How much does a dormer loft conversion cost?

What are the benefits of a dormer loft conversion?

Dormer loft conversions are particularly popular for several reasons:-

• They create not only additional floor space but also extra headroom so they are ideal for loft conversions which would otherwise not have sufficient roof height
• They can open up existing loft conversions which are small and gloomy creating both more floor area and natural light
• The additional headroom provides more options when it comes to the location of the staircase
• Dormer loft conversions can improve the external aesthetics of a property rather than completely alter it in the way a Mansard loft conversion does
• A dormer loft conversion can increase the value of your home by around 20%-25% depending on what the internal accommodation is used for – bathrooms and kitchens will always add more value than extra bedrooms. This means the cost of a dormer loft conversion could be offset by the additional value added to the property

What is the procedure for a dormer loft conversion?

The builder and the architect will consult the homeowner about their intentions and undertake a site inspection so that the architect can draw up the plans. Then it will be necessary to apply for planning permission. Your architect or surveyor must also liaise with your neighbours if you are in a terraced row or semi-detached property as you will require a Party Wall Award under the 1996 Party Wall Act and this must be in place before the work can commence. The final regulatory process before construction can start is the Building Control approval. The plans have to be submitted to the Local Authority and the Building Inspector will set up a series of site visits to check that the construction complies with current building regulations. This has nothing to do with planning permission. Only after all this is in place can work begin. This is a typical timetable for a dormer loft conversion:-

• The loft needs to be cleared of any possessions and the water tank removed and replaced either with a sealed system or an unvented system which dispenses with the requirement for a header tank
• Plumbing and electrical wiring are re-routed and new services installed
• Floor joists are either reinforced or re-fitted
• The floor is insulated and floorboards laid
• Scaffolding is erected around the roof of the house to gain access to the external roof planes
• The roof is opened up to accommodate the new dormer windows which are fitted, glazed and tiled
• The new staircase is installed
• The roof is insulated
• Partition walls are fitted if there is to be more than one room in the new space
• Plastering and carpentry work is completed
• Final decoration is finished or installation of fittings for a new bathroom or kitchen are completed depending on the choice of accommodation

What can a dormer loft conversion be used for?

A dormer loft conversion can create much-needed family accommodation and avoid the requirement for a costly and undesired house move. It is also an option if the potential to extend at ground floor level has been exhausted.

Here are some popular uses for the extra room that a dormer loft conversion will create:-

• A home working space or studio
• One or two extra bedrooms
• A luxury master bedroom with en-suite bathroom
• A rooftop cinema and media room for all the family freeing up the sitting room or lounge to be used for something else like a playroom for small children or a home office or study
• A spacious bedroom and study area for a teenager or student
• A large dormer loft conversion can be used to create a kitchen and living/dining area. Match this up via the staircase with an en-suite bedroom on the floor below and you essentially have a self-contained annexe for an adult child, a lodger or an elderly relative

Not only does a dormer loft conversion add extra rooms but, depending on what you use it for, it can also free up other space in the home which is then available to be put to use for a different purpose.

Are there different types of dormer loft conversion? Are costs different?

There are essentially two different types of dormer loft conversion:-

• Gable fronted dormer or gabled dormer – this is the most common type of dormer and consists of a pitched roof of two sloping planes supported by a frame which rises vertically to form a triangle shape below the roofline. These dormers resemble dog kennels and are sometimes referred to as dog house dormers.
• Hip roof dormer – this is a roof which slopes upwards on the three sides so there are no vertical sections. The point at which the three sloping planes meet is called a hip. The term, hip bevel, refers to the degree of the slope

Why type of dormer conversion should I opt for?

Some of your decision will be based on the cost of your dormer loft conversion and practicality but what the finished conversion will look like from the outside is also important to many homeowners. Dog house dormers really suit traditional and old-style properties especially country cottages where they can sympathetically create more space without spoiling the appearance and aesthetics of an old building.

The choice of dormer and how many dormer windows to have will usually be governed by budget, the design and size of the conversion and personal taste.

How are the costs apportioned on a dormer loft conversion?

Your roofing contractors estimate will be split the cost of your dormer loft conversion between labour and materials and there will other charges such as the hire costs for the scaffolding platform and waste disposal charges.

What other dormer costs will there be?

• You will need to employ an architect to produce the drawings and typically their fees for this type of work are between £800-£1,000 plus VAT
• Planning permission will be required because of the structural changes to the roof and there is a set fee for this which is currently around £170
• If the property is in a terraced row or semi-detached, your neighbours will need to be notified of the works and give their permission; this is a legal requirement under the provisions of the 1996 Party Wall Act. You might need to appoint a Party Wall surveyor (although commonly the architect who draws up the plans will perform this function). If your neighbour appoints one as they are entitled to do then you will be liable for both sets of professional fees
• A dormer loft conversion will also require approval from the Building Inspectors who work for the local authority. They will need sight of the plans and will arrange to visit at set times during the construction process to ensure that the build is compliant with modern building regulations. They are responsible for signing off the works before the final interior fitting out and decoration is completed and issuing a completion certificate after the last inspection. This also attracts a fee which is typically in the region of £400-£800.

What else can impact on the cost of a dormer loft conversion?

It can be easy to overlook the impact that a dormer loft conversion might have on the rest of your home other than focusing on the extra accommodation it will create. There can be implications to your property which will also carry a price tag and ultimately affect the final cost.

This new part of your home will require light and heating and it may also require plumbing if you fit either a kitchen or a bathroom to the new space. All of these potentially put more pressure on your main services which could require re-routing or even upgrading:-

• Some householders will fit a new boiler if the heating requirement is too onerous for their existing system. A couple of well-insulated bedrooms might not add too much demand but a new bathroom will
• A loft-based water tank will need to be removed and relocated, a header tank can be replaced with an unvented system or the existing hot water system can be swapped to a sealed system
• Fitting a staircase on the floor below may involve remodelling work and redecoration depending on its location

It may be necessary to upgrade the roof and many homeowners use a dormer loft conversion as an opportunity to refurbish their roof and undertake any other necessary upgrading or repair works whilst the scaffolding is in situ.

A traditional framed roof probably requires less work for a dormer loft conversion although the rafters may need reinforcement. A trussed roof which is usually present on more modern houses will require greater structural upgrading.