Top 7 Reasons to Start Using Single Directory Components (SDCs) in Drupal Today

1. Everything in One Place – No More File Hunting

Traditionally, creating a Drupal component required:

• A .twig file in the templates folder
• A .yml file in config/schema or *.libraries.yml
• CSS in a css/ folder
• JS in a js/ folder

This often forced developers to jump around the theme directory to track down related files.

With SDCs:
 Each component has its own folder, containing:

• component.twig → Markup
• component.yml → Metadata & props
• component.css → Styles
• component.js → Behavior

Everything is grouped neatly, just like in modern frameworks such as React or Vue.

Example:

/components 
 /button 
    button.twig 
    button.yml 
    button.css 
    button.js 

Inside button.yml:

name: Button
status: stable
description: "..."
props:
properties:
type: object
 btn_text:
  type: string
  required: true
 url:
  type: string
  required: false

Inside button.twig:

<a href="{{ url|default('#') }}" class="btn">
{{ btn_text }}
</a>

2. Cleaner, Reusable Code

Because each SDC is modular, you can reuse the same component anywhere in your Drupal project. Need a button on a landing page, card in a blog listing, or modal in a form? Just call the component.
Example usage in a template:

{% include '@components/button/button.twig' with {
btn_text: 'Read More',
url: '/about'
} %}

This prevents duplication, making your theme DRY (Don’t Repeat Yourself).

3. Easier Collaboration for Teams

In big projects, different developers often step on each other’s toes when editing shared templates. With SDCs, each component is isolated, so:

• A designer can focus on CSS in button.css
• A front-end dev can tweak Twig markup
• A back-end dev can adjust YAML props

  Everyone works in their own component folder, reducing conflicts.

4. Better Maintainability and Scalability

When your site grows, traditional theming can become overwhelming with hundreds of templates and style files scattered around.
With SDCs:

• You can quickly locate a component folder
• Deleting or updating a component is as simple as managing its single directory
• Adding new features is more structured

Think of it as Lego for Drupal theming: easy to assemble, scale, or remove pieces.

5. Consistent Styling with Tailwind CSS

SDCs work perfectly with modern styling tools like Tailwind CSS. Each component can ship with its own Tailwind utility classes or scoped styles in its .css file.
Example:

 button.css
.btn {
@apply px-4 py-2 rounded-lg bg-blue-600 text-white hover:bg-blue-700 transition;
}

This makes sure your design system stays consistent and professional across the site.

6. Improved Developer Experience

With SDCs, onboarding new developers becomes much easier:

• Instead of learning a messy folder structure, they just explore /components.
• Each component is self-documented via its .yml file, describing props and usage.
• Debugging is faster since everything related to one component lives in a single place.
   

This means less frustration and faster development cycles.

7. Foundation for a Design System

SDCs aren’t just about code organization; they’re about building a reusable design library.
For example, you can start small with:

• button (basic action element)
• card (content container)
• modal (overlay interaction)
   

And scale it into a component library that your entire team (or multiple projects) can reuse.

Card Example:

card.yml
name: Card
status : stable
description : this is the card component 
props:
  properties:
  type: object
title: 
  title: Title
  description: Title of the Card
  type: string
description: 
  title: Description
  description: description of the Card
  type: string
image:
  title: Image
  description: Image of the Card
  type: string
link:
  title: Link
  description: Link or CTA of the Card
  type: string
 	  
card.twig
<div class="card shadow-lg rounded-lg overflow-hidden">
<img src="{{ image }}" alt="{{ title }}" class="w-full h-48 object-cover">
<div class="p-4">
  <h3 class="text-lg font-semibold">{{ title }}</h3>
  <p class="text-gray-600">{{ description }}</p>
  <a href="{{ link }}" class="btn mt-2">Learn More</a>
</div>
</div>

This way, your Drupal theme evolves into a design system, where developers and designers speak the same language.

Final Thoughts

Single Directory Components (SDCs) are not just a convenience — they’re a game-changer for Drupal theming. They simplify workflows, promote reusability, and help build scalable, future-ready projects.

If you’re starting a new Drupal project today, make SDCs your default approach. And if you’re maintaining an old theme, consider migrating piece by piece.
By adopting SDCs, you’ll:

• Save time
• Reduce bugs
• Improve collaboration
• Build a maintainable design system
   

The future of Drupal theming is component-based — and SDCs are leading the way.