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Extension or Loft Conversion: Which Is Best?

Loft convesion with white wooden walls, a white sofe, large windows ans kitchen features in the background

A Loft Extension or conversion can be a great way to add extra space and value to your home. However, it can be hard to separate the differences between them. Keep reading to find out which one is right for you, and how you can build your ideal space, whilst saving money and maximising property value.

If you’re considering a loft conversion, view our range of loft skylights.

What’s an extension?

An extension is a form of home improvement that lets you extend the existing space in your home. This could be adding an extra room in the form of: a bedroom, a toilet, a bathroom or utility room. It could even simply be extending an existing room. Types of extension include: single-storey, double-storey and conservatory.

View our range of bedroom and bathroom skylights.

What’s a loft conversion?

Unlike an extension, a loft conversion usually works with the existing space, renovating it without extending the property. There are a number of different types, which include: Mansard conversions, Dormers, Internal Loft Conversions and Rooflight conversions. You can find out more about the different shapes and types of loft conversions in our guide.

What’s cheaper, an extension or loft conversion?

Generally, loft conversions are the most cost-effective. On average, a loft conversion costs from £27,500-£75,000, whereas an extension costs between £25,000-£112,500. However, the overall cost will depend on the price of the materials you choose, as well as the size, shape and complexity of your design. The budget is even affected by your chosen finish and windows, as well as loft ventilation options. Additionally, you’ll need to consider any required planning permission costs or building regulation fees. 

Any required labour costs, including surveys and structural engineer fees, will need to be considered, with any required insurance that comes with the project. Design costs are also a vital factor – as you’ll need an architect to put together plans. This is especially important if your design is more bespoke or complex. 

What adds more value?

Generally, a loft conversion has the potential to add greater value. This is because the addition of new bathrooms and bedrooms tends to add the most value to a property when it’s sold. Both loft conversions and extensions could add up to between 15 and 20% to your property value. This could even rise to as much as 24.5%. However, this also depends on the materials, type of living space added and the finish used. For example, garage conversions can add 10-20% to your home, especially if you convert them into a home gym, office or playroom. Also, a double storey extension adds slightly more than a single-storey extension. With any additional bedroom, you should make sure that there’s sufficient living space to account for an extra tenant to preserve the added value.

The value any home improvement adds to your property also depends on its location; we’d always recommend speaking to your local estate agent before completing any renovations. Their knowledge of the local market will help you to determine the home improvements that will best benefit your property. 

Learn more about how to add value to your home.

Which will suit my house better?

This depends on the space you’re working with and your goals for the space. If you’re wanting a new bedroom, for example, a loft conversion is the most suitable option. However, a general extension might be better if you’re looking to add more general living space to your home.

If you’re looking to add:

  • Another bedroom or bathroom 
  • The chance to experience surrounding views from the highest spot in your home
  • Additional storage space 
  • A home office 
  • Value to your home
  • Potential increased energy efficiency 

Then a loft conversion may be for you. On the other hand, an extension lets you add any room you want, or increase the available living space. You should also consider what will work best for the aesthetic of your existing house – this is especially important as, in order to get building regulations approval, the materials used must be similar to those used on the original house.

Which will add more space?

An extension will add more space, as it extends the dimensions of your current property, whereas a loft conversion helps you maximise on the space you already have. You could get a single or double-storey extension, or get a conservatory to increase your available living space. However, it’s important to think about the space an extension may take away from parking spaces or your garden, which can impact your day-to-day life, as well as your property value. A conversion is a great way to help you take advantage of the space you have, effectively using any dead space you have in the roof.

Do either require planning permission?

Conveniently, a loft conversion is generally classed as a permitted development. However, as with an extension, this is only if it meets the regulations:

  • The total area of the additional space won’t exceed 50 cubic metres (detached or semi-detached houses), or 40 cubic metres if the house is terraced 
  • The roof enlargement doesn’t overhang the outer face of the house’s original wall
  • Any side-facing windows are obscure-glazed to stop anyone from seeing into the house (frosted or patterned) 
  • Also, openings for side-facing windows should be 1.7m or more above the floor 
  • Materials used should be similar in appearance to the existing house  
  • The extension doesn’t go higher than the highest part of the roof 
  • There are no raised platforms, verandas or balconies 
  • Roof extensions (aside from hip-to-gable ones) are set back as far as possible – they should be at least 20 cm from the original eaves 
  • Your house should not be built on designated land, such as national parks, the Broads, conservation areas or national parks, or a World Heritage site 

You must also have not used the property’s permitted development rights to build an additional storey. If you’re unsure, you should always speak to your local authority, and seek the advice of the architect or builder working on the project. 

If your work is being carried out near or on a shared property boundary, you must also have a Party Wall Agreement. Party walls are classed as those that stand on the land of 2 or more owners and form part of a building, or don’t form part of a building, like garden walls (excluding wooden fences).

Which is the least disruptive?

If you’re having a large extension built, this will be more disruptive, as you may have to vacate a large portion of your home, or leave your home completely for a while. Whereas, in the case of a loft conversion, the disruption is generally more manageable due to it being isolated to your existing space. Although depending on the complexity of the design, an extension is more likely to take longer than a loft conversion to build, with a conversion taking around 6-10 weeks, and an extension taking anywhere from 3-10 months.

Rooflight options

Rooflights for extensions

Rooflights are a great way to bring in additional natural light to your extended space, as well as high quality glazing helping to increase the energy efficiency of your space. It can even help open up a room, or provide another way to enjoy the sky on a clear day from the comfort of your home. You could go for the elegant chicness of a Fakro Top Hung Roof Window, or the unique and eye-catching look of a Circular Rooflight. Alternatively, you could opt for a more traditional Wendland Roof Lantern

Loft conversion rooflights

Rooflights are one of the most cost-effective ways to elevate and transform your existing loft space. They allow you to increase the amount of natural light entering the space, without changing the structure of the existing roof. The type of rooflight you choose can greatly affect the feel of your space, and make it feel more open and airy. It can also help you take advantage of the view from the highest point in your house. That’s why it’s important to pick the one that best suits your vision. You could opt for the practical and tasteful simplicity of a Coxdome Electric Glass Opening Rooflight, or go for a more modern feel with a Flat Rooflight. Shop our range of rooflights to find the perfect one to reinvent your space! 

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What are the disadvantages of loft conversion?

A loft conversion can leave you with limited space to work with, and not all houses are suitable for this type of home improvement. For example, your house may have restrictions surrounding roof structure, a low loft ridge height (meaning you may need a roof lift loft conversion). Head-height limitations may make it difficult to place furniture or stairs in a way that preserves functionality, whilst still following building regulations. You may also need to consider any additional structural elements needed to support the added weight of the new space.

The loft conversion also comes with challenges surrounding insulation, due to the variations in loft shape often needing more bespoke insulation solutions. Also, loft conversions can pose accessibility challenges due to stairs, so an extension may be more beneficial for those who need additional space on more easily accessible lower floors. 

Should I do a loft conversion or move house?

This depends on your reasons for wanting the conversion. If you need a larger house with more rooms or are looking for a change of scenery, then moving house may be your best option. However, if you’re looking to make the most of the space you already have, and increase your property value in the event that you do move, a conversion is a great way to do this. Ultimately, your local estate agent will be able to advise you on the best possible decision for you, based on current market insights and your requirements.

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