Your loft conversion price will depend on a range of factors, including the existing roof structure, the type of loft conversion, the complexity of your design, where you’re located, and professional and planning fees.

Be sure to consider the following when planning your budget:

Planning permission for loft conversions

In most cases planning permission isn’t required for a loft conversion as it falls under the category of Permitted Development - one of the most appealing reasons for doing a conversion! However, make sure you don’t assume. If you live in a period property or conservation area, or if your conversion plan involves extending or altering the roof space in a manner that exceeds specified limits and conditions, you may need full planning permission. In 2019 the fee is £209.

Get in touch with your local council and check if you need to apply. The UK Government website also has further guidance on permitted development.

Types of loft conversion

There are several different types of loft conversions available. The more complex the conversion and more structural alterations required, the higher the cost will be. 

• A room in roof conversion (often called a Velux conversion) is the most simple type as it doesn’t require alterations to the outer structure of the home. It’s ideal if you already have sufficient roof space (a minimum of 2.1 metres). Roof windows are added to provide light for the converted space. 
• A dormer conversion extends out from the back or side of the roof into a box shape, which creates more space in the loft room. Prices will vary depending on how many dormers you add. 
• A hip-to-gable conversion can be ideal for semi-detached or bungalow properties that a hipped roof with sloping side. The hip side of the roof is converted into a flat edge which creates space inside the loft.
• a Mansard conversion is the most pricey option and involves altering the angle of the roof slope to make it almost vertical. The conversion has a flat roof, with the back wall sloping inward at a 72 degree angle. Planning permission is mostly likely required due to the major changes to roof shape and structure.      

No matter what type of conversion you choose, you will need to budget for:

• A staircase to access the loft room
• Electrics and lighting
• Plumbing (if you are including a bathroom)
• Heating
• Fire safety
• Loft insulation and ventilation
• Floor reinforcements

Professional fees for loft conversions

To get the loft conversion of your dreams you’ll need to work with a range of professionals. The price will vary according to the approach you take. Loft conversion specialists can sometimes be a good value option as they handle the whole process from design to build. Alternatively you can have an architect draw up plans then appoint a contractor to carry out and manage the build. Or if you feel confident you can make savings by project managing the build yourself and appoint contractors of your choice.

Legal fees for loft conversions

Be sure to factor in legal charges such as building regulation fees. The finished conversion must be inspected by the local council to ensure it complies with fire safety and building regulations. You’ll then be issued a completion certificate.

Contingency budget

No matter how carefully you plan your loft conversion project, the unexpected can always be expected! It’s good to budget a 10% contingency.

Want more advice for starting your loft conversion? Check out how to put together your building project team and 12 tips for choosing an architect.