contact with the exterior or vice versa — the answer is almost always no. Each door type is designed for unique purposes. Plus, using an interior door on your building’s exterior will result in rapid wear and tear — and an outrageous heating bill.

Choosing Your Interior Door

If you are a contractor or building project manager looking for the perfect interior doors for your construction project, browse our collection of customizable, high-quality interior doors. Choose from an array of durable, beautiful materials that meet your design and construction needs — we are always here to help.

Contact us today if you have any more questions about the differences between interior and exterior doors.