How Much Do Loft Conversions Cost?




how much does a loft conversion cost?

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Although prices vary throughout the country loft conversion costs range from £26,000 for a basic Velux conversion to £80,000 for a full dormer. The final cost will depend on the size of the floor area, location, and whether skylight or dormer windows are required.

There are also other factors to take into consideration. The state of the economy can impact on the price of materials, the availability of builders, and, most significantly, the type of loft conversion.

For example, a full conversion with a dormer will cost far more than a shell loft with skylight windows. In a similar manner, a mansard conversion will be much more costly when compared to converting the loft of a terraced house.

What are the costs in a loft conversion?

Some of the costs you’ll pay out are obvious. Your builder will take the biggest slice but there are other expenses which you may not have considered. Party wall surveyors for example.

Let’s look at your shopping list though some of this expenditure may be bundled together by your builder.

Specialist builder.
Plumbing and heating contractors.
Party wall surveyors (you may end up paying for two or even three of these).
Planning application fees.
Building approval fees.

Added to this list the cost of your loft conversion will depend on the type of roof on your property, the size and area of your loft, the number and type of windows, and where you live.

We’ll look at all these factors and what they mean to your budget in a moment. But to give you a rough idea using ballpark figures, a simple rooflight conversion for a 20 square metre loft with two windows will cost between £20-26,000. But this could rise to 40K for an inner London property or one where the outer structure of the house needs altering.

A simple truth is that the simpler a project is, the less it will cost. No surprise there. For example, if a 20 square metre loft costs £26,000 with skylight windows, substituting a dormer will probably add another £12-15,000 to the total cost.

By the way, those estimated costs don’t include final fittings such as showers, partition walls, fixtures and fittings, and decoration.

And those figures are presupposing no issues with planning, the build itself, or with the neighbours.

What affects the cost of a loft conversion?

Let’s look at some of the things we’ve listed above and why they affect the cost of your loft conversion.


As much as the politicians like to tell us there is no geographical divide in the UK, there most definitely is when it comes to the cost of loft conversions.

All things being equal the cost of converting the loft of a house in Northern Ireland or the north of England will be significantly lower than a comparable property in the south east of England.

If you’re in London you will pay far more for labour and materials and even the cost to the builders for parking their vans will add to the amount you pay.

Party wall surveyors

This is one expense which always catches people out. If you don’t share a party wall with a neighbour – happy days. But most of us will. And if that is the case you need a party wall agreement.

And to get one of those you really need the services of a surveyor. Especially if you have a neighbour who may object to you building your loft conversion.

You will need to pay your party wall surveyor and , if your neighbour objects to your building notice, and appoints their own surveyor you’ll have to pay for that too. It gets worse. If those two surveyors can’t agree on the party wall award you may have to pay for a third surveyor to function as a referee.

Considering these surveyors charge a very hefty hourly rate you will certainly be looking at over £1,000 for their services. Which is why you really need to keep on the good side of your neighbours, keep them fully informed of your plans, and serve your building notice as far in advance as possible.

Planning permission costs

Under permitted development rules, most loft conversions will not require planning permission. However, if your project does, you will need to pay a fee of around £1,000 to make a planning application.

You can find out more about this in our article: Do Loft Conversions Need Planning Permission?

Building control costs

You can’t avoid these. Even though your loft conversions may not need planning permission, you have to get building control approval. The fees associated with this will vary depending on where you are in the country and the size of your loft.

But you are probably looking at building control costs of around £600 to £800 for a loft conversion.

Loft conversion costs and added property value

The bottom line when planning any building project is ‘How much will it cost’. Which is only natural. We don’t all have unlimited bank accounts.

As we’ve mentioned the cost of converting a loft varies from region to region within the UK and, of course, no two conversions are likely to be the same.

But we can use some estimates and rule-of-thumb.

Of course there are various reasons for converting the loft, usually to add more living space of course.

But, there are other reasons and, arguably the most important, is that by building a loft conversion you should immediately add at least the amount you spend onto the value of your house.

And it just keeps on getting better.

Figures from surveys consistently show that a conversion which incorporates a bedroom and en-suite bathroom can add up to 20% to the value of your home.

Estimated loft conversion costs

Let me qualify what follows by saying we are not builders and all the costs we share here are estimated ballpark figures. Take them as a guide not gospel. Prices fluctuate and circumstances differ so do be aware of this.

In London loft conversions can cost up to £80,000 though around the UK the average is around the £30,000 – £45,000 mark.

These costs are when employing a specialist building company and they can be drastically reduced by doing some of the work yourself if you are handy at DIY. Though a do it yourself loft conversion isn’t for the faint hearted.

Much of course depends on the type of conversion you’re building. For example, a very basic storage solution can often be done in a few days and there are some specialist loft conversion companies who will, for around £2000, install loft boarding, a new hatch, lighting and a loft ladder.

But, for a full scale, and well-built loft conversion, loft conversion prices are usually somewhere between £26 – £80,000.

The following is a guide to the loft conversion prices you could expect to pay (note – figures are estimates which don’t take into account regional variations but still provide a useful guide)

Types of loft conversion and their costs

A roof light or Velux conversion with two windows, structural and electrical with stairs will cost between £26-30,000.

A dormer with all structural, electrical work and staircase will cost £45-£50,000.

For a hip-to-gable conversion you’ll need a budget of around £56-58,000.

The most expensive loft conversions will be for bungalows and those properties with a mansard roof.

A mansard loft conversion will cost between £60 and £65,000 while adding a dormer to a bungalow could cost up to £70,000.

A shell loft conversion, perfect for the DIYer, will cost in the region of £28-30,000 and include the structural work including dormer, new joists and floor.

Storage loft conversion to include flooring, lighting and loft ladder £1000 – £2000.

Of course there are so many different factors which affect the cost of a project but the above are useful ballpark figures. But, if you’re in the south east and particularly London you’ll be looking at adding around 20% to those estimates and possibly more.

Other estimated loft conversion prices

Builders will also be able to quote for different parts of the job and you may be able to save money by employing different contractors rather one builder. The flip side of that is you lose the convenience of one builder doing everything.

Nevertheless, let’s try and break down some of the component costs of a loft conversion (again with the estimate and location disclaimers applied).

Architect’s fees can range from around £500 to four times that depending on whether you want full plans drawn up.

Loft stairs (manufactured and fitted) £1,000 to £2,000 though if you want a funky design like a spiral you’ll be looking at many times that.

Plumbing and electrical work will probably come out at around £3,000.

Structural work including steelwork can cost up to around £8,000.

Roof lights (supplied and fitted) £700-£1000.

Dormer (built and glazed) £6,000.

Loft plans drawn up by an architect or other professional to be submitted as part of a building regulations application £500-£2000 depending on the complexity of the project.

The above loft conversion costs are a guide and adding extras will obviously increase the bottom line.

Another thing to consider is that there are builders who will do loft conversions very much cheaper than the prices quoted above.

Some people look to trim costs by not using exterior scaffolding, installing only one small roof light, compromising on materials, and circumventing the building regulations.

The advice on this site is to always do things by the book and to employ a specialist builder – but quality does cost more.

Will I get my money back?

It is by no means cast in stone but, provided the project is well planned, well built and, most importantly, well designed then the cost of the loft conversion should be recouped in added value to the property.

Estate agents and mortgage brokers repeatedly say that building an attic extension is by far the best home improvement project for adding value to a property.

It is important to remember that a property’s value is usually defined by the number of bedrooms in the house.

By adding an extra bedroom (preferably en-suite) in the attic the homeowner is almost guaranteed to add value to the property. It is little wonder that bedrooms are the most popular design for new attic rooms.

It is very important that the new attic room is designed to fit seamlessly into the existing design of the property. If the attic extension looks like a hurried or contrived bolt in addition then it is highly unlikely to add any value to the house.

Because of this it is important to get the staircase right and the new attic room should, from the inside of the property, look as though it was there when the house was first built.

Blanding in the new room to the existing property design will ensure that future potential purchasers will recognize the attic room as a valuable additional living space and will be more than willing to meet the cost.

What a loft conversion quote should include

When obtaining a builders quote you need to know exactly what your loft conversion cost includes.

Receiving a quote and digesting what it contains can be difficult as there will be plenty of technical detail in there, but it is important that you dig through the bumf and determine exactly what the quote does include.

So, what should you be looking for?

Naturally the first thing is that the quote should be in proper written form.

Don’t ever accept a verbal quote or one scribbled on the back of a fag packet for that matter.

Your quote and loft conversions prices should contain:

1) The builder is responsible for carrying out the requirements of the Party Wall Act and should give advance notice of the work to your neighbours.

2) Probably the most important part of the quote, aside from the bottom line figure, is that the contractor is responsible for complying with the loft conversion building regulations.

This should include making the application, ensuring the application’s success and Specifying if the cost includes paying all fees.

Hugely important is that the quote or final contract specifies that the work is only finished when the completion certificate is issued by the council’s building control officers.

3) The design and preparation of the plans should be included unless of course you are employing an independent architect or designer.

4) The agreed start and finish date of the project should be specified. This is important as you should insist on penalty clauses being included should work drag on beyond the specified completion date.

5) A payment schedule. Always make sure that when and what you will pay is in black and white. Never, ever, pay in full up front and you should only pay for each batch of work when it is completed though an initial payment for materials is acceptable and normal.

Making sure that all the above is included in the quote should ensure that your expenditure is kept under control and manageable.

Keep a bit in reserve

One of the best pieces of advice I have ever received was to add a 20% contingency fund to your budget.

No matter how accurate your initial budget forecast and no matter how good your project management skills there will inevitably be unforeseen costs that crop up.

By adding a 20% failsafe to your budget those unexpected additions to your loft conversion costs won’t throw a spanner in the works and will ensure that the project proceeds nice and smoothly.


There is nothing worse when looking at a loft conversion price estimate from a builder for him to say, “Of course there is VAT on top of that.”

Suddenly a figure that seemed reasonable and within reach has taken on a whole new dimension.

VAT is the scourge of us all and the levels payable for certain products are ambiguous and very confusing.

And calculating the level of VAT on building work in general, and loft conversions in particular, is as confusing as any other area.

But we’ll give it a go.

Building work classed as maintenance or conversion is chargeable at the full rate of VAT – whatever that may be at any given time.

Of course this will have a significant effect on the bottom line when it comes to working out the final loft conversion price though there are one or two exceptions to the full rate.

Work on new builds does not attract any VAT charges whatsoever and conversions to listed buildings, if allowed by the planning department, are also charged at 0%.

There are also different rates of VAT should you be building a loft conversion in a property that you have just acquired if it has previously stood empty.

If the property has been empty for ten years then there is no VAT chargeable with the rate set at just 5% if the house has been empty for more than three but less than ten years.

Getting around VAT

Not suggesting anything illegal here but if you are using teams of contractors for different jobs, rather than one company to do everything, then those individual builders may not be registered for VAT.

By carefully picking your contractors it may be possible to reduce the VAT on a total loft conversion price.

A specialist loft conversion company will need to charge VAT though arrangements may be made to pay the VAT on a staggered basis throughout the build or even to defer the VAT until the job has been completed.

Unfortunately, some VAT is inevitable and you must be very clear from the outset the rates that you will be charged and for what jobs.

Builders are very good at changing the subject when VAT is mentioned but, for your own peace of mind, it is imperative that the situation is clarified, in writing, before any work is done.

Failure to take VAT into account can have a severe impact on your budget so ensure it is sorted out at the very start and not left to add a nasty surprise to the final amount that you are charged.

Why convert the loft?

We’ve discussed how much a loft conversion will cost – so is it worth doing and why would you take on such a project in the first place?

With more and more homes being thrown up around the country, it is becoming more and more difficult to find a sizable property. The problem is that housing companies are trying to go for quantity over house size and yet, so many of us need more space. Even if you live in a larger property or an older one with bigger rooms, there is still a call for additional usable space. A loft conversion is a fantastic way to achieve that.

Why converting your loft is a good option

Moving into a new home is filled with excitement and many see it as a fresh start. However, when you have been in a house for a long time, it becomes a home and you may not want to move to another property just for the sake of additional space. This is the case for many people who feel as though they are settled but with a growing family, they may feel as though there aren’t many options but to upsize.

Doing this within your own property and converting your loft will allow you to spend many more happy years in your home as well as coming with a variety of other advantages.

Add value to your property

The price of property has risen significantly over the last few decades and while there are ebbs and flows, this is something that will continue. However, how much your property increases in value will depend on how well-maintained it is and what features you add to it.

It is estimated that installing a professional loft conversion could see the price of your home skyrocket by as much as 20%. This increase could be even greater if your home is in a very sought after location so if you’re looking to make wise investments, it’s a no brainer.

A versatile space

Many people instantly assume that people who opt for a loft conversion are doing so to add an extra bedroom to the property. While this is a perfectly viable way to use your new space, a loft conversion doesn’t have to only be used this way.

When you convert your loft, you are creating a very versatile space. If it is big enough, you may put in a partition wall and have two usable rooms. Whether you choose bedrooms, a den, an office or even a games room, you’re free to use the space in a way that suits you.

What’s great is that you are free to design a space to fit your needs. If you need an additional bedroom, you might also decide to add an en-suite, giving you an entire guest area or another room for a family member. When doing this, you can factor in every requirement and produce a bespoke layout that you’d never be able to achieve by simply buying a new home.

And if all of that wasn’t enough, you must consider that your loft conversion will grow with your family. You may initially install the space as a playroom for your children but as they get older, they may appreciate it as a bedroom away from the rest of the house. Once they leave home, you’ve got yourself a home office.

Cheaper than relocating

The cost of moving house, according to Barclays Bank, currently sits at just below £9000. That’s a lot of money especially when you consider that, to upsize, you’ll likely need to take out a larger mortgage on top of this.

By comparison, installing a loft conversion is much more affordable and yet will still bring some excellent revenue when it comes to selling your home. Now, a loft extension could cost anywhere between £20,000 and £63,000 depending on what you want and the size you’ll go for. That may sound like significantly more than the £9000 for moving but when you also factor in that the difference between a three and four bedroom property in the UK could potentially be double depending on where you buy.

It’s less time consuming

If you have ever purchased a property, you will be well aware of the fact that things don’t always go smoothly. On average, you would expect it to take anywhere between three and six months to go from making your initial offer through to completion. However, there are a lot of things that might crop up along the way meaning that moving can sometimes take a year or more.

But did you know that building a loft extension takes just eight weeks on average. Hiring an experienced and competent contractor will ensure that the job gets done to the absolute best standard in the shortest amount of time. But even at a maximum, you still wouldn’t be looking at the same length of time as it would take to relocate.

What’s more, you will find that having a loft conversion is a lot less hassle than moving house. While you will need to work closely with your contractor, they will be doing most of the hard work. It is merely up to you to oversee the project, explain what you would like and give the go ahead on any additional work that may need to be done.

When you hear the term ‘loft conversion,’ it is easy to want to go running for the hills. After all, most people assume that this is a massive undertaking that will seriously break the bank. But all things considered, installing a loft conversion is one of the best ways to give you more living space as well as adding some serious value to your home. It works out much cheaper and when you do come to sell your home down the line, you’ll make a nice little profit!

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