Bush Builders

Cost of a Loft Conversion 2018

Want to know what a loft conversion will cost in 2018? This guide covers the various options and what you can expect to pay.



Professional Fees

Roof Types


Mansard conversions

Basic loft conversion price

Dormer roofing price

Structural and Roofing Changes

The cost of a loft conversion can provide an excellent way to increase the space in your home and offer a cost-effective method of improving the value of your home.

There are many considerations that need to be made when deciding on a loft conversion. This guide will go over the concepts and what you can expect to pay depending on the size and complexity of the building work involved. With this in mind:

A loft space cleared for a conversion
An example of a large roof space using roof lights

Professional Fees


These fees should not be overlooked when considering an extension and are all essential costs to be taken into account. For example:

  • Architect fees range between £1,000-£2,500
  • Householder planning application £172
  • A certificate of lawful development £86 is recommended when planning applications are agreed to prove building rights, particularly useful when selling the property.
  • Building control fees average £1100
  • Building regulation fees average £420
  • Engineers structural design fees average £1200

These fees do vary and there is likely to be additional costs depending on the works you’re considering.


Roof Types


We will cover the main types of roof you are sure to have below, it is possible to find guides for more detailed jargon-free information as well. There are some key areas you will need to consider such as:

Roof Structure 


The current roof structure in your property will dictate the type of loft conversion that is achievable. Here we will cover 3 of the most common types of conversions which are:


Roof lighting


The most cost-effective way to create a loft conversion. This involves simply putting in windows in the roof to allow in natural light. The limitation here is that the roof space will need to be high enough that you are able to stand up and move around without any changes to the roof structure.

Roof Lights in Upminster Essex
an example of roof lights



A very common way in which the space in the roof is extended in order to provide the headspace needed to allow for someone to stand in the loft. Dormers extend the roof at a 90-degree angle and can vary in size from a small section of the roof to a large dormer which can cover an entire face of the roof. Another example is:

A loft conversion in upminster
A dormer roof we recently installed

Mansard conversions


Typically Involve replacing one or both sides of a roof in the event that there isn’t enough headroom to use the space. For example, they are built with a steep wall edge with a flat roof on top in order to create enough headspace where there wouldn’t have been previously. These can typically be larger works and therefore come at a higher cost but nevertheless often provide more room than would have been possible.

Existing space available: What space do you currently have in the loft? Will this be large enough to form a room or will works need to be undertaken to expand the space?

Staircase: Will alterations need to be made to allow for the staircase to fit into the property?


Each of these will play a significant role in the cost of your loft conversion. Let’s take a look at some example scenarios to give some rough estimations.

Mansard Roof in Upminster
A good example of a mansard roof

Basic Room Loft Conversion Price


Estimated Cost: £14,0000 – £18,000

This would cover the cost of:

    • A staircase providing access to the loft.
    • Reinforced flooring.
    • Electrics, Lighting and Heating
    • Insulation
  • Fire Safety regulations to be met.


Dormer Roofing Conversion Cost


Estimated Cost: £20,000+

Adding a dormer to the roof will increase the headspace without requiring a complete restructuring of the roof.

This will allow a much greater flexibility when planning out where the stairs can go and how the room can be arranged.

What works are taking place can see the price significantly increase if for example a bathroom is being added as well as a bedroom.

Loft Stair Example
An example of loft stairs

Structural and Roofing Changes Conversion Cost


Estimated Cost: £40,000+

This is the more complex option that allows for the greatest flexibility. By altering the roof structure it is possible to add a lot more space to the loft conversion. This could mean putting multiple rooms into the loft space such as a study, bedroom and bathroom.




Adding additional space to a property will in almost all circumstances add value to your property. Many people are now opting for loft conversions over moving to save themselves money and time in the long run.

If you’re considering the cost of a loft conversion it is always best to speak with an expert and source quotes from reliable, well-established builders.

If you have any questions feel free to leave a comment or hit up our contact us page and we’ll be happy to help.

Based in Essex, including Upminster, Romford and Brentwood? Get in touch today to arrange a free quotation.