Loft conversion: what you need to know before getting started
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Thinking of converting your loft? It’s one of the most popular ways to add extra space and value to your home. For many homeowners, a loft conversion is a smarter option than moving house or building a full extension.
Before you start dreaming of skylights and spare bedrooms, there are a few important checks to make. Not every loft is suitable, and there are rules you need to follow – even if planning permission isn’t required.
This guide covers everything you need to know before getting started.
Is your loft suitable for conversion?
Minimum head height
The first thing to check is how much headroom you’ve got. In most cases, you need at least 2.2 metres at the highest point of your loft. That’s measured from the existing floor to the highest point of the ceiling.
If you have this much space (or more), you’re off to a good start.
Roof pitch and usable space
The slope of your roof affects how much space you’ll actually be able to stand and move around in. You don’t need to know the exact pitch – just climb up and see how the space feels.
Ask yourself:
- Can you stand upright without crouching or leaning?
- How many steps can you take before you need to duck?
- Will there be enough room for furniture and storage?
Roof structure and support
Homes built before the 1960s usually have traditional timber-framed roofs (called rafters), which are easier to convert.
Homes built after the 1960s often use roof trusses – those W-shaped frames that take up more space and require extra structural work.
If your loft has trusses, it can still be converted, but parts of the structure may need to be removed and replaced with steel beams or reinforced joists. This adds to the cost and complexity.
If you’re unsure, a builder or structural engineer can take a look and give you clear advice.
Check your neighbourhood
Not sure if your loft can be converted? Take a walk around your area. If you spot houses similar to yours with skylights or dormers, there’s a good chance your property is suitable too.
The main types of loft conversion
There are several types of loft conversion, depending on your property and budget.
Roof light conversion
This is the simplest and most affordable option. No changes are made to the roof structure – you just add skylights, insulation and flooring. Great if your loft already has enough height.
Dormer conversion
A dormer is a box-like extension that sticks out from your existing roof. It adds more headroom and floor space and is one of the most popular conversion types in the UK.
There are a few variations (e.g. rear dormer, L-shaped dormer) depending on your roof and home shape.
Mansard conversion
This is a much bigger project that essentially adds another full storey to your house. It involves replacing one or both roof slopes with a new angled wall at 72 degrees. Mansards are usually built at the rear and are common in city terraces.
Hip to gable conversion
Perfect for semi-detached or detached homes with a sloping side roof (hipped roof). The slope is removed and replaced with a vertical wall (gable end), creating more internal space.
How much does a loft conversion cost?
Loft conversions aren’t cheap, but they can add significant value to a home. Most UK projects cost between £30,000 and £60,000 depending on the type.
For a detailed breakdown, see our full guide: How much does a loft conversion cost in the UK?
Do you need planning permission?
In most cases, you don’t need planning permission to convert your loft. This is because loft conversions usually fall under Permitted Development Rights – rules that allow homeowners to make certain changes without full planning approval.
But there are limits and conditions:
- Materials must be similar to your existing home
- You can’t raise the roof height
- You can’t add balconies or large platforms
- Any rear extensions (like dormers) must not overhang the outer walls
- Side windows must be obscure-glazed and non-opening below 1.7m
There are also volume limits:
- Terraced homes: max 40m³ of additional space
- Semi-detached and detached homes: max 50m³
These limits apply to all roof enlargements, including any previous ones.
Watch out for restricted areas
Some locations in the UK have stricter planning rules. Even if you qualify for permitted development elsewhere, you may need full planning permission in these designated areas. These include:
- Conservation areas
There are over 10,000 designated conservation areas in England. You can check your local authority’s website or use Historic England’s map to find out if your home is in one. - National Parks
Planning is more tightly controlled in protected landscapes like the Lake District, Peak District, Cairngorms or Snowdonia. - Areas of Outstanding Natural Beauty (AONB)
Similar to National Parks but typically smaller, AONBs also come with restrictions. You can find more about them on the National Association for AONBs site. - World Heritage Sites
These sites are recognised for their international cultural or natural significance. See the full list for the UK at the UNESCO World Heritage Centre. - The Norfolk or Suffolk Broads
These areas have their own planning authority. You can find more information on the Broads Authority website.
If your home is located in one of these areas, it’s best to speak directly with your local planning department before starting any work.
You’ll still need building regulations approval
Even if you don’t need planning permission, you will need to comply with building regulations. These rules cover:
- Structural safety (including beams and load-bearing walls)
- Fire safety (escape routes, smoke alarms)
- Insulation and ventilation
- Staircases and access
- Electrical and plumbing work (if needed)
Speak to your local authority or a professional builder to make sure you understand the requirements. You’ll usually need to submit detailed plans and get inspections during the build.
What to do next
A loft conversion is a big project, but breaking it down into clear steps makes the process far less daunting.
- Check if your loft is structurally suitable
- Confirm whether planning permission is needed
- Speak to your local planning department if you’re in a restricted area
- Get quotes from at least three builders (
- Ask what’s included in each quote (design, drawings, approvals, structural work, finishing)
- Plan how you’ll use the space and set a realistic budget
Final thoughts
A loft conversion can be one of the most effective ways to add space and value to your home, but it isn’t a decision to rush.
From checking head height and roof structure to understanding planning rules and building regulations, there are a few essential steps before you dive in. Once you’ve done those checks, you can start exploring design options, costs, and builders with confidence.
Treated as a well-planned project, a loft conversion can transform your home and give you the extra space you’ve been looking for.
Need inspiration? See our top attic conversion ideas for bedrooms, offices, playrooms and more.
