Dormer Loft Conversion versus Velux Loft Conversion, which is best? & how much do they cost in 2021?


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Loft Conversions

If you are in the research phase of your loft conversion project, this article will help you make an educated decision as to what type of loft/attic conversion may be best for you.

Whilst there are several different types of loft/attic conversions the 2 main types are:

  • Dormer Loft conversion
  • Velux Loft conversions

Which type of loft conversion is right for my home?

How much does a Dormer Loft conversion cost compared to the cost of a Velux Loft conversion?

In 2021 the minimum cost of a Velux Loft Conversion is around £50,000.00 + the VAT.

In 2021 the minimum cost of a Dormer Loft Conversion is around £70,000.00 + the VAT

These are the costs that we are typically seeing back from Building Contractors in 2021

The type of loft conversion you opt for will normally come down to budget, if your budget is tight then maybe you will opt for a Velux Loft/attic conversion. If you have a bit more money to spend then you can consider a Dormer Loft conversion.

Dormers can sometimes evoke images in your mind of ugly 1970’s style boxes stuck on the side of your roof, fear not, they can look awesome if designed correctly, with a plethora of materials to choose from for a real contemporary look.


Contemporary Dormer window

Dormer Loft Conversion verses Velux Loft Conversion


The case for Velux Loft/Attic Conversions

What is a Velux loft conversion?

A Velux Loft conversion is when the shape of the existing roof is retained and Velux windows are installed into the rafters, the rafters will have to be cut depending on the size of the new windows, the inside of the roof space is fitted out to a carefully thought out design

On a side note, there are alternatives to Velux when considering what type of Roof lights to install, one of these is Fakro, top quality, and value for money.

If you want to go for a frameless ultra-modern look then this crew is worth checking out… it’s worth considering the options.

The reason its referred to as a Velux loft conversion is that Velux is a brand name in as much as we say we are going to do the ‘hoovering’……….. there are other brands available!

A Velux loft conversion is generally the easiest and most economical to do because the structural alterations will be kept to a minimum. You will be working within the existing shell of the attic space.

There is still a strong chance some structural alterations will be required, sometimes more than you had imagined!

The structural alterations that are required will be dependant on the existing roof structure. For example:

Was the roof originally designed with a future conversion in mind?

Room in the roof trusses

Room in the roof trusses


Was the roof designed just to be ‘a roof’?

loft conversion in Edinburgh

W roof trusses

The existing roof structure will significantly affect the cost of your loft/attic conversion, extra strength graded timbers or steel will be needed to give the roof the strength it needs for the demands that will be placed on it.

Just think of all the extra weight with People, furniture, new walls, bathroom & holes cut in the existing roof structure for windows and a staircase.

As a rule, houses built before the late 1960s tend to have much more substantial timbers in the roof, better for a loft conversion…no question.

House built from the late 1960s tends to have factory-made roof trusses which tend to prove more challenging for a loft conversion although it can still sometimes be done.


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You can still achieve a great look Velux windows and there are no hard and fast rules as to how they should be set out, the key is not to skimp on windows which don’t cost much in the scheme of the project, put in as many as you can afford.

loft conversion Edinburgh

loft conversion Morningside


For a fantastic feature, a balcony window can be added to your Velux loft conversion.

Edinburgh Loft Conversion architects

Stunning Velux Cabrio Balcony Windows

Loft Conversion Costs

To help you understand what the costs might be, we have included two recent project examples:

  • A Semi-detached bungalow Velux loft conversion
  • A detached bungalow Dormer & Velux loft conversion.


How much does a Velux Loft Conversion cost in 2020?

Below we have included the costs for a Velux Loft conversion in a semi-detached bungalow: this bungalow had Factory made W roof trusses which is a lightweight roof and has been engineered to work as a roof and not withstand loads that come with a loft/attic conversion.

So, this was a little more challenging but far from impossible, three steel beams were inserted, 1 at a high level the other 2 at floor level with timbers fitted between the low-level steel.

In the end, the customers were delighted with the result which gave them a lovely master en-suite bedroom, a lot of space for the cost of the loft conversion, especially when you consider the cost of moving to a larger house, all the legal and professional fees attached to moving, not to mention the stress of moving. (these customers were able to live in their house in Spain while the work was being completed, I know, it’s a hard life!)

How much does a velux loft conversion cost in Edinburgh?

Velux loft conversion


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How much does a Velux Loft/Attic Conversion cost in 2020?

TOTAL £45,793.00



The case for Dormer Loft/Attic Conversions

What is a Dormer Loft conversion?

A dormer loft conversion is when the existing roof has been cut and extended outward to create extra space within the roof, this will add a feature to the space and make more of the floor space usable.

How much does a Dormer attic conversion cost in Edinburgh?

Dormer Attic Conversion

A dormer Loft/Attic conversion will generally require more structural modifications than a Velux Loft conversion, therefore will cost more.

The benefits of a dormer loft conversion are:

  • More useable floor space
  • Better head height
  • Create a feeling of ‘space’


Usable Floor Space

A Dormer loft conversion will create more usable floor space, this is because the rafters are cut and an ‘extension’ will be fitted into the roof space, this creates a more traditional feel to the room.

You can walk to the edge of the room without banging your head!

Dormers can come in all shapes and sizes and can be clad in all sorts of materials, they can be very contemporary or very traditional, it will come down to personal taste.

Often a contemporary style dormer can complement a traditional building very well.

Dormers can be constructed offsite and craned into position:

These can be insulated, clad and glazed in the factory or workshop and craned into position, usually fitted and secured in less than 1 day.

There are huge benefits to this type of construction technique which is increasing in popularity.

Having said that most of our Dormers are built on-site by the contractor, there is more room for error this way:)

How much does a Loft Conversion cost in Dundee

Off-site Dormer construction

Edinburgh Loft Conversion

Dormer seating


Dormer Construction

As a general rule of thumb the bigger the dormer the more structural alterations that will be required, the higher the cost.


How much does a Dormer Loft Conversion Cost in 2021?

We have outlined the costs for a Dormer loft/attic conversion below.

The existing attic space was generous and was crying out for conversion, a master en-suite bedroom, & a study was created. The dormer allowed space for a generous bathroom and a top stair landing.

Structural alterations were made to the roof which included both extra timbers and steel to allow the large dormer, 4 Velux windows, and staircase to be installed.

The staircase is located in the existing hall, albeit with the removal and relocation of some stud partition walls downstairs.

This Dormer Loft conversion is a magnificent addition to this bungalow, which has completely transformed this property, its now a proper family home, well balanced with the right amount of bathrooms and bedrooms.

How much does a Dormer Loft Conversion cost?

Dormer Loft Conversion Roof Plan


How much does a Loft conversion cost in Perth?

Dormer Loft Conversion


Cost of a Dormer Loft/Attic Conversion

TOTAL £72,056.00


So, Which is Best A Dormer Loft Conversion or a Velux Loft Conversion?

As we have seen both of these loft conversion types have merits.

so, now that you know the difference, you will be better placed to make a judgment as to what will be most suited for your project, taking into consideration your budget and the extra space that you require.

if you are worried about investment potential, you might well be asking:

Will a Loft /Attic conversion add value to my house?

It might, this will depend on a few things:

  • Property Location
  • Quality/Design of the Work
  • Ceiling price on your street

If you live in an area, say Edinburgh, where property prices are high then a loft conversion will not only be a great addition to your home it will also be a great investment.

There are lots of instances where the return on investment will be 3 or 4 times the cost…..so good news.

A critical element to adding value is the design, you only get to do this once so it’s got to be a great design, make sure you get a specialist to design your project, a bad design can devalue your property…not good.

Don’t skimp on windows or be tempted to cut corners, make sure there is plenty of light getting into the loft space, light and bright is good for a loft conversion.

If the amount you will spend takes you over the ceiling price of the houses in your street then it probably won’t work as an investment. If that’s the main driver then it may be worth reconsidering your options.

It’s fair to say though that while it’s nice to know that the money we will be spending is a wise investment for the majority of our customers this has been secondary to how this will improve their home and ultimately their quality of life.



If you are ready to move ahead with your project or just require advice, contact me for a chat john@jwarch.co.uk

OR Book a call here

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