If your house feels too small but you don’t want to move, your loft might be the answer. Understanding the types of loft conversion available helps you pick the right one for your roof, your budget, and your plans.
At ABL Design & Build, we help homeowners choose the best types of loft conversion for their property. This guide walks you through every option, the costs, and what suits your home best.
What Is a Loft Conversion?
A loft conversion turns unused roof space into a usable room. It can become a bedroom, home office, nursery, or bathroom. Unlike moving house, it adds living space without the stress of relocating.
Most homes have a loft that sits empty, holding boxes and old furniture. With the right build, that same space can add a full extra room and real value to your home.
Different Types of Loft Conversion Explained
There are five main different types of loft conversion used across the UK. Each one suits a different roof shape, budget, and property style. Picking the wrong one can mean wasted money or a rejected planning application.
Here are the main loft conversion types homeowners choose from:
1. Dormer Loft Conversion
The Dormer Loft Conversion is the most common choice. It is a box-shaped structure built out from the existing roof, with a flat roof and straight walls.
This type works well because it creates strong headroom across the whole loft, not just in the middle. It also allows for standard windows, which brings in good natural light.
Why homeowners pick it:
- Adds the most usable floor space for the price
- Suits terraced houses, semi-detached, and detached homes
- Often falls under permitted development, so it may not need full planning approval
- Quick to build compared to other options
Where it falls short:
- A large rear dormer can look bulky on smaller roofs
- Side dormers on terraced homes may need party wall agreements
A variation called the L-Shaped Loft Conversion combines two dormers, often built over a rear closet wing. This works well on Victorian and Edwardian houses with an existing back addition. It is one of the best ways to add a full extra bedroom with an en-suite, since it roughly doubles the loft’s footprint.
2. Hip-to-Gable Loft Conversion
A Hip-to-Gable Loft Conversion changes a sloping hipped roof end into a vertical wall. This is common on semi-detached, end-of-terrace, and detached houses where one side of the roof slopes inward instead of running straight up.
By building out the sloped side, you gain extra width and headroom right where the loft was previously cut short. This is often paired with a rear dormer for a bigger combined space.
Why homeowners pick it:
- Adds significant headroom along one whole side of the loft
- Blends naturally with the existing house shape
- Works well for bungalows, where roof height is often limited
Where it falls short:
- Not suitable for mid-terrace homes, since there’s no hipped end to alter
- Usually requires planning permission rather than falling under permitted development
- Can look uneven if neighbouring houses haven’t done the same conversion
If you own a semi-detached house with a hipped roof and want maximum space, a hip to gable conversion combined with a dormer is often the strongest option.
3. Mansard Loft Conversion
The Mansard Loft Conversion is built by raising the party wall and replacing the roof slope with a steep, almost vertical wall set back slightly from the front. Mansard roofs are a traditional London style, seen on countless terraced streets.
This conversion gives the most headroom and floor space of any loft conversion type, since it reshapes nearly the whole roof structure.
Why homeowners pick it:
- Maximum extra space and headroom
- Suits period and terraced homes especially well
- Often increases resale value more than other options, since it can add a full storey
Where it falls short:
- Almost always requires planning permission
- Some councils, including parts of London, are strict about approving this type of conversion
- Higher cost and longer build time than a dormer
For owners of Victorian or Edwardian terraced houses, especially in conservation areas, a mansard is often the only realistic way to gain a full-height room. It’s worth checking with your local council early, since rules vary street by street.
4. Velux (Rooflight) Loft Conversion
A Velux (Rooflight) Loft Conversion keeps your existing roof shape exactly as it is. Instead of building outward, you fit windows into the roof slope and strengthen the floor below.
This is the simplest and cheapest type of conversion on this list, and it’s often the fastest to complete.
Why homeowners pick it:
- The lowest-cost option among all loft extension types
- More likely to get approved in conservation areas, since the roofline doesn’t change
- Brings in plenty of natural light through angled rooflights
Where it falls short:
- Headroom is limited to where the roof is already tall enough
- Doesn’t add new floor space, so it suits storage rooms or small offices better than full bedrooms
- May still need planning permission if windows face the front of the house
If your loft already has decent height in the middle and you’re working to a tight budget, this is usually the quickest route to a usable room.
5. Gable Loft Conversion
A Gable Loft Conversion extends the existing gable end wall upward and outward, often paired with other structural changes. It’s closely related to the hip-to-gable style but applies where a gable wall already exists and needs extending rather than created from a hip.
This is common on detached and semi-detached houses with a gable-fronted design.
Why homeowners pick it:
- Keeps the roofline visually consistent with the rest of the house
- Adds strong headroom along the gable wall
- Works well combined with a rear dormer for an L-shaped layout
Where it falls short:
- Structural work along a load-bearing gable wall can add cost
- Less common, so fewer builders specialise in it locally
Related: How Long Does a Loft Conversion Take?
How Roof Shape Affects Which Loft Conversion You Need
Your roof shape often decides which types of loft conversions are realistic before budget even comes into play.
- Hipped roof: Best suited to hip-to-gable or a combined hip-to-gable and dormer build
- Gable-end roof: Works well with a dormer, gable extension, or L-shaped layout
- Existing mansard or flat roof: Often easiest to extend with a small dormer addition
- Terraced house with limited width: Mansard or rear dormer tends to work best
A structural engineer or architect can confirm what your existing roof allows before you commit to a design.
Planning Permission and Building Regulations
Many loft conversions fall under permitted development rights, meaning you may skip full planning approval. However, several loft conversion types still need a formal application.
A project usually requires planning permission when:
- You live in a conservation area or a listed building
- The roof extension exceeds permitted development volume limits
- You’re altering a roof in a way that’s visible from the street
- Your council has removed permitted development rights in your area (an Article 4 direction)
Even permitted development projects must meet Building Regulations covering fire safety, insulation, structural strength, and staircase access. Always confirm requirements with your local planning authority or a qualified building control body before starting work, since rules differ between councils.
Loft Conversion Cost Comparison
Costs vary by type of conversion, location, and finish level. As a general guide across the UK:
- Velux (Rooflight): typically the lowest cost, since no structural roof changes are needed
- Dormer: moderate cost, with strong value for the space gained
- Hip-to-gable: higher than a dormer due to extra structural work
- Mansard: usually the highest cost, reflecting the scale of rebuilding involved
Prices shift depending on whether you’re adding an en-suite, moving plumbing, or upgrading insulation. Getting two or three quotes from established local builders gives you a realistic budget range for your specific property.
Which Loft Conversion Suits Different Property Types?
Not every conversion fits every house. Matching the build to your property types avoids wasted design fees.
- Terraced houses: Mansard or rear dormer conversions tend to work best
- Semi-detached houses: Hip-to-gable, often combined with a dormer
- Detached houses: Most loft extension types are possible, including full mansard builds
- Bungalows: Hip-to-gable is common, since it adds vertical wall height where it’s needed most
- Period and listed properties: Mansard or Velux conversions, depending on conservation rules
Best Loft Conversion for Specific Needs
Different goals call for different builds.
- Extra bedroom for a growing family: Dormer or L-shaped conversion, for maximum floor space
- Home office: Velux conversion if your loft already has height, or a small dormer for more room
- Nursery: Dormer conversion, since it adds steady headroom and natural light
- Adding rental value or an HMO room: Mansard or dormer, depending on what local rental demand expects
- Increasing resale value: Mansard conversions often add the most value in period properties, while dormers offer the best return for most other house styles
Common Mistakes to Avoid
- Choosing a type of conversion based on cost alone, without checking what your roof shape allows
- Skipping a planning permission check in a conservation area
- Underestimating headroom requirements, especially with Velux-only builds
- Not budgeting for staircase repositioning, which is often needed regardless of conversion type
- Hiring a builder without loft-specific experience or proper structural sign-off
Why Work With ABL Design & Build
Choosing between types of loft conversions is easier with an experienced team guiding the decision. ABL Design & Build has handled dormer, hip-to-gable, mansard, and Velux projects across loft conversions London homeowners trust us with every year.
We assess your existing roof, check planning rules for your area, and recommend the loft conversion types that fit your budget and goals. Every project includes structural advice, Building Regulations compliance, and a clear cost breakdown before work begins.
Conclusion
There are several types of loft conversion to choose from, and the right one depends on your roof shape, budget, and property type. Dormer, hip-to-gable, mansard, Velux, and gable conversions each offer different space, light, and cost outcomes. Getting expert advice early avoids wasted time on designs that won’t get approved. Contact us today for a free consultation and find out which loft conversion fits your home best.
Frequently Asked Questions
Which type of loft conversion is best?
The best option depends on your property’s roof structure, budget, and goals. A Dormer Loft Conversion is often the most popular choice because it creates extra floor space, improves headroom, and suits many UK homes. If you want maximum space, a Mansard Loft Conversion may be the better option.
What are the main types of loft conversion?
The main types of loft conversion include Dormer Loft Conversion, Hip-to-Gable Loft Conversion, Mansard Loft Conversion, Velux (Rooflight) Loft Conversion, and L-Shaped Loft Conversion. Each design offers different levels of space, cost, and structural changes.
Which loft conversion adds the most value to a property?
A Mansard Loft Conversion often adds the most value because it creates the largest amount of additional living space. However, a Dormer Loft Conversion usually provides the best balance between cost and return on investment.
Do all loft conversions require planning permission?
No. Many loft conversions fall under permitted development rights. However, a project may require planning permission if the property is in conservation areas, is a listed building, or involves major changes to the roof structure.
What is the cheapest type of loft conversion?
A Velux (Rooflight) Loft Conversion is generally the most affordable option. It works within the existing roof structure and requires fewer structural alterations than other loft conversion types.
What is the most expensive loft conversion?
A Mansard Loft Conversion is usually the most expensive because it involves significant structural changes to the roof. The higher cost is often justified by the amount of extra space created.