If you’re thinking about converting your loft, one of the first questions that comes to mind is how long the whole thing is going to take. It’s a fair question. Nobody wants a building project dragging on for months with no end in sight, and knowing what to expect from the start makes the whole experience a lot less stressful.
The honest answer is that it depends on the type of conversion. But as a general guide, most loft conversions take between six and ten weeks from the day work starts on site. Here’s how that breaks down.
Before Work Starts
The timeline doesn’t begin when the scaffolding goes up. There’s a preparation phase that happens before any physical work starts, and it’s worth factoring this into your planning.
Once you’ve had your free survey and accepted a quote, the next step is getting your building regulations application submitted and approved. This is a legal requirement for all structural loft conversions and covers things like structural integrity, fire safety, insulation and means of escape. At ST Lofts we handle this on your behalf, but it does take a few weeks to process.
If your conversion requires planning permission, such as a mansard or certain types of dormer in a conservation area, you’ll need to factor in the planning application process too. Standard planning applications typically take eight weeks to be determined by the local authority.
Once all approvals are in place, materials are ordered and your start date is confirmed, the physical build can begin.
Week 1 to 2: Structural Work and Roofing
The first stage of any loft conversion involves the structural work. This is where the existing roof structure is strengthened or altered to accommodate the new space. For a dormer conversion, the opening in the roof is created and the dormer structure is built out. For a hip-to-gable, the roof shape itself is changed. For a Velux conversion, this phase is considerably simpler as the roof structure stays largely intact.
Scaffolding is erected before work begins and remains in place until the roof is weathertight. This phase can feel a little dramatic from the outside, but it moves quickly with an experienced team.
Week 2 to 4: First Fix
Once the structural work is complete and the roof is weathertight, the internal work begins. First fix covers the structural floor joists, the staircase installation, and the first fix electrics and plumbing if an en suite is being added.
This is also the stage where the dormer or new roof windows are made fully weathertight and insulation is installed between the rafters. The scaffolding usually comes down towards the end of this phase.
Week 4 to 7: Second Fix and Plastering
With first fix complete, the walls and ceilings are boarded out and plastered. This is the stage where the room really starts to take shape and you can properly visualise what the finished space is going to look like.
Second fix electrics and plumbing follow once the plaster is dry, covering sockets, switches, lighting and any bathroom fittings. Joinery work such as doors, skirting boards and window boards is also completed during this phase.
Week 7 to 10: Finishing
The final phase covers decorating, flooring and any fitted elements such as wardrobes or bespoke storage. This is also when the final building regulations inspection takes place, confirming the work meets all required standards and issuing your completion certificate.
Once that certificate is in hand, your new room is ready to use.
What Can Slow a Loft Conversion Down?
Most projects run to schedule, but a few things can extend the timeline. Unexpected structural issues discovered once work begins, delays in planning or building regulations approval, and bespoke or specialist materials with longer lead times can all add time to a project.
The best way to avoid surprises is to choose a specialist company that carries out a thorough survey before quoting. At ST Lofts, our free surveys are designed to identify potential issues before work starts, so your timeline is as accurate as possible from day one.
How Long Will My Loft Conversion Take?
As a quick guide:
Velux / Roof Light Conversion: 6 to 8 weeks on site
Dormer Conversion: 8 to 10 weeks on site
Hip-to-Gable Conversion: 8 to 12 weeks on site
Mansard Conversion: 10 to 14 weeks on site
These timelines cover the physical build only and don’t include the pre-build preparation phase. Your ST Lofts project manager will give you a full end-to-end timeline at the survey stage.
Frequently Asked Questions
Do I need to move out during a loft conversion?
No. In the vast majority of cases you can continue living in your home throughout the build. Most of the work takes place at roof level and our team works carefully to minimise disruption to the rest of your house.
When is the most disruptive part of a loft conversion?
The first week or two tends to be the noisiest and most disruptive, when the structural and roofing work is taking place. After that the build becomes progressively quieter and less intrusive.
Will the project definitely finish on time?
We give realistic timelines from the outset and our project managers keep your build on track throughout. Unexpected structural issues can occasionally cause delays, but these are identified and communicated to you as early as possible.
Does a loft conversion need a completion certificate?
Yes. A completion certificate is issued by building control once the work has been inspected and signed off. You’ll need this document if you ever sell your home, so it’s important to ensure it’s obtained at the end of every project. ST Lofts manages this as part of every build.
