Top 10 Questions London Homeowners Ask Before a Loft Conversion

We’ve gathered the top 10 most common queries we hear from homeowners across London – along with clear, honest answers to help you feel confident about the process.

1. Do I need planning permission for a loft conversion?

In many cases, no, but it depends. Most loft conversions fall under permitted development rights, meaning you won’t need planning permission. However, if:

• Your home is in a conservation area (e.g. parts of Camden, Islington or Richmond)
• You’re increasing the roof height or shape
• You live in a flat or maisonette

…you may need to apply. It’s always smart to check with your local planning department or hire a company who will handle this for you.

2. How much does a loft conversion cost in London?

Costs vary depending on the type of conversion, the size of your property, and the spec of your finishes. As a rough guide:

• Velux (rooflight) conversion: from £30,000+
• Dormer conversion: £45,000–£60,000
• Hip-to-gable: £50,000–£65,000
• Mansard conversion: £60,000–£80,000+

These are average estimates. The final cost will depend on your layout, plumbing/electrical requirements, finishes, and structural complexity.

3. What type of loft conversion is best for my property?

The answer depends on your house style and goals. Here’s a quick breakdown:

• Terraced house: Dormer or mansard
• Semi-detached: Hip-to-gable + dormer
• Detached: Most options are possible
• Bungalow: Dormer or full-width dormer
• Flat/maisonette: May require freeholder permission + planning

Marken Lofts will assess your home and recommend what’s structurally and legally possible.

4. Will a loft conversion add value to my property?

Yes – typically 20–25%, depending on the size and quality of the conversion. A well-designed loft can add an extra bedroom, en-suite, or even a home office, all of which boost resale value, especially in areas like Clapham, Hackney, or Chiswick.

5. How long does a loft conversion take?

Here’s a rough timeline:

• Design & planning: 1-2 weeks
• Party wall agreements (if needed): 2-6 weeks
• Build phase: 6-8 weeks

So in total, you’re looking at around 2-3 months from initial consultation to completion – though simpler conversions can be quicker.

6. Do I need a party wall agreement with my neighbours?

If your conversion work affects a shared wall (which it often does), you’ll need to serve a party wall notice to your neighbours. If they consent, great. If not, you may need to appoint a surveyor and draw up a party wall agreement. It’s best to do this early to avoid delays.

7. Will I need to move out during the build?

In most cases, no. Builders usually work from scaffolding through the roof, so disruption is minimal for most of the project. There may be a few days toward the end when builders access the main house, but it’s usually manageable if you’re living in.

8. Can I add a bathroom to my loft conversion?

Absolutely. An en-suite is one of the most popular features in a London loft conversion. Just keep in mind:

• Plumbing access (especially soil pipe routes)
• Ceiling height for showers
• Good ventilation

Adding a bathroom will increase cost, but also adds huge value.

9. How do I choose the right loft conversion company?

Marken Lofts are a family run company with over 30 years practical experience.

• Experience working across London. See what areas we cover here.
• Architectural support and planning knowledge
• Accreditations – We are accredited by the Federation of Master Builders.
• Transparent & competitive pricing
• Free, no-obligation design consultations
• Recent projects or reviews – See what our clients are saying about us here.

10. Will a loft conversion affect my council tax or insurance?

• Council Tax: Usually stays the same – unless the home’s value moves up a whole band, which is rare.
• Home Insurance: Yes – you must inform your provider of the extra room(s) to ensure full cover.

Final Thoughts

A loft conversion is one of the best ways to future-proof your London home, adding space, style, and value. But like any major project, it comes with questions.

Got more? We’re happy to help. Whether you’re just exploring or ready to start designing your dream loft, our team is here to guide you every step of the way.

Want expert advice on your property?
Book a free consultation today and let’s explore the possibilities for your loft. Fill out the form on this page and we will be in touch, or call now on 0800 111 4883.