Internal Doors: Structure and Styles Explained

It’s important to choose the right internal door for a building project, balancing the aesthetic needs of the space with size and strength requirements. Whether you’re looking for structural or visual ideas for your building project, this guide to internal doors covers the key options available, including the types, designs, and sizes.

Types of Internal Door Design

There is a range of interior doors available in the UK, with both standard hollow or solid core options, alongside other specific choices.

Hollow Core

A hollow core interior door will be built from a sturdy wooden frame with facing panels on each side. The core of the door will be filled with loose materials like paper, cardboard, or plastic. This will be the weakest of all options, meaning they are suitable for certain indoor environments like houses but are less suitable for more heavy-duty locations. They also lack the thermal and acoustic insulation of solid doors, allowing both noise and heat to escape or enter through them easily. They are however the most affordable option, which over the course of a larger project can be a huge benefit.

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Solid Core

These doors will still be built with a facing veneer on each side but will have a solid central core, typically made from a composite wood like MDF. This means that they can have the look and feel of an authentic wood door. Oak veneers are a popular choice, but you’ll find a range of options including ready-finished white doors. They are more durable, with higher insulation levels than hollow choices. The drawback is that they are a higher price than hollow core options, though they will still be cheaper than solid wood.

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Solid Wood Doors

These solid doors will be made from authentic wood, usually built from several pieces of wood attached together. This will be a sturdy and attractive option that is designed to last, with a fantastic authentic grain. Options like internal oak doors will keep their value over time, so can be seen as an investment in a property. It’s worth keeping in mind the higher price tag of solid wood doors, and that they can have issues with warping over time. 

Glass and Metal Doors

Another popular choice within commercial environments is glass and metal doors, which offer a stylish look and visibility, helping larger buildings to remain light. The size and placement of metal elements can vary, from a frame at the top and bottom to small sections at the hinge joints. These doors will need to be cleaned frequently and will be unsuitable for private spaces, though frosted options are also available.

Folding Doors

Folding doors will be able to fold onto themselves to open the doorway. Options include bi-fold doors which will fold in half, and other larger options. These can be used to bridge two spaces in a house, such as a kitchen and dining room. Smaller internal bi-fold doors will be a great way to make the most of limited space.

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Sliding Doors

Sliding doors will also avoid intruding into spaces when opened, with the door mounted on a sliding system. Double internal sliding doors are also available, and are referred to as barn doors. These can bring a novel look to an inside space.

Internal Fire Doors

In all commercial and many domestic buildings, internal fire doors will be needed to meet building regulations. The location and strength of fire doors will be determined by a professional, with FD30 and FD60 doors offering 30 and 60 minutes of fire protection respectively. Fire doors will be solid core, and will come as pre-finished doorsets, with fire-resistant frames, hinges, and masonry, alongside seals around each side and signage. Meeting the strict codes of fire doors within a building is essential, and failing to do so risks the safety of inhabitants and legal punishment.

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Interior Doors Visual Designs

While choosing the ideal internal doors, there will also be a range of visual options alongside structural ones. These can completely change the feel of a room, from glazed panels in an office to flush doors in a home.

Flush Internal Doors

Flush doors will be entirely smooth on both sides. This can be great for a modern look, with either quality veneers or painted finishes. Flush interior doors are a popular choice in many different environments.

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Panelled Internal Doors

Coming in a wide range of looks, panelled internal doors will have square or rectangular patterns. These will be either hollow or solid doors and can range from single panels to options like cottage doors with long thin panels, and four or six-panel doors. Panelled looks can look completely at home in both traditional and modern buildings.

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Internal Glazed Doors

Including a glazed panel in an internal door can make for a great modern look in a home. These can be designed as panelled doors where the upper panel is glass, or around long glazed panels reaching vertically across the whole door. These will help light to move through a building.

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Should You Paint Interior Doors?

This will be up to you; many hollow and solid doors offer a great-looking veneered finish, allowing them to be used as-is. Painting doors can help them to blend within an environment or stand out from it. Some choose to make their doors bold by utilising glossier paints, which will provide a reflective counterpoint to matt walls.

What are the Standard UK Sizes of Internal Doors?

The most popular door size within the UK is 762mm x 1981mm, but this is by no means standard and you will find a range of different sizes within UK homes and commercial properties. While these other sizes with all be fairly comparable, this means that when shopping for doors for your project, you should first measure the size of the space, to ensure you know what size of door is needed.

Quality Internal Doors for Sale

Building Materials Nationwide are the one-stop shop for professionals, working across the industry to supply tradespeople with the products they need. If you’re looking for internal doors for the inside of a building project we have a huge range of interior door options on our website, with glazed doors, bi-fold doors, and sliding doors available. We also have a separate section of office doors, alongside door handles and hinges. All of these can be delivered across the UK. For customers within the industry, we also offer trade accounts, granting access to competitive trade pricing and the services of a dedicated account manager who’ll be able to source any products you need through our network of suppliers.

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