Your guide to London

Loft Conversion costs in 2021

The price of a loft conversion is understandably a crucial factor in deciding whether or not to embark on such a project. At Visionary Lofts we appreciate this, and in this guide, we’ll be discussing the typical costs associated with getting a South London loft conversion, as well as giving you a general idea of what’s involved.

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Visionary Lofts

London Loft Conversion

In 2021, the cost of a loft conversions in London is generally between depending on the nature of the design, level of project management, and type of conversion being built.

Aside from the general costs, it’s worth remembering that not every quote is calculated in the same way, and things included by one company might be considered as extras by another. Find out about the potential hidden costs that could trip you up and seriously dent your budget if you don’t plan for them in the following video.

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Main costs for a South London loft conversion

As we said, the type (or style) of loft conversion you have built can affect the costs involved. In our estimates below, we have factored in what we consider to be the ‘core’ costs and are inclusive of VAT. Core costs exclude any tiling, decoration, carpets or other flooring.

You can read about the different styles or types of loft conversions by clicking on the conversion name.

2d image of dormer loft conversion

Dormer conversion

Estimate Cost: £40k

2d image of L shaped dormer Visionary Lofts

L-Shape Dormer Conversion

Estimate Cost: £49k

2d image of hip to gable before converting a hip to gable roof Hip to Gable Loft Conversion

Hip to Gable Conversion

Estimate Cost: £46k

2d image of Mansard loft conversion

Mansard Conversion

Estimate Cost: £48k

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Getting a Visionary Lofts conversion
for your South London property

At Visionary Lofts, we take as much of the guesswork as possible out of the costs for converting your loft space. We achieve this by providing all of our customers with a free initial site visit that includes a survey of your property to obtain all the measurements and aspects of your home and your loft space (access permitting) that enable us to put together a quote.

As with any build work, it’s important to remember that there could be unforeseen incidents or issues that add to the overall costs involved, and we always recommend having a contingency budget in excess of 10% of the total value of your project in place.

Once we’ve quote for the core cost of your loft conversion, we can also provide some quotes for any additional works you’d like us to organise for you. See examples of what some of these costs might be below:

Factors that influence the cost of a loft conversion

In order to determine the average costs involved in building a loft conversion, it’s important to identify and consider the many factors that can affect the overall price. While not all of the factors in the list below will be relevant to everyone, it can pay dividends to do due diligence now so you’re not caught out by unexpected costs.

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Key factors to consider:

1. Freeholder / Leaseholder status

You might want to investigate whether you own the loft space, or if you need to purchase the loft space from a freeholder or secure permission to carry out the loft conversion.

2. Party Wall Matters

You will need to determine if you’ll need party wall surveys and subsequent party wall agreements. You can read about party wall agreements in our FAQs

3. Loft size

You might want to think about if you want or need to convert all of your available loft space.

4. Loft suitability

You will need to know if your loft needs to be strengthened or head height added in order to facilitate a loft conversion.

5. Extra Features

You’ll need to think about if you want extra features, such as skylights, underfloor heating, or a wet room.

6. Fire Regulations

You’ll want to find out if the rest of your house complies with fire regulations, or if this needs to be addressed. You may also need to budget for fire doors, alarms and even a sprinkler system!

7. Site Access / Logistics

You’ll need to know and plan how your roof will accessed during construction; accessibility issues will affect the cost of parking, waste removal, materials storage and scaffolding.

8. The Type of Loft Conversion

The type or style of loft conversion is usually determined by your property type, and you can find out more in our guide on the various types of loft conversions available in South London

9. Type of Contractor

Finally, you might want to think about who you trust to have working in your home and their level of expertise in managing a loft conversion. A general builder might appear cheaper on paper, but a loft conversion specialist will have the necessary expertise to deliver a quality-built loft conversion that adheres to all the fire and building regulations.

There’s more to a loft conversion project than the costs.

Project management and the ability to deliver to deadlines are two other important factors that you will want to take into consideration when planning your loft conversion.

Timescales and typical schedule

The timescale of your South London loft conversion can be split into two phases: the first being the initial planning of the project, and the second being the actual time it takes to build it.

Although our timescales below are estimates, we know how useful it can be to have some indication of the duration of any building work. The schedule detailed below is an example of the how long a standard loft conversion can take to complete.

Typical Schedule

Weeks 1 - 2

Week 1 will be the preparation stage, which consists of the site set-up any demolition works are carried out. This can also include erecting of any scaffolding and the delivery of a skip if necessary.

By Week 2, the existing roof structure will be stripped out and new structural steel work installed.

During these first weeks, the vast majority of work carried out will be external, and you should experience minimal disruption to your home from the inside.


Weeks 3 - 6

Over the course of several weeks, construction activity will begin to move to your interior. Access to your roof will be required, and this should allow disruption within your home to be kept to a minimum.

Next, the timber structure, staircase and glazing will be installed. This will be closely followed by any internal stud walls, and the 1st fix for services should be completed by the end of week 6.


Weeks 7 - 12

During this period, insulation to your loft space and plaster boarding will be installed. Once the plastering is completed, any carpentry and joinery, electrics and plumbing will be finished.

Finally, work on the finishing touches of your loft conversion, such as painting and decorating, tiling and flooring will begin.

At week 12, your loft conversion should be completed and signed off.



83 Tivoli Road,
West Norwood,
London SE27 0EE


020 3536 8734