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Loft conversion: where do I start?

Thinking of a loft conversion in your home to add more space and value? To help get you started, we take it from the top with pointers on design, planning rules, building regulations, through to handling the neighbours and finding the right company to undertake your loft conversion.

Why do a loft conversion?

A loft conversion can add a significant amount of money  – up to 20% – to the value of a property. Many families choose to convert their loft area as a means of obtaining more space without having to endure the costly and stressful process of moving home. Work taking place in the loft can also be less disruptive than, say, a major extension to an existing living space.

But be careful not to outgrow your road. If you invest too much and extend too far you’re unlikely to see a return on your investment.

Is my loft a useable space?

You’ll want to start by assessing whether your roof space is suitable for a loft conversion. Most are, but there are three main things to check:

  • Internal height. Measure from the top of the ceiling joist to underneath the ridgeboard in the apex. It needs to measure 2,500mm to suitably convert.
  • Roof pitch. Measure the angle of the roof. The higher the pitch angle, the higher the central head height is likely to be.
  • Footprint. As a minimum rule of thumb, internal rules should measure 5,500mm side to side, inclusive of chimney, and 7,500mm front to back.

How will I use the loft space?

Once you have roughly established your home is suitable for a loft conversion, think about how you would like to use it; perhaps an extra bedroom with en-suite bathroom, or maybe a den or playroom for your growing children. How about a space to relax or study away from the rest of the family?

Or it could be a multi-purpose room with a combination of uses, such as extra living space which doubles as guest accommodation. If you are going to include a bathroom, will it be a shower room or will there be space to include a bath? When you are thinking about planning a bathroom in a loft, remember to leave plenty of headroom.

Also think about storage, as built-in space can often be included, especially in the eaves.

When looking at the floor plan don’t overestimate the space you will get. You may have angled ceilings which restrict movement and the type of furniture you can have. By necessity most domestic loft conversions offer useable space of cosy dimensions, best suited to sleeping, play or office space.

Want help designing your loft conversion? Find local architects with our find an architect tool

Can I convert the loft myself?

The installation of a loft conversion is a complicated process, which may involve your planning department and certainly require Building Regulations sign-off (see below).

Whilst it is possible to attempt a DIY conversion, with expert help for some of the trickier aspects, the large amount of work involved often results in many people choosing to contract a specialist loft conversion company to undertake the task.

Use our Checkatrade tool to find local loft specialists, read reviews, view examples and get in touch for a quote.

Who should I use to do my loft conversion?

There are a few options:

1. Appoint an architect/technician or building surveyor. They will prepare drawings and designs for your proposal, obtain the necessary approvals, and if required, they will also help you find a suitable builder and manage the project for you.  See do I need an architect? and find a local architect.

2. Appoint a specialist loft conversion company. These companies offer a one-stop shop for loft conversions: their design department will prepare the necessary drawings and obtain the necessary approvals and their construction departments will translate the designs into reality.

3. Use an experienced builder. Some builders have experience of loft conversions and may well be able to offer you a package similar to the loft conversion companies.

Ask neighbours, friends or search online to find a trusted architect, loft conversion company or experienced builder for your project. Don’t forget to get three quotes and make sure they visit the site and quote based on accurate measurements. Knowing how you want to use the space will be essential to getting a few good quotations.

Ask your contractor how they plan to minimise dust and disruption during the conversion and how they will protect your home from the risk of water damage should works affect the existing roof before you sign up.

Find a rated local contractor to help you with your loft conversion project with our find a tradesman service

Do I need planning permission and building regulations for a loft extension?

Planning permission is not normally required, unless you are extending the roof space or exceed specified limits e.g. any dormer is higher than the current highest part of the roof or you live within a conservation area. It’s best to check permitted development guidelines with your local planning department to understand what you are allowed to do.

Building regulations apply to loft conversions to ensure, for example, that the structural strength of the new floor is sufficient, the stability of the existing structure is not endangered, there are safely designed stairs to the new floor and reasonable sound insulation exists between the conversion and the rooms below.  There are also fire safety regulations with which you may need to comply.  Read our guide Do I need a Structural Engineer?

Do I need a party wall agreement for my loft conversion?

If you are putting a loft extension on a detached house and there is no shared wall with the neighbour, then no.

If you live in a top floor flat, terrace or semi-detached house, then yes you are likely to need a party wall agreement with your immediate neighbours. This is because building work typically involves changes to shared walls, chimneys and roofs that could potentially damage adjoining properties. The Party Wall Act 1996 provides a way of giving adjoining owners notice of works and protecting all parties. Find out whether you need a Party Wall Agreement and let us help you find a party wall surveyor.

Loft conversion costs 2022

The typical loft conversion cost in the UK is around £40,000, according to Checkatrade. However, this price can vary considerably depending on the type of loft conversion, the size, number of dormers, the complexity of the project and your property’s location.

A Velux loft conversion will cost around £27,500, while a bungalow loft conversion will cost in the region of £75,000.

Types of loft conversion

The most common types loft conversion and average costs are as follows:

  • Velux – the least expensive option which involves installing velux windows to the roof. Average cost £27,000
  • Dormer – the most common option which involves a small flat roofed extension with a window. Average cost £45,000
  • Hip to gable – this expensive option involves altering the shape of your roof structure to gain space. Average cost £55,000
  • Mansard – the most extensive option, a Mansard extension involves the whole shape of the existing roof is changed. You end up with an essentially flat roof and vertical outer walls. Average cost: £57,500. 
  • Bungalow loft conversion – these are generally larger in area than regular houses and so come in slightly higher. Average cost: £75,000.

Loft conversion cost calculator

The above costs are averages in order to give you an estimate of the costs involved. Online loft conversion cost calculators sound like a good idea but similarly will only give you averages. The best thing to do to get a real idea of the costs involved is to approach firms in your area, book a consultation and get a quote.

Use our Checkatrade tool to find local loft specialists, read reviews, view examples and get in touch for a quote.

Cheapest loft conversion ideas

We often get asked for the cheapest ways of doing a loft conversion. There are a number of factors which impact the costs. In order to reduce the costs of your loft conversion you could:

  1. Work with the existing roof line. If you have the space in your loft for a conversion and what you want to use the space for, then avoid altering the roof line to create further space. Changing the roof structure and adding more windows, rather than just adding velux windows to the existing roof, will increase the costs significantly.
  2. Avoid changes that require planning permission. Loft conversions can be completed within permitted development rights. By doing so you will avoid the time and costs involved in seeking planning permission. Check what parameters you need to abide by to avoid needing planning permission.
  3. Plan around existing plumbing. This applies to all building works. Moving plumbing across the room to fit with a plan you have might deliver the best aesthetic but can also add to the final bill, as well as time the project takes to complete.
  4. Choose your trades carefully. A loft conversion firm is the most expensive option but might be the most cost effective in the long run. Or, if you have a clear idea of what you want to do then a builder may be right for your project. Whichever route you take, remember to get at least three quotes and carefully compare them. Our guide Going out to tender for builder’s quotes may be of help.

Loft conversions on leasehold flats

If you own a leasehold flat you are unlikely to own the loft space. So if you want to extend into the loft, you will need to obtain all the legal rights and consents you need from the freeholder (even if you have a share of freehold) before you do anything else.

Even if your lease stipulates that you do own the loft space, most leases do not allow structural changes without prior consent.

If permission is granted, the landlord/freeholder is also likely to want to see your loft extension plans to ensure the changes  will not have an adverse effect on the building and will want to see any planning permissions documents have been obtained and building regulations sign-off of the works. Read more about how and when to get your freeholders consent.

Possible pitfalls for your loft conversion project

Stairs to a new loft conversion can prove difficult. There are regulations to abide by, such as the minimum two-metre head clearance under and above the stairs. Fire exits are not needed in a home, as they would be in a commercial building, but means of escape should be considered and fire prevention/detection should also be incorporated.

Plumbing will normally be a case of adding on to the existing system; in certain cases after tests and surveys are carried out, the system may require upgrading,

The insulation properties of your home may need to be improved, or certification for the work might not be granted. Building control will always inspect this to make sure the standards are met and that energy-saving measures are at a maximum.

With a little careful planning and right designs and contractor in place, however, your loft conversion should go smoothly. It’s worth having a small contingency fund in place in case of unforeseen problems or overruns, but in general a loft conversion will be highly rewarding, adding usable space and value to your home.

Informing your insurance company of building work

Don’t forget to inform your insurance company about building work before you start. A loft conversion could involve opening up your home to the elements and increase the chances of  you needing to claim. You’ll want to make sure you have sufficient cover.

A loft extension is also likely to change the original value that you have the home insured for. You will need to inform you insurance company and check you have sufficient buildings and contents insurance.

Summary of key steps when getting a loft conversion

In summary, when planning your loft conversion project:

  • Do an initial assessment of your existing loft space.
  • Think about how you want to use the loft space.
  • Consider who you would like to do the work and get at least three quotes based on measurements.
  • Review costs and discuss them with your chosen contractor so you understand all the elements.
  • Pre-empt the pitfalls with your chosen contractor.
  • Consider the planning, party wall and building regulation requirements of your conversion.
  • Get a contract in place for the works with your contractor/builder/loft conversion company and architect so you know who is responsible for what.
  • Once you are ready to commence works, be sure to inform your insurer.

Use our Checkatrade tool to find local loft specialists, read reviews, view examples and get in touch for a quote.

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