What is a Dormer Extension?

A dormer is a roof extension that creates additional headroom and usable space in your loft. It typically involves building a vertical wall from the roof slope and adding a flat or pitched roof on top.

Dormers are commonly built at the rear of a property and are often used to create a new bedroom, office or bathroom in the loft.

What is Permitted Development (PD)?

Permitted Development is a national set of planning rules that allow homeowners to make certain types of extensions and alterations without needing full planning permission.

A dormer can fall under PD if it meets specific size, height, and position rules. We will advise you clearly if your proposed dormer qualifies.

What does the process involve?

1. Measured Survey

We visit your home to accurately record the layout, structure, and roof dimensions.

2. Concept Design

We design a dormer that maximises space while complying with PD limits. We’ll also advise on internal layout, stair access, and headroom.

3. Lawful Development Certificate (optional but recommended)

While not legally required, we strongly recommend applying for a Lawful Development Certificate to prove your dormer was built lawfully under PD rules. This protects your future resale or remortgage.

4. Building Regulations Drawings

Dormers must comply with Building Regulations—especially structure, insulation, fire escape, and drainage. We prepare a detailed set of drawings for Building Control and your builder.

What are the benefits of a dormer under PD?

• No formal planning application needed
• Faster start on site
• Extra space and added value without changing the footprint
  

  

What are the risks or things to watch out for?

• Your dormer must not exceed 40m3 (terraced) or 50m3 (semi-detached/detached) including any previous roof extensions.
• It be lower than the highest part of the existing roof – usually the ridge.
• It must be set back at least 200mm from the eaves.
• You can’t add balconies, raised platforms or alter the front roof slope under PD.
• Article 4 Direction areas remove PD rights—you’ll need to check with your council.
• Loft conversions are NOT permitted development for houses on designated land.

We’ll confirm all of this before you commit.

Do I need a builder or a project manager?

We provide the design, compliance and technical documentation. You’re free to appoint your own builder or we can refer trusted contractors. For more involved projects, we can act as Principal Designer t

o help manage compliance and reduce risk.

How long will it take?

Typical timeline:

• Survey to final design: 2–3 weeks
• Lawful Development Certificate (if applied): 8 weeks
• Building Regulations approval: 1–2 weeks
• On-site works: Usually 4–6 weeks depending on builder and scope

Summary

Building a dormer under Permitted Development is one of the quickest and most cost-effective ways to unlock your loft’s potential.

At Studio Tashkeel, we make sure it’s designed smartly, drawn accurately, and built legally—so you can extend with confidence.

From roof to room—done right.

 

🚀 Ready to Take the Next Step with Your Property?

Whether you’re exploring an extension, planning a new project, or just want expert insight before making a move — we’ve made it easy to get started.

✅ 1. Want to Create Something New with Your Property?

If you’ve got ideas and want to explore possibilities with an expert, book a FREE 15-minute Discovery Call with our team:
🔗 Book Your Call Now

🏠 2. Planning a Home Extension?

Don’t speak to a builder just yet — download our Starter Pack with the 7 essential questions every homeowner should ask before starting.
🎁 Get the Starter Pack Here

📋 3. Ready to Begin Your Project?

If you’re ready to start the process and want to work with Studio Tashkeel, begin by filling out our quick Client Onboarding Form:
📝 Start Your Project Now

🌐 Explore More:

Visit our website for case studies, services, and inspiration:
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Final Tip: Before committing to any loft extension, confirm that your design meets PD criteria and local council conditions—this ensures faster approvals and greater resale confidence.