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Last updated: 8 May 2024

Loft Conversion Terraced House UK: A Complete Guide (2024)

Many terraced houses are suitable for loft conversions. In fact, adding a terrace loft conversion to your house can raise its value by 20% and transform it into a more comfortable living space.

  • Terraced house loft conversions on avergae cost between £1,150 - £2,500 per square metre 
  • The most common conversions types are Velux, rear dormer, L-shaped dormer and mansard 
  • Planning permission is not necessary as long as the conversion is not located in a conservation area or an area of natural beauty 
  • According to planning regulations the conversion can only increase the property’s volume by 40 cubic metres 
  • A Party Wall Agreement must be served on both sides of the property to comply with the rules and regulations

Loft conversions can be a great way to add value and space to your terraced home. Whether you are looking to convert your loft into a functional area or create extra living space, this guide will highlight the main factors that are necessary to consider before the conversion.

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Can You Convert Your Loft an a Terrace House?

Absolutely! It is often possible to convert the loft in a UK terrace house, and in fact, loft conversions are quite popular in such properties. However, the price will depend on the size, internal structure and location of the house. A loft conversion may not be possible in unpermitted regions as conversation areas or areas of natural beauty (AONB).

While there may be some differences in the roof structures between end-terrace and mid-terrace houses, loft conversions are generally possible for both types.

Terraced homes constructed before the 1960s, typically have larger lofts with enough headroom for a loft conversion since they also frequently have steeper roof pitches.

To get the best quotation for your conversion, it's highly recommended contacting multiple installers. This way, you can compare personalised quotes that suit your needs. 

GreenMatch can help you prevent wasting your valuable time and money by letting you compare quotations directly from certified installers in our network for free. Within 48 hours after completing our short and simple form, you will receive loft conversion quotes from up to four installers.

What are the Options for a Terrace House Loft Conversion?

Terraced houses can allow for either Velux, dormer or mansard loft conversions. Generally, a dormer is more popular and it adds usable headroom and expands the floor area while enabling the installation of vertical windows. Let's explore all the types together:

Velux conversion
If you are looking for a simpler and more affordable loft conversion, it is possible to add Velux windows, sometimes referred to as a rooflight or skylight loft conversion. 

With the exception of some rooflights that have been added and integrated into the current roof, the roof's structure is unaltered. This can transform a poorly ventilated area into one that is light and spacious enough to be used as a living space.

This type of conversion is perfect for those who look for a quicker and less complex project. However, if you wish to substantially increase the size of your attic this option might not be the optimal for your loft.

Rear Dormer
Rear dormers are a popular option for loft conversions as they are relatively straightforward to build and can add a substantial amount of additional space, turning an unusable loft into a living area. They typically extend from the back of the house.

L-shaped Dormer
This type of dormer extends to the side and back of the house in an L-shaped structure. It allows for a variety of room layouts due to their shape. This type, provides substantially more space compared to a rear dormer conversion.

Hip-to-gable conversion
This conversion involves extending the hipped (sloping) side of a roof to create a vertical gable end. This type of conversion is commonly done on terraced houses to maximise the available space within the loft, thereby increasing the space in the room.

This loft conversion has a level roof and a rear wall that slopes inward. This form of conversion often entails replacing one or both sides of a sloping roof with a nearly vertical 72-degree pitch, resulting in extra space and full headroom.

What You Need to Consider Before Starting a Terraced House Loft Conversion?

Before commencing a terraced house loft conversion it is important to consider key factors that are essential for the project. These include the type of roof, the stairs and space assessment, planning permissions as well as building regulations.

The Type of Your Roof

The type of roof you have determines the project's complexity and costs. It can be challenging to construct a useful space in the loft because the highest point of a traditional truss is usually about 2.5 metres high. In contrast, modern trusses can reach a height of three metres, giving a loft conversion greater room.

Nearly all recently constructed homes have the modern truss roof form. The inside of the first floor of these homes is typically not constructed with load-bearing walls. It could be necessary to use the surrounding walls as support for the new timber suspended floor.

Older homes typically have traditional cut and pitched roof forms that originated prior to the 1960s, which make loft conversions simpler. While they don't need as much height as a modern trussed roof, loft conversions still require structural calculations for modern trusses. In contrast to modern truss roofs, first-floor load-bearing walls are typically present and serve as support for the newly installed floor joists.

Stairs and Space Assessment 

One of the most crucial aspects of your loft conversion is determining the proper placement and design of the stairs. The placement of the stairs will determine where the furniture is placed in the new loft room.

Although it's not always feasible, the ideal location for steps in a loft conversion is directly over the current staircase from the floor below. If this doesn't work, it might be possible to build a new loft staircase in the fixed ladder or alternating tread styles, at a straight angle to the current staircase (especially in smaller buildings). 

The loft stairs can incorporate turns or landings to ensure safety and practical entry. You can enter or exit the loft without the risk of injuring your head.

If your loft conversion includes a third storey you must guarantee that a protected stair enclosure proceeds down to the outer escape door. If your staircase rises from a room other than the hallway, you have several possibilities.

According to fire regulations, your loft conversion's new floor joists must provide at least 30 minutes of fire protection, which could require replastering the ceilings of the rooms below.

Planning Permission

In many cases, loft conversions fall under permitted development rights. Check with your local planning department to determine if you need planning permission for the conversion. 

There is no need for you to apply for planning permission as long as the loft conversion satisfies certain requirements. The house cannot be in a conservation area or AONB (area of natural beauty). Additionally, the conversion can only increase the property's volume by 40 cubic metres. 

If the loft conversion complies with these requirements, your permitted development rights will allow it to be finished without official planning permission from the local government.

Building Regulations

Following building regulations is essential when undertaking a loft conversion. These standards are designed to ensure the safety, structural integrity, energy efficiency, and accessibility of buildings. 

It is important to consult with building control officers or inspectors early in the planning process to get advice specific to your project and ensure compliance with all relevant regulations.

Structural Stability: The existing structure must be able to support the additional load introduced by the loft conversion. This may involve strengthening the floor and roof structure.

Fire Safety: There are usually requirements to ensure that the loft conversion meets fire safety standards. This may include the installation of fire-resistant doors, fire barriers, and escape routes.

Escape Routes: Adequate means of escape in case of fire must be provided. This may involve the installation of fire-resistant staircases or escape windows. The stairs need to have a width of at least 600mm with no more that 16 stairs. Additionally, it is important to have 2 metres of clear headroom over the stairs. 

Insulation: Loft conversions are typically required to meet specific insulation standards to ensure energy efficiency and thermal comfort. The required minimum insulation thickness is 270mm. 

Ventilation: Proper ventilation must be provided to prevent issues such as condensation and mould growth. This may involve the installation of windows or ventilation systems.

The Type of Your Property

It is important to consider whether you have an end-terrace or a mid-terrace property. You have to obtain two party wall agreements - according to the Party Wall Act - as mid-terrace houses have party walls on both sides. This can limit the options for certain types of loft conversions, especially if you’re considering extensions that impact the party walls. 

On the other hand, the roof structure of an end-terrace house is different from a mid-terrace as only one wall is shared with a neighbour. Therefore, there are more options available for conversions as only one party wall agreement needs to be arranged.

End-terrace houses may have more flexibility for dormer windows on the side or rear of the property, providing additional headroom and floor space. In some cases, an end-terrace loft conversion might be part of a larger project that includes a wrap-around extension, especially if there is available space on the side.

How Much Does it Cost to Convert a Loft in a Terraced House?

Loft conversion terraced house costs can vary between £20,000 to £75 000 and take 6 to 14 weeks to complete depending on the type of conversion. 

For a small Velux conversion of 20m2 the cost ranges from £23,000 - £27,000. The cost of a  30m2 medium rear dormer conversion ranges between £30,000 - £50,000.

Typically, a Velux loft conversion is the cheapest conversion and a mansard loft conversion is the most expensive. The location, state of your current loft, and the type of conversion affect the total cost.

When determining your loft conversion price it is important to note that additional costs may include architect fees, building regulations fees, planning application fees, and possible Party Wall Agreement payments.

Conversion TypeAverage Cost Per m2Average CostCompletion Time 
Skylight (Velux) £1,150 - £1,350 £15,000 - £25,0006 - 8 weeks 
Rear dormer £1,250 - £1,350£25,000 – £50,0008 - 11 weeks 
L-shaped dormer£1,250 - £1,450£30,000 - £60,0008 - 12 weeks 
Hip-to-gable£1,500 - £2,500£40,000 - £70,00010 - 12 weeks 
Mansard dormer£1,500 - £2,500£40 000 - £75 00010 - 14 weeks 

Notably, if a property already has stairs leading to the loft, it might result in a lower cost since adding stairs is a significant part of the expense in some loft conversions.

What are the Benefits of a Terrace Loft Conversion?

A terrace loft conversion in the UK can offer many various benefits. Here are some advantages associated with terrace loft conversions:

Increase in Property Value

A loft conversion can raise your property’s value by up to 20%. For example, adding 24 square metres of newly built space can increase the value of your terraced property by £90,000 or more. The increase in value will depend on the type of conversion you carry out, if you choose to add a bathroom, and the finishes you select.

Houses in the North East will gain up to £38,000 in value, whilst in the South East, the same amount of space would gain £98,000 approximately. However, depending on transportation access routes to London, this number may decrease in the South East. The more attached you are to the capital, the higher your property returns.

Improved Energy Efficiency

Although most homes currently have insulation, the regulations determining its thickness have evolved over time. It is currently recommended to have an insulation thickness of 270mm.

You can reduce heat loss via the roof by upgrading or making an investment in better insulation during the conversion. Reducing heat loss during the winter months results in lower heating costs and increased energy efficiency. Improving insulation can prevent heat loss in the winter and maintain a cooler interior during the summer.

Sustainable Use of Space

Converting a loft allows for the utilisation of the existing space without the need to extend the house. This is a more environmentally friendly approach because the existing structure is maximised rather than utilising natural land. 

Additionally, the longevity of a property is improved as you can expand vertically, instead of having to move in the case of your family expanding or if there is a need for more space in the household. This in turn, can reduce the demand for new construction and its associated environmental impacts. 

Natural Light and Ventilation

A loft conversion that includes features like skylights and windows reduces the reliance on artificial lighting and mechanical ventilation systems which in turn, lowers energy consumption. The features can also make the loft more comfortable during use.

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