Loft Conversion: A Step-by-Step Guide on How to Convert a Loft

Most lofts are unused spaces. Typically, they are just a place to store stuff we rarely need, such as Christmas decorations.

But if you require extra room in your house, a loft conversion could be a great solution. Not only could it add additional space to your home, but it could also increase what it’s worth. According to Nationwide, a loft conversion can add 20% to your house value.

Compared to home extensions, loft conversions take less time, are generally cheaper, and won’t reduce the size of your garden. Construction work won’t disrupt your day-to-day living as much either. You could use that extra space as an extra bedroom (or two), a bedroom with an en-suite bathroom, or a home office.

That said, a loft conversion can be a big undertaking. You need to do extensive planning and research and create a clear budget. You might also need to think about changes to your insurance policies as a result.

Here’s everything you need to consider before committing to a loft conversion.

Loft Conversion: A Step-by-Step Guide on How to Convert a Loft
Loft Conversion: A Step-by-Step Guide on How to Convert a Loft

Converting a Loft: Each Step Explained

Is a Loft Conversion Right for Your Home?

To determine whether your house is suitable for a loft conversion, ask yourself the following questions.

Can Your Loft Actually Be Converted?

This will depend on the kind of roof you have. A traditional or ‘cut’ roof is much easier to convert than a trussed rafter roof, which will require help from a structural engineer and inserting steel beams between load-bearing walls.

You also need to consider whether your house can handle the extra weight of a loft conversion. This means checking both foundations and any beams or lintels that will carry the load. Your house may need underpinning if not, which is an added expense.

Is There Enough Space for a Loft Conversion?

Does your loft offer enough headroom? Ideally, you want at least 2.2 metres between floor and ceiling, or 2.4 metres for a trussed roof.

Are there any chimneys that pass through the space that will need removing? And where will you put any water tanks that might need to be relocated?

You’ll also need to consider if there’s room in your house for an additional staircase. It’s best to continue the stairs from an existing stairwell to create continuity and save space. But is there enough room for a standard staircase or will you need to get one custom-built?

This could be an added expense and you’ll have to check it complies with health and safety regulations.

How Will You Make Your Loft Conversion Fire Safe?

If you’re converting a loft into a bungalow, you’ll need to make sure at least one window allows for easy escape. This means a clear opening of at least 45 cm x 45 cm. The windows should also have escape hinges that allow the window to fully open so people can get out.

If your house is three storeys (including the new loft conversion), the loft will need extra fire protection. Escaping from a window is no longer an option so you’ll also need to ensure there is stair access.

To protect the stairs from fire, you must ensure all doors that open onto the stairs are 30-minute fire doors and the stairs should also lead to a hall with direct access to the outdoors.

If your stairs lead to a bedroom or other room, you may need to create a partition or, in the case of totally open-plan spaces, install a sprinkler system.

Obviously, you will also require smoke alarms in all the necessary places, or, in the case of three-storey houses, a mains-operated smoke detection system.

Will You Need Planning Permission?

The majority of loft conversions don’t require planning permission as they fall within your Permitted Development Rights. This saves you the time and cost of applying for permission from your local council.

However, Permitted Development Rights have strict parameters. For example:

  • Neither you nor previous owners should have already used the rights for an additional storey.
  • You can only extend your roof by 50m³—or 40m³ for a terrace house.
  • Your conversion shouldn’t exceed the height of the existing roof.
  • Verandas and balconies aren’t permitted, although Juliet balconies are allowed.
  • Side-facing windows must be obscure-glazed.
  • Your home can’t be in conservation or other designated areas.

For a quick indication of whether it’s easy to get permission for your conversion, look at your street. Are there any other homes with loft conversions?

Will it Actually Increase the Value of Your Home?

If you’re going to invest a substantial amount of money into your loft conversion, you want to be sure that it will add to the value of your home. The best way to do this is to check with a local estate agent.

Start Designing

The first step in designing and creating a brief for your loft conversion is to decide what kind of conversion you want. These are your options:

Internal Loft Conversion

Also known as a roof light conversion, this is the cheapest and most straightforward kind of loft conversion. You just add windows, insulation, and floor reinforcements. An internal loft conversion usually doesn’t require planning permission and typically costs around £15,000, or between £1,200 and £1,500 per square metre.

Dormer Loft Conversion

These kinds of loft conversions are also fairly simple. They involve adding dormer windows to increase headroom and are a good option for homes with less spacious attics. Dormer windows are typically added to the back of the property, but they can also be added to the front or side, although this may require planning permission.

You’re looking at between £20,000 and £45,000 for a dormer loft conversion. Sometimes dormers are made off-site by conversion companies and then lifted into place for faster installation and weatherproofing.

Hip-to-Gable Conversion

These are a good choice for bungalows or semi-detached properties. Essentially, you create more space by turning a hipped roof with three sloped sides into a gable end, removing the sloping roof to maximise headroom inside the loft. This kind of loft conversion costs around £30,000.

Mansard Conversion

Named after French architect François Mansard, a mansard roof is the kind of loft you typically see in cities like Paris. Essentially, it’s when a sloping roof is replaced with a new structure that is almost totally upright with an almost completely flat roof.

Prefabricated Roof

This means replacing the entire existing roof structure with a bigger one, usually built off-site and installed by a crane. It could entail living without a roof for quite a long time, and, like mansard and hip-to-gable conversions, is complex and expensive. It could set you back at least £40,000.

Get Plans Drawn Up

Once you’ve decided what you want your loft conversion to look like, you can get an architect or designer to draw up detailed plans. It’s definitely worth getting your designer to show how much headroom you’ll have in the drawings so you can visualise what it will look like and won’t be disappointed with the result.

Another option is to hire a design and build company, who will be in charge of both the design process and the build process with an all-inclusive package.

Your plans may also require input from a structural engineer, which could cost between £600 and £2,000. Meanwhile, planning applications cost around £172. Even if you don’t need planning permission, we recommend that you get a certificate for lawful development. This costs around £86 and is very useful when it comes to selling the house.

Get Approval for Your Plans

Building Regulations require that all homes be checked by a building control surveyor who will issue a certificate upon final inspection. They need to know your conversion meets various targets and requirements, including standards for thermal efficiency, safety, acoustic insulation, and ventilation. They might even check for bats living in your loft.

An approved design will allow builders to give you a more concrete quote rather than a vague estimate.

According to the Party Wall Act 1996, you must also tell your neighbours if you carry out any building work near or on a shared property boundary or a ‘party wall.’ You should give them between 2 months and a year’s notice.

Source Quotes from Builders

Choosing a builder should be done carefully. Get recommendations from your neighbours or friends and family. You want a shortlist of between three and five different builders with detailed quotes that include all possible fees that might be incurred.

Verify any references, testimonials, credentials, and insurance information, before making an informed decision.

Finally, consider when you want your loft conversion to take place. Summer is the best season for construction work, weather-wise. Remember that your chosen builder probably won’t be available to start immediately.

Tell Your Insurer

As these changes might affect your home’s structure, security, and value, you need to tell your insurance company. Specialist renovations insurance is also a good idea for extensive building work as it covers things going wrong during construction.

Begin Work on Your Loft Conversion

Next up, work begins converting your loft into a livable space. This involves multiple different stages, including:

  • Removing any internal support struts. These will then need to be replaced with new ones.
  • Fitting new floor joists to form a floor structure. Because the ceiling can’t serve as a floor structure, builders will need to fit new supports, raised slightly in order to stop the floor from coming into contact with the ceiling plasterboard below. In small loft conversions, this floor support may also support the sloping rafters by means of a timber stud wall.
  • Fitting the staircase. Any custom designs will need to be approved by your building control officer first. You may also need to fit a partition wall if necessary.
  • Fitting windows. This usually means skylights or dormer windows.
  • Installing insulation. If you choose to replace your roof tiles at the same time, you can place insulation between the rafter and the new covering. Otherwise, you’ll need to fit the insulation between the rafters and under the rafters. A high-performance insulation board is the best option. For roofs with breathable felt, you’ll need to leave a gap above the insulation to make sure there’s enough ventilation to prevent condensation.
  • A mineral fibre quilt between the joists can reduce sound transmission. You may also want to insulate between the bathroom and bedroom or the party wall if you have neighbours.

Additional Considerations for Your Loft Conversion

In addition to the work mentioned above, you’ll also need to think about:

  • Ventilation – bathrooms will require extractor fans to boost ventilation. You may also need to consider other background ventilation in your loft, such as air bricks or trickle vents.
  • Heating – most of the time, this simply requires extending the existing central heating system. However, multiple additional radiators may mean upgrading your boiler. Underfloor heating is another option too.
  • Plumbing – if your loft conversion includes an en-suite, it’s easiest to extend the existing plumbing system. When designing your space, try to position the bathroom to make this feasible.
  • Electrics – you can probably extend your existing circuit, but you may need a new one. Any electricians should give you a BS7671 test certificate after installation.

Get a Completion Certificate

After a building control surveyor has inspected the building, both during and after the work has been finished, they’ll issue a completion certification that shows it complies with the necessary building regulations. Buyers may ask to see this certificate when it comes to selling your property.

Loft Conversions: The Long and Short of it

A loft conversion can be a real asset to your property, providing valuable extra space with less expense and hassle than an extension.

However, for a loft conversion to be worth the money, it needs to be carefully designed with all the necessary precautions. We recommend hiring a professional to carry out your loft conversion and always doing your homework before committing to a contractor.

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