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loft conversion cost

Loft Conversion Cost – Price Comparison UK 2021

In reality, there isn’t a one-size-fits-all approach for understanding the full breakdown of a loft conversion cost.

With that in mind, you’ve come to the perfect place. The Loftera team are on hand to explain the full breakdown of your loft conversion, and offer our guidance on which option is best suited to your needs.

You’re absolutely doing the right thing in researching ahead of making your final decision. It’s a serious commitment, and one that we are determined to make sure you get right.

Keep on reading to find out the loft conversion costs for varying projects.

Loft Conversion Cost: A Breakdown

Your loft conversion cost can range from £15,000 up to £70,000. We know, that’s quite a variation, so it is essential that you are confident with the decisions that you make. Each individual decision will determine where in that range your conversion sits.

However, the main factor in terms of impact of your overall cost is the design itself. Allow us to explain.

Rooflight Loft Conversion

The cheapest option available is the rooflight loft conversion. Here, rooflight windows are installed to allow for natural sunlight into the loft. Flooring, insulation, plaster boarding and fitting of lighting all add into the overall cost, although the alterations involved are generally minimal.

Basic doesn’t necessarily have to be a bad thing. Sometimes, less is more. If you aren’t looking to install extensive electrical work or plumbing, a rooflight loft conversion may be the ideal choice for your home – particularly when you consider the average price is between £15,000 and £25,000.

Dormer Loft Conversion

A dormer loft conversion consists of creating a boxe-shape structure that replaces one of the slopes of a roof. The final result is brilliant in that it allows for full-sized windows and furniture in the flat-roof space. The rebuild of one roof pitch means that a dormer loft conversion costs that bit more than a rooflight conversion, but the flexibility is unquestionable.

You’re looking at between £25,000 and £50,000 for a standard dormer loft conversion, while an L-shaped dormer that has a corner can increase your overall price.

Hip to Gable Loft Conversion

You may never have realised just how lucky you are to live at the end of a terrace. Or perhaps you have, and that is the exact reason why you purchased your property in the first place.

Of course, if you live in a detached house, you have the flexibility on either side of your property.

The roof slope is completely replaced with a vertical brick wall and is combined with a dormer conversion to maximise the space. A brick gable wall is built, as opposed to a stud wall, which naturally bumps up the price.

The average price of such a project in the UK ranges from £30,000 to £60,000.

Mansard Loft Conversion

Finally, a mansard loft conversion creates a flat roof space and can even create an additional storey on top of the existing building.

Such a project will always require planning permission and is without question the most expensive option out there, at between £40,000 and £70,000. However, the final design can be stunning and is very much an option that can be explored at Loftera.

Heating a Loft Conversion

Extensions, understandably, do tend to increase the heating requirements of a property. However, you might be surprised to hear that a loft conversion can often improve the overall energy efficiency of a house given that they are so well insulated.

If you are set on the idea of additional heating in your loft, radiators are a popular option. Some people opt for underfloor heating, or even both.

Insulation in a Loft Conversion

The best way to insulate a loft conversion is via a cold roof method. In doing so, the space between the rafters is filled with 70mm thick slab foam, allowing for 50mm spacing between the roofing felt and insulation.

On the inside of the rafters, 30mm foam is also added, giving a total of 100mm of insulation.

The roof section requires 300mm of mineral wool insulation or 150mm of slab foam insulation, such as Celotex.

It is essential that the insulation between the walls and the roof remains consistent. In order for this to be the case, a 100mm quilt is inserted in the internal partition walls with plasterboard then attached to cover.

The floor joists will also be fitted with insulation, allowing for a fully heated loft extension.

Sounds great, right? We are experts in loft insulation and consider it very much part of the overall package.

Stages of a Loft Conversion

Wouldn’t it be nice to pick out a design of lost conversion and then, after a click of the fingers, it is completed?

We can take a lot of the hassle out of the building work, but there are different stages to the overall job before completion.

Planning Costs

A job of this size requires comprehensive plans to be drawn up by a qualified architect. They will be able to map out the exact design and the changes that are required before completion. Taking into account all of the necessary structural alterations, an architect will be able to make all the necessary calculations and ascertain how much the building work itself will cost. You can usually look to pay around £1,000 for this service.

Planning Permission Costs

For some of the aforementioned smaller loft conversions, planning permission won’t be required. This is because the changes will count as permitted developments. However, for mansard loft conversions and some hip to gable alternatives, planning permission may indeed have to be applied for. Expect to pay planning permission fees of £172 in the UK.

Building Regulation Costs

No matter whether planning permission is required or not, your conversion will absolutely have to be inspected by the building regulations department or your local authority.

Fire safety, access and floor strength are just some of the areas that will have to be assessed. Plans for this type of inspection can cost between £400 and £800.

Should your loft extension impact any adjoining properties, such as a terraced house or semi-detached building, you’ll require a Party Wall Agreement.

Put simply, your neighbours will have to agree to the work taking place, so you’ll want to be extra nice to them! You are liable for their surveyor costs and any damage to their home which may occur as part of the job. Damage like this is of course unlikely, but such eventualities have to be covered for building work of this size.

Building Work Costs

You’ve had your plans mapped out and approved, now it’s time to get down to the nitty gritty of the building work itself.

More often than not, external work will take place first with the use of scaffolding. Later on in the job, access will need to be granted via the property itself and the floor will be strengthened at this point. The interior walls will be fitted, roof altered, dormers constructed and then the insulation process can begin.

Essential features such as a staircase, windows and electrics will be fitted, with the option of plumbing if a toilet is being installed.

Once the final inspection has taken place and approved, the decoration can begin. All in all, the building work is where the bulk of the cost is spent.

Additional Costs

A slate roof tends to cost more in terms of alterations than concrete roof tiles. If your property is a bit older, usually pre-1960s, it will likely be bult with a frame. Replacing these frames can take more work and, as a result, increase the overall cost of your loft conversion.

Traders Required to Install a Loft Conversion

As you may have gathered, or are probably already well aware, building a loft conversion is far from a one man job.

There are multiple expert tradesmen that will need to pull together to ensure that your dream loft conversion is completed to the standard that you require.


All of the above building work will need to be performed by, you guessed it, a builder. They’ll be able to paint a clear picture of what is structurally possible and fit the sound proofing and insulation. A little pointer is to ask your builder what type of insurance they have.


The beautiful natural sunlight that the fitted windows will allow for is fantastic, but you’ll absolutely need electrical lighting fitted, unless you only plan on using your loft in the daytime. A qualified electrician will be able to provide a BS7671 test certificate once completed to allow you to pass building regulations.

Window Fitter

About that natural sunlight. You’ll require a glazier to come and advise on the best place to have your new windows fitted. Once decided, they’ll have to fit them, making sure that the correct standard of double glazing is followed to allow for the necessary noise proofing, insulation and security standards.

Heating Engineer

We live in England, guys. Heating is an absolute necessity, unfortunately. A heating engineer should, of course, own the process of installing your heating options. They should also advise on where best to fit any radiators so that the heat adequately reaches the rest of the conversion.

Have you considered solar panels? If your conversion is on a larger scale, these may be the ideal option for your property, saving you money in the long run.


Larger conversions may benefit from an en-suite, particularly if the new room is being used as an additional bedroom. A sink, toilet and shower may be required in this instance.


Often known as the jack-of-all-trades, a joiner will be essential to the completion of your loft conversion. The chances are that you’ll require new ceiling joists given the fact that a lot more people are going to be passing through. Anyone that already has a loft conversion will be only too aware of the awkward shape that the design can leave them in. A good joiner will be able to advise on the best storage solutions for your situation.


With any new internal building work, you’ll want to be sure that the walls are plastered as smoothly as possible so that any painting or wallpapering can be done to the required standard.


Larger loft conversions such as mansard and hip to gable will require scaffolding in order for the building work to take place.


If you’re planning on a bit of DIY work, painting may well be the best area to try your hand. Failing that, a painter and decorator will be the last port of call to put the finishing, and often most visible, touches on your loft conversion.

Of course, all of the above tradesmen come with a cost. They are essential to the work being completed, but you’ll want to know how much they are going to cost.


Average Hourly Rate





Window Fitter


Heating Engineer












Loft Conversion Flooring

You’ll want your brand new loft conversion to look as comfortable and cosy as possible. Making the correct choice in terms of flooring goes a long way to ensuring that the new room feels exactly how you want.

There are multiple options to choose from, each with different costs involved:


Average Cost (Per M2)









Top Tip: How to Reduce the Overall Cost of a Loft Conversion

As far as we’re concerned, the best way to ensure that your loft conversion costs are kept to a minimum is to hire experienced and reliable experts who are committed to seeing the job through from start to finish.

That’s exactly what the team at Loftera can provide. We have been perfecting our craft for a number of years and are proud to provide our famous service to the people of Merseyside and beyond.

A job of this size, whether you are opting for a mansard or rooflight loft conversion, is bound to encounter one or two snags along the way. We’re used to that, and are beyond confident in our ability to iron out any such issues.

Location, Location, Location

In general, loft conversion prices tend to go hand in hand with the property market of the area in question.

Often, this difference is down to how densely populated an area is. In a busy city area, there is often little or no space for parking, rubbish skips, scaffolding, machinery. This does increase prices.

Naturally, a higher cost of living will coincide with higher salaries for works and increased daily rates. It goes without saying that this will all result in a bumper final price. Delivery and material costs should be factored in also. The size of a delivery vehicle, or distance that it needs to travel, will alter the final cost.

As we are sure you are now understanding, there are many factors to take into account to keep in mind in order to ensure that your loft conversion cost is kept to a minimum.

Reasons for a Loft Conversion

There are numerous reasons behind why people opt for a loft conversion in their home. One of the main benefits is that it adds value to your house.

Sure, if you’re putting this much time, effort and resources into such a big build, the last thing you are likely thinking of is selling your property.

However, it is always nice to know that your house has increased in value, it puts you in a strong position in the market at a later date if required.

On the topic of moving, if you are considering upgrading your home, perhaps because you are due to increase your family size, a loft conversion is a much less expensive way of doing this.

Adding natural sunlight into your home is never a bad thing. When building a new loft conversion, the choice is yours on where or how many windows you fit. We would advise to go for as many as possible, as allowing natural light into your home allows for a warm feel, and can save costs on electricity bills.

We spoke earlier about the insulation required when building a new loft conversion. It is no secret that the newer the insulation, the better it works. When fitting brand new insulation, you will be improving your insulation and making your home more energy efficient.

Growth is always a plus, right? In life and in your property. Building an extension or a conservatory is fantastic, and done right they can be stunning. No matter how good the work is though, there is one issue that is unavoidable – you lose space. The last thing most of us want is to lose garden space, those summer days in the back garden are priceless, and building outwards, in the shape of an extension or conservatory, reduces precious space.

In theory, although perhaps not quite literally, when building upwards, you can go as high as you like. We wouldn’t recommend attempting your very own mini skyscraper, but the point remains. When building upwards, like with a loft conversion, you don’t lose any space. You only add.

Potential Issues With a Loft Conversion

Of course, any project of this size will face one or two issues. Please don’t panic, it is perfectly normal, and that is where experts like us come into play.

Party Wall Disagreements

Those years of making friends with your neighbours can really pay off when embarking on a job of this size. In reality, your neighbours are much more likely to agree to your loft conversion if you are on good terms.

Our advice would be to speak to your neighbours before any sort of work begins. Should you anticipate any problems, be sure to get a party wall agreement in place at least two months before starting.


Older properties may well come across asbestos in a loft space. There is no way to avoid this. However, you are best to have a survey carried out before committing to any building work so that this issue can be dealt with properly.

Out of Place Furniture

We are sure that many people reading this will be experts in interior design. Your choice of staircase up to your loft can limit you in terms of the size of furniture items that you can take up there.

Speak with the contractor early on. There is a chance that you may be able to have the furniture taken up early on before the banister and door frames are built. If you don’t ask, you don’t get.

Planning Permission

There is so much to remember, that it is only natural that one or two items will be missed. Make sure that applying for planning permission isn’t one of them.

Failure to do so can result in a hefty fine, which just isn’t worth it considering that the local council can provide a notice of lawful development certificate for between £100 and £400.

Frequently Asked Questions

How Much Value Does a Loft Conversion Add to My House?

On average in the UK, a loft conversion increases a property value by 22%. This can fluctuate depending on the quality and size of work, and the area where the work is being carried out.

Will a Loft Conversion Impact My Council Tax?

In general, council tax bands are only reviews when a property is being sold, or if the tenants ask for a review. If neither of these take place, a loft conversion being built should have no impact on your tax.

I’m Converting the Loft Myself. Do I Need Insurance?

If you are planning on carrying out the work yourself, congratulations! You are set to save yourself an awful lot on your loft conversion cost. However, it is still worth taking out insurance. If nothing else, this covers you in case of damage to your property or injury to yourself.

As you can see, there is an awful lot to take in when committing to a loft conversion. Your first port of call should be to contact the Loftera team on hello@loftera.co.uk or call us on 0151 317 5013. We look forward to hearing from you.