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.
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.