Complete Guide to Door Core Types

As someone in the field of architecture and design, when you look at a door, you know there’s a lot more to it than what’s on the surface. It can look beautiful and stylish, but the door core determines much about its functionality and durability. This guide will break down the different types of cores for interior wood doors and where to specify each one.

Hollow Core Wood Doors

Hollow core doors are not completely hollow, but rather house a cardboard honeycomb inside. Hollow cores are lightweight and easy to transport and install. They can be less susceptible to expansion and contraction than a solid wood door, but that is where the advantage ends. Hollow doors typically get damaged more easily and are harder to repair when they do. They provide little in the way of insulation and cannot be rated for fire or acoustics.

They are most often selected for interior applications in the multi-family and hospitality markets. They might work well in out-of-the-way locations of hotels or offices, like lesser-used storage rooms. Masonite Architectural offers the Cendura series with hollow cores.

Cendura Wood Veneer Surface Hollow Core Stile and Rail Door Section

Structural Composite Lumber Cores

For heavier use and longer life, structural composite lumber (SCL) is often a viable option. SCL offers a durable, extra heavy-duty rated core made from strands of wood bound with resin. SCL cores include fire ratings to 20 minutes.

An SCL door core works well for an interior door that needs to make a strong visual impression and last a long time, but without the need to provide high-level performance. Explore the SCL core in our Aspiro stile and rail doors, which make great statement doors. SCL is also widely available for flush doors.

Vics remodeled dining room with Masonite Architectural stile and rail doors in the background.

Particleboard Cores

Particleboard is made from ground wood chips bonded with adhesive. Particleboard door cores work for many applications. While it increases the weight of the doors, it also increases durability.

Typical particleboard cores are lower density and great for flush wood doors. They can be specified with a 20-minute fire rating, so can work well for offices. For more versatility, an extra heavy-duty (EHD) particleboard core offers 45-minute fire ratings, for just about any place where you need a fire-rated door. Their higher density makes them well suited for heavier surface-mounted hardware as well. You can specify particleboard or EHD in many of Masonite Architectural’s interior wood doors.

MDF Cores

For a door core that is even denser than particleboard, opt for medium-density fiberboard (MDF). Its glued wood fibers make it suitable for a broad selection of applications. Masonite Architectural uses it for Cendura stile and rail doors, a budget-friendly choice with a classic to modern look and seven standard paint colors. An MDF surface helps ensure smooth paint application.

Hotel room with MDF Square Groove doors.


For an environmentally friendly choice, just about anywhere you need to specify flush wood doors, agrifiber makes a good option. Made from rapidly renewable plant cellulose, agrifiber is more sustainable than wood and meets LEED standards. It also lacks the bonding agents found in particleboard, so it plays a role in improving indoor air quality. Agrifiber door cores comply with WDMA standards and extra heavy duty performance requirements. They can still meet fire-ratings up to 45 minutes. Agrifiber cores are available in Masonite Architectural’s custom flush wood doors.

Fire-Rated Cores or Mineral Cores

Fire-rated cores, also referred to as mineral cores are made from non-combustible materials such as minerals and fiberglass to slow the spread of fire and smoke from one part of a building to another.

Fire-rated doors are required for key areas in schools, hotels, and most other public spaces. They can be specified for 20, 45, or 90 minutes. Even with glass lites, many wood doors styles can be specified with a 20-minute fire rating.

In 2019, Underwriters Laboratories—a third party research and testing company—honored Masonite Architectural with its Dedication to Safety award, in recognition of wood door fire safety.

cross section of fire rated door

Door Cores for Performance Needs

Interior wood door cores can be specified to meet a variety of other requirements, like STC-rated doors to reduce sound transfer, lead lined doors to provide a radiation shield, or attack-resistant doors, which use an EHD or SCL core for added strength.

When you’re ready to find the perfect doors, with the combination of the surface type and core type to meet your project’s demands, reach out to your Masonite Architectural rep or request samples.