How much value does a loft conversion add?

“The typical value added can be around 10% to 20% if creating a new bedroom and ensuite with a loft conversion, explains architect George Omalianakis from GOAStudio architects. He adds that the value increase will depend on the floor area you add to your property and where your property is.”

Homebuilding & Renovating

Sam Webb, March 2023

We were asked to advise homeowners as part of Sam Webb’s article on Homebuilding & Renovating in March 2023.

The key question was about how much value does a loft conversion add however when it comes to considering a loft conversion project there are always additional considerations and things you need to know above before you are able to make a decision on whether to proceed with your project or not.

In addition to the quotes that appeared in the article George also prepared a more comprehensive guide on loft extensions, on how much value does a loft conversion add, and the key things you should know if you want to maximise the value added to your property.

 Homebuilding & Renovating | How much value does a loft conversion add

You can read the full article here: How much value does a loft conversion add — plus room types that add the most value
By Sam Webb published March 01, 2023

And below you can read the actual guide we prepared for this article that includes full advice for homeowners who are considering to extend their property.

For an architect’s guide on roof extension you can read more here: Roof extensions London architect guide.

And if your property is suitable for a mansard roof extension you can read more here: Mansard roof extensions
London architect guide

CONTACT USif you have a project in mind and you need specific advice on your requirements.

Roof extension Chiswick Hounslow W4 – Bathroom by GOAStudio architects scaled Homebuilding & Renovating | How much value does a loft conversion add

What basic checks should you make to see whether a loft is suitable for converting?

1. Check the current headheight in your loft space.
Rule of thumb: the higher the floor to ceiling height (to the underside of the ridge) the more the useful space you can add to your loft with an extension.

2. Check if your property has retained its Permitted Development rights.
Rule of thumb: Permitted Development Rights will allow you to fully extend to the sides and to the rear of your roof, and to a limit of a 40cubic metres for terraced properties and 50cubic metres for semi-detatched and detached properties. This will translate for a much more generous room sizes when compared to the typical allowances under the planning rules of your local authority. Typically flats and properties in a conservation area have no Permitted Development Rights which means that in this case your local authority will only approve a roof extension around 2/3s of the height of your roof and 2/3s of the depth of your pitched roof.

3. Is your roof a butterfly (V-shaped roof)?
Very different rules apply for butterfly roofs and you might be able to add a full storey to your property by adding a mansard-type roof. This applies to both houses and flats, and irrespectively of whether the property is in a conservation area or not.
Rule of thumb: Check the properties on eitherside of your property and on the same side of the street. Out of a row of 10no. properties, how many of them have had mansard roofs added to them? If the answer is more than 5no. then it is likely that your local authority will accept the addition of a mansard roof extension to your property too. If the answer is less than 5no. then obtaining an approval will be more challenging.

4. Can your roof be extended?
Check with an architect or a building professional about the feasibility of converting your loft and extending your roof. Not all lofts can be converted, not at least without having to lower the ceiling of the floor below which will add complexity and costs that could result in making your project unfeasible or uneconomic.

What you can achieve will vastly vary depending on your property and on your area and if you want to maximise what you can achieve for your home please speak to a professional who will be able to achieve what is right for you and to your property.

“For houses with a good mix of bedroom sizes, a loft conversion allows the opportunity to create a grand master-bedroom area with an en-suite and walk-in wardrobe areas, and if the space allows it an additional seating or kitchenette area to create a top floor ‘hotel suite’ type of area at the top of the house,” he explains.

“Another popular and valuable arrangement is the creation of a larger master-bedroom area while retaining enough space for a separate room in the loft that can be used as a study or a gym space. This second space does not need to be large and can be used flexibly.”

George Omalianakis

GOAStudio London residential architecture

“As a rule of thumb you can budget for around £1,750 per square metre for a standard loft conversion, according to architect George Omalianakis, giving a cost range of around £40,000 to £60,000 for medium-sized loft conversions.”

George Omalianakis

GOAStudio London residential architecture

How much value does a loft conversion add? Obviously it depends but is there a broad %? How do factors like the below add value?

The value added will depend on the floor area you add to your property and where your property is across the country.

Regional and local factors, whether you are in the countryside or the city, will substantially affect how much value a roof extension adds to your property.

Have a chat with your local estate agents will be able to offer you expert advice on this. Typical value added is around the 10-20% mark if you can create a new bedroom + en-suite area in your loft, something that is achievable at most times for typical 2-3bed properties with Permitted Development Rights and a min headheight in the loft of around 2.3m.

Loft conversion size

The key thing to say here is that if you get a chance to convert your loft then always go for the largest roof extension and loft conversion you can get planning approval for.

The law of diminishing returns applies and once you have added a room or two the additional space will add less value / sqm added.

However because the relative £/sqm cost of adding this extra space is low and this means that if you commit to the project then it makes sense to maximise the area you can add to your property rather than just add a little bit to your loft space.

Once you know what is the maximum you can add then it becomes a question of how best to use this extra space and which arrangements and type of rooms will give you the best value and that will best meet your requirements.

The type of room being added

1. For houses with sufficient number and a good mix of bedroom sizes a loft conversion allows the opportunity to create a grand master-bedroom area with an en-suite and walk-in wardrobe areas, and if the space allows it even an additional seating or kitchenette area to create a top floor “hotel suite” type of area at the top of the house as a special room for mum and dad.

2. For a growing family a larger loft area offers the opportunity to create 2no. bedrooms areas and a separate bathroom that can be accessed either separately off the staircase landing or directly shared from the two bedrooms. Top tip: In this case, and to avoid arguments about who of the kids’ bedroom is larger, it is always wise to keep the size of the two bedrooms roughly the same.

3. Another popular and valuable arrangement is the creation of a larger master-bedroom area while retaining enough space for a separate room in the loft that can be used as a study or a gym space. This second space does not need to be large and its value is in that it is a separate space that you can use flexibly when you need it.

Whether you lose any space for adding stairwells (ie lose a bedroom to gain a bedroom)

Sometimes you might need to sacrifice some space on the floor below to add the new staircase to the loft space and this is inevitable.

Designing a new staircase is like a three-dimensional puzzle and the new staircase will need to comply with the current Building Regulations in order that it is not too steep or too narrow. A good designer will minimise the impact of the new staircase on the floor below and locate the staircase where it allows you to maximise what you can achieve at the loft level.

Think of it as a Venn diagramme and the new staircase will need to be exactly in the middle of the two floor plans and exactly at the right place for everything else to work well around it.

You rarely get to lose a bedroom to gain a bedroom and when you do then the new bedroom tends to be much larger than the one you lost. In the vast majority of cases you will be able to gain a room or two by converting your loft space.

How much will my loft conversion cost? Again, it depends but here are some ballpark figures for roof extensions across the London area.

This will vary depending on the size of the extension, the type of the extension, the type of the associated structural alterations required, the type of the internal + external finishes, the specifications of the glazing and any Juliet balcony features, the type of the staircase, and where you are in the country since there are always local and regional variations to the cost of labour and materials.

As a rule of thumb you can budget for something like £1,750/sqm added for standard roof extensions.

This will result to a range of around £40-60K +VAT min for medium sized roof extensions to double pitched roofs and around £60-90K + VAT min for much larger mansard type roof extensions to butterfly (V-shaped) type roofs.

The chances are that the final costs will be higher or lower depending on your requirements and the type / size of your loft conversion project.

Do you need planning permission for a loft conversion?

If you do not extend the roof profile and you only use the internal space available to your loft then you will not need planning approval. You might still need Building Regulations, Freeholder and other approvals.

However you might still need to obtain planning approval for any rooflights you add to your loft.

Under specific circumstances you can extend your roof as part of converting your loft without obtaining planning approval and you can do this under Permitted Development.

There are limitations to Permitted Development Rights, for example they apply to house but not to flats. It is recommended that you still apply to obtain a Certificate of Lawfulness to confirm your Rights and to make sure your extension is Lawful. In most cases the Permitted Development planning route will give you the largest possible extension to your loft space.

If Permitted Development Rights do not apply to your property, and for mansard-type roof extensions to butterfly (V-shaped) roofs, then you need to apply for planning approval to your local planning authority.

Contact your local planning authority for advice, search for planning policy guidelines to see what your planners are likely to approve for your property, and speak to architects and design professionals for further advice on your home project.

Extra bits you will want to know about

1. Rooflights – do not miss the chance to introduce top light to the loft room and the staircase, this is an opportunity to create an outdoors feel to your internal spaces.

2. Lower headheight areas – take advantage for extra storage, a kid’s play area, indoor plants under rooflights, or just cosy enough for a double bath.

3. Under eaves areas – take advantage of this extra space and make best use of it with specially designed fitted cupboards, wardrobes and shelving.

“George Omalianakis says the final cost will of course vary depending on the size and the type of the extension, the associated structural alterations required, the internal and external finishes, the glazing, the type of the staircase, and where you are in the country since there are always local and regional variations to the cost of labour and materials.

“The chances are that the final costs will be higher or lower depending on your requirements and the type and size of your loft conversion project,” he adds.”

George Omalianakis

GOAStudio London residential architecture

Contact us

Do you live in London? Do you look to carry out home improvement works? Then the chances are that your home is of traditional construction and you need to make sure that your architect understands that.

What sets us apart from other residential architects is that we have the relevant qualifications, knowledge, skills and experience to work with older and traditional buildings like yours.
We understand the chronology, building styles, age and characteristics of traditional (pre-1919) buildings.
We also understand the condensation risks when you carry out any building work, which happens because the thermal performance and energy efficiency of traditional (pre-1919) buildings is affected by extensions, repairs and retrofit refurbishment works.
This is what we are passionate about and this is what we are experts in.

Contact us with your ideas and your requirements and we will get back to you with advice on how we can assist and the next steps.

Since 2009 we have designed for some amazing transformations of properties across London. As expert London residential architects we are often asked to help homeowners create their “forever” home or a home they simply look to grow into until they are ready to move again.

We know that home can mean many different things to different people and we also know that properties in London come with their own unique character, challenges and potential. We enjoy the journey and we enjoy finding potential in every single project we are involved with.

GOAStudio London residential architecture media opinion publications 2 Homebuilding & Renovating | How much value does a loft conversion add

GOAStudio London residential architecture and interior design is an award-winning practice, specialising in architectural services for residential projects across London.

As your local residential architect our team aims to provide a friendly and professional service for your home project.

Our approach is based on carefully considering the particular aspects of each scheme before coming up with a creative way for you to instil your unique stamp on what we do and how we do it. 

Royal Institute of British Architects (RIBA) and Architects Registration Board (ARB).

BOROUGH SPECIFIC ARCHITECT AND PLANNING GUIDES FOR YOUR HOME PROJECT

Your local Council will have in place design and planning requirements for your home project and you will need to obtain planning approval for a wide range of extensions and alterations to your property.

When you get in touch we will offer you detailed advice about what is likely that your Council will approve and in the meantime we have prepared the following architectural and planning guides that include extracts of the relevant planning policy and examples of our projects in our Borough.

Barnet residential architect and planning guide, Camden residential architect and planning guide, Enfield residential architect and planning guide, Hackney residential architect and planning guide, Hammersmith Fulham residential architect and planning guide, Haringey residential architect and planning guide, Hounslow residential architect and planning guide, Islington residential architect and planning guide, Kensington and Chelsea Conservation architects, residential and planning guide,  Lambeth residential architect and planning guide, Lewisham residential architect and planning guide, Newham residential architect and planning guide, Redbridge residential architect and planning guide, Richmond residential architect and planning guide, Tower Hamlets residential architect and planning guide, Waltham Forest residential architect and planning guide, Wandsworth residential architect and planning guide, Westminster residential architect and planning guide

We provide architectural services in the following London Boroughs:

Read our design, planning, and architectural guides above if you seek advice for your project.

We can help you with these home extensions and renovations:

See our guides above for ideas, inspiration and architectural advice for your home project.

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We specialise in

  • Greener homes
  • Retrofit and energy efficiency for older and traditional buildings
  • Conservation areas
  • Listed Buildings
  • Homeowner architectural services
  • Developer architectural services

RIBA Chartered architect services

CONTACT US

GOAStudio London residential architecture limited, 86-90 Paul Street, EC2A 4NE, Hackney

GOAStudio London residential architecture limited, Chestnut Avenue South, E17 9EJ, Waltham Forest

t: 0203 984 3005
e: george@goastudio.co.uk
e: media@goastudio.co.uk

 

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