Wood door glossary

Last Updated: 5 September 2022

Doors Infographic


This is where wood, specifically Accoya® wood, is subjected to a vinegar, which turns it into a hardwood by preventing the cells in the wood from being able to absorb water.


Accoya® wood is a genetically modified European Redwood, which is a softwood. Modified via a process called acetylation, this gives Accoya properties that are traditionally associated with hardwoods. These include incredible durability and strength along with excellent natural insulation.

Because of this outstanding durability, Accoya doors come with a 50-year warranty and an expected lifespan of around 80 years. Accoya is also one of the most eco-friendly building materials available.

Bifold Doors

Bifold doors are a modern patio door style consisting of several glazing panels. When opened, the panels fold to one side and stack on top of one another, leaving a wide aperture. They are also referred to as bi-folding doors.

C2C Certification

Cradle to Cradle (C2C) Certification is a global recognized measure of sustainable products that are made for the circular economy. To achieve certification under this scheme, a material is assessed at must excel in terms of:

  • Material health
  • Material recycling
  • Renewable energy and carbon management
  • Water management and social responsibility

Accoya® wood has a C2C Gold and C2C Platinum (Material Health) certification, giving you an indication of the environmental benefits on offer.

Door panel

The door panel refers to the whole part of the door that sits between the frame and swings back and forth. Also referred to as a ‘slab’, it’s common for door panels to be divided up into smaller panels, which are set between the stiles, rails and mullions.

French Doors

French doors consist of 2 inward or outward opening, largely glazed doors that sit side by side. Their design originated in France during the 16th century and they are a classic solution for allowing light and air into a property.

FSC® Certified

FSC® stands for the Forest Stewardship Council, which is a non-profit organisation that promotes responsible forestry. Any products that are FSC® Certified have successfully demonstrated that they are made with, or contain, materials from sustainable and responsibly sourced timbers.

The Accoya timber that we use is FSC® Certified.

Hardwood Doors

There are two types of woods used to make timber doors: hardwoods and softwoods. What defines a hardwood from a softwood is the presence of special pores in the cellular structure of the wood, which makes hardwoods denser.

Typically, but not always, hardwoods are more durable, stronger and offer better weather resistance than softwoods, so they are great for external applications, including doors.

Here at Reddish Joinery, our hardwood timber doors are constructed from Oak.


Joinery is the process of creating wooden items by ‘joining’ different pieces of wood together. Along with doors, joinery is used to create everything from windows to pieces of furniture.

Learn the difference between joinery and carpentry


When two windows are joined together, or a window and a door are joined, the seam that sits between the frames of each unit is called the mullion.

On panel doors, mullions separate two panels and they are located in the vertical part in the middle of the door.

Multipoint locks

Multipoint locks are a type of locking system which secures a door to the frame at multiple points. This means that there are no weak points available for would-be intruders to apply to and force the door open. They are engaged and disengaged via the turn of a key.

Here at Reddish Joinery, our Accoya front doors are fitted with multipoint locks as standard.

PEFC™ Certified

The Programme for the Endorsement of Forest Certification is a non-profit organization that promotes sustainable forest management through third party certification. Any products with PEFC™ certification, such as our Accoya doors, is an indication that they come from sustainably managed forests.

Period home

The term period home is a general term to describe properties from a historical period. The historical eras that this usually refers to are the Victorian, Georgian and Edwardian periods.

As timber is a traditional building material, renowned for its classic charm, timber doors make the perfect addition to any period homes.


Rails is the term used to describe the narrow horizontal segments that you find on a door panel.

Softwood Doors

Softwoods come from gymnosperm trees, which do not have pores. So, to produce sap and transport water, they rely on medullary rays and tracheids, which gives softwoods lower density. The lack of pores is what distinguishes a softwood from a hardwood.

Typically, softwoods are easier to source, cheaper to produce and more sustainable than hardwoods, but they also require more maintenance and are not as durable.

The only softwood we use here at Reddish Joinery is Accoya. However, Accoya has been genetically modified to provide characteristics that are typical of hardwoods.


Sidelights are tall, narrow windows located on one, or both, sides of a door. A great way to increase the amount of natural light coming inside, they can be customised with a wide range of glass types and designs.


A stile is the term to describe the narrow vertical segments that you can on either side of a door panel. The one on door lock side is called the lock stile, whilst the other is called the hinge stile.


A transom is a narrow window that sits above a door or window. They are usually fixed in place, particularly when used with a door. On a door, transom windows might also be referred to as a toplight.


The term woodgrain is used to describe the pattern that you find running lengthwise on a piece of wood. This pattern differs amongst different types of timber and even within the same type of timber. It also helps to give wood its natural appeal

Wood stain

Wood stain is a type of paint that is used to colour wood. Along with changing the wood’s appearance, staining also preserves the wood’s appearance and protects it against rotting, UV rays and moisture.

Our wooden doors are available with a variety of wood stains, so you can create several looks for them.

For further information on wooden doors, get in touch with Reddish Joinery today. We are available to call on 0161 969 7474 or you can contact us online.

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