How Long Does a Loft Conversion Take?

If you’re thinking about transforming your unused loft area into a functional space, one of the first questions you might have is: how long does it take for a loft conversion to be completed?

The short answer is around 8 weeks on average for the build itself.

This is an average and depending on the type of conversion, planning requirements, and design complexity, the full process from initial consultation to completion can vary. In this guide, we’ll break down the average durations for different loft types, the factors that can alter the loft conversion timeline and what you can expect week by week.

Types of Loft Conversions & Their Timelines

Not all loft conversions are created equal, and some can be completed quicker than others, depending on the structural changes needed. Below is a list of the most popular types of loft conversion and their estimated average timelines.

How Long Does a Dormer Loft Conversion Take?

There are different types of dormer loft conversions, but each extend your existing roof vertically to create extra headroom and floor space. They’re one of the most popular choices and typically take 6–8 weeks to complete once construction begins. Below are the average timeframes for each type of dormer conversion.

Rear Dormer: The most common option, built onto the back of your property. A rear dormer loft conversion is usually completed within 6–8 weeks.
Side Dormer: Similar to a rear dormer, but on the side of the property. A side dormer loft conversion also has an average timeline of around 6-8 weeks for completion.
L-Shaped Dormer: Combines two dormers at right angles for maximum space, often used in period properties. L-shaped dormer loft conversions take around 8–10 weeks due to the more complex structure.
Pitched Roof Dormer: Features a sloped roof that blends seamlessly with your existing property. The average time for a pitched dormer loft conversion to be completed is 6–8 weeks.

man walking across loft conversion in front of dormer windows

How Long Does a Mansard Loft Conversion Take?

A Mansard loft conversion involves replacing one or both roof slopes with a near-vertical wall and a flat roof on top. This creates a huge amount of space but requires more structural work than a standard dormer conversion. Expect around 8–10 weeks for completion.

How Long Does a Velux Loft Conversion Take

The quickest option, a Velux loft conversion (also known as a rooflight loft conversion) use your existing roofline, adding roof windows without altering the structure. They can be completed in as little as 4–6 weeks, making them ideal if you want minimal disruption and you don’t require masses of extra space.

How Long Does a Hip-to-Gable Loft Conversion Take?

A Hip-to-Gable loft conversion involves extending the sloping side of your roof (hip) into a vertical wall (gable), often paired with a rear dormer for extra space. Completion usually takes 8–10 weeks.

How Long Does a Piggyback Loft Conversion Take?

Piggyback loft conversions (also referred to as a roof lift loft conversion) is where the ridge height of your roof is raised to create headroom. It’s a major structural change, so expect around 8–10 weeks before this type of conversion is completed.

Key Factors That Affect a Loft Conversion Timeframe

Even with an average of around 8 weeks for completion, several factors can influence the overall timeline:

Type of Conversion

As seen above, Velux conversions are often the quickest conversion to complete, while Mansard, L-Shaped Dormer, Hip-to-Gable and Piggyback conversions will usually take longer due to their complexity and/or required structural changes.

Planning Permission & Building Regulations

Many loft conversions fall under permitted development rights but knowing if you require planning permission is a crucial step in the planning phase. Complex designs or properties in conservation areas may require planning permission and building regulations approval is essential, which runs alongside the build process.

So, how long does planning permission take for a loft conversion? It can vary between local planning authorities (LPA), but it can take around 8–12 weeks on average for a decision.

Design Complexity

If your loft conversion involves bespoke layouts, unusual roof shapes, or intricate finishes, this will naturally add time to project.

Features & Finishes

Adding features such as ensuite bathrooms, built-in storage, or luxury finishes can extend the build by 1–2 weeks on average depending on the exact specification and requirements.

Weather & Access

Poor weather can slow progress, particularly during exterior and roof works. Restricted access to your property can also add extra time.

What to Expect Week by Week

As highlighted already, different loft types and various scenarios will alter the loft conversion process. Below is a rough guide on how a standard dormer loft conversion with The Loft Room might progress.

Weeks 1–2: Preparation & Structure

Scaffolding erected and delivery or timbers and steels
Dormer frame constructed
Building of internal walls
Joists and floor structure laid

Weeks 3–4: Internal Works

Carry out first fix electrics and plumbing
Lay flooring and install insulation
Plaster boarding carried out
New staircase installation

Weeks 5–6: Roofing and Internal Works Continued

Plastering and roofing works
Second fix carpentry
Second fix electrics and plumbing

Weeks 7–8: Finishing Touches

Final quality-control check
Clean inside and out
Removal of scaffolding
Final decoration and snagging

For more complex conversions (e.g., L-shaped dormers or Mansards), expect additional time in the structural and finishing phases.

Summary

So, how long does it take to do a loft conversion?

Average build time: Around 8 weeks
Velux conversions: 4–6 weeks (estimated)
Standard dormer conversions: 6-8 weeks (estimated)
Larger structural projects: 8-10 weeks (estimated)

The key is to factor in design, planning, and preparation time on top of the construction schedule. At The Loft Room, we will consult with you from day one to ensure a smooth process and that realistic timelines are provided. We’ll advise on how to get the best out of your conversion based on your requirements, manage the process of getting planning permission for you if needed, and work together on the design and finish for a stunning end result that transforms your home.

If you’re ready to start planning your dream loft, get in touch today for a free consultation and quote.

Get in touch for a free no obligation quote

      EXCELLENT  
   Based on 403 reviews 
    
 
 
 
   
 
 
      Posted on Google  
   
   Henry 
 6 October 2026
 
 
  We recently had a rear dormer completed by The Loft Room, which also involved lowering the ceilings throughout the first floor.

The efficiency and quality of the work carried out are the main reasons we’ve given five stars. We felt the administrative and communications side of the process could have been better, but ultimately the most important thing for us was the quality of the build, and in that respect we were extremely happy.

The team on site were excellent and always treated the house as our home rather than simply a building site. They were respectful, tidy and a pleasure to have around throughout the project.

Dragos has been a joy to work with and brought a huge amount of calm, experience and knowledge to the project. Lulian, on site, was the ultimate professional. Nothing was ever too much trouble, and the quality of his workmanship was excellent.

Overall, we’re really pleased with the end result and wouldn’t hesitate to recommend The Loft Room based on the quality of the work and the team we had on site.
  
 
     Posted on Google  
   
   Ruth Gibbons O'Brien 
 2 October 2026
 
 
  We are so happy with our new loft space and have been really impressed with The Loft Room from start to finish.

Communication throughout the project has been excellent. Marius and his team worked incredibly hard to meet deadlines while taking great care and pride in their work. Helen in the office, along with Marius, were always on hand to keep us updated on progress and talk us through the different choices and options available.

It was also really helpful having a clear contract in place detailing exactly what was included in the agreed costs. This made budgeting much easier and meant there were no unexpected or surprise costs along the way.

We can’t wait for the final touches to be completed so we can start enjoying our family’s new space. Thank you to the whole team for all your hard work — we’re really happy with the result!
  
 
     Posted on Google  
   
   Alex Moon 
 28 September 2026
 
 
  The loft room team were great. John was very respectful, and kept us informed on progress. Going the extra mile to make our new space amazing. They really managed to maximise the floor space to create a great sized master bed and en-suite.
  
 
     Posted on Google  
   
   Calum Millar 
 26 September 2026
 
 
  Recently had a dormer loft conversion completed by Ash and Alfie of The Loftroom.

From design all the way through to finishing the construction the team have been great. Quality of the work is outstanding, kept informed and updated all throughout the build, and always consulted about the specifics.

Highly recommend.
  
 
     Posted on Google  
   
   Chris Talbot 
 25 September 2026
 
 
  We are delighted with our new loft conversion by The Loft Room. The whole process went incredibly smoothly, from the planning stage all the way through to decorating.

A huge thank you to Vio, who led the team on our project. Vio and the team’s hard work and dedication has transformed our house. Vio kept everything running on track, maintained a high standard of work, and was always a pleasure to deal with. He and his team treated our home with respect and made sure the details were done right. And also, a special mention to all in the office whose excellent communication kept us in the loop throughout.

We would heartily recommend The Loft Room to anyone looking to do a loft conversion. Thanks guys!
  
 
     Posted on Google  
   
   Sarah Lister 
 22 September 2026
 
 
  We are delighted with our new loft space! Our team leader, Mihai, was fantastic and kept us informed about progress throughout. Everyone who came to work on the space was friendly and communicative, and gave us advice about what might work best.
Together, the team created a superb space with two bedrooms and a bathroom which are all spacious and finished to a very high standard. Mihai took time to make sure that everything was finished as we wanted it to be and went the extra mile to ensure downstairs where they had broken through was finished and integrated with the existing decor.
The office team at The Loft Room were very helpful in keeping us up to date and checking in to make sure that we were happy with how everything was going. It made such a difference using a company who do loft conversions day in day out as it meant that everything ran smoothly, the project was managed for us and the build ran to the time scale presented to us from the start.
We would highly recommend The Loft Room to anyone who is thinking about creating a new space.
  
 
     Posted on Google  
   
   Simon Newell 
 15 September 2026
 
 
  We honestly couldn't recommend The Loft Room highly enough.

Our relationship with them actually started around three years ago when they first came out to quote for our loft conversion. We weren't ready to go ahead at the time, but when we finally decided to push the button this year, The Loft Room were still the company we wanted to use – and we're incredibly pleased that we did.

This was a significant project, creating an entirely new top floor with two bedrooms and two en-suites, all while we continued living in the house as a large family.

From the very beginning, The Loft Room had a genuinely friendly, family-company feel. Everyone we dealt with seemed to care about the project and about making sure we were happy, and they were very conscious throughout that this wasn't just a building site – it was still our family home.

A very special mention has to go to Jamie and Jared, who carried out the build. They were absolutely fantastic. They worked incredibly hard, were friendly, considerate and easy to have around, and we built a really good relationship with them over the course of the project.

Jamie's workmanship and experience were obvious from the start. He constantly kept us involved, asked questions rather than making assumptions and made sure we were happy with how things were progressing. Communication was excellent throughout.

With any building project of this size there are inevitably going to be challenges, changes or occasional delays. For us, the important thing was how these were dealt with. Jamie was always upfront, explained what was happening and kept us updated, so there were never any nasty surprises. If something needed sorting, it was sorted.

That made a huge difference, particularly as I work from home and we were living through the entire build as a family. Jamie and Gared were incredibly respectful of that and did everything they could to minimise the disruption.

Most importantly, we absolutely love what they've created. Turning what was previously unused loft space into two fantastic bedrooms and two en-suites has completely transformed the house. The quality of the workmanship is excellent and, looking at the finished result, we feel we've had really good value for what was a major investment in our home.

It probably says everything about our experience that after months of having Jamie and Jared here every day, we actually miss having them around! I work from home, so it's genuinely strange not having the daily chats anymore.

A really positive experience from the first conversation three years ago right through to completion. We'd happily recommend The Loft Room to anyone considering a loft conversion.

A huge thank you to the whole team – and particularly Jamie and Jared – for everything you've done for us.
  
 
     Posted on Google  
   
   Ben Chadwick 
 22 August 2026
 
 
  We have just had our loft completed by the loft room. They were really easy to work with, took care of all the paperwork. They were great at communicating all the stages and their response time was excellent. Adrian was our builder and he was fantastic. Super thorough, reliable, fast, tidy and often gave us suggestions when we were unsure. The whole project was finished in about 6weeks! We wouldn’t hesitate to recommend The Loft Room to anyone. Many thanks!
  
 
     Posted on Google  
   
   Ken O'Neill 
 19 August 2026
 
 
  We are so happy we decided to go ahead with The Loft Room. Everyone we met from our initial consultation with Paul to Lulian and his team and Helen and Melissa in the office have been great. We were especially impressed with the hard work of Lulian and his team even through the heatwave. They were friendly and professional and always ready to answer any questions we had. Thanks to Lulian for suggesting bigger Velux windows - they are amazing! All the trades involved were great - we will definitely use them again in the future. The work was completed on time and we are really happy with it. We would certainly recommend The Loft Room.

See all Google reviews