Loft: L-shaped dormer

Maximise your attic with an L-shaped (or “dog leg”) dormer. Perfect for certain types of properties, this loft conversion gives you two sections at right angles, joining at the corner. With all this extra space, you can finally have that guest room, master bedroom, en-suite and walk-in wardrobe you’ve always dreamed of.

What house styles can have an L-shaped loft conversion?

Terraced and semi-detached properties from the Victorian period are most suitable for this project, when they have:

Main roof: larger section placed here, positioned higher up, facing rear
Back extension: for smaller part, lower height, facing neighbour

Wondering what to use each area for? You can usually fit in:

Two bedrooms: larger
One bathroom: smaller
Juliet balcony: rear-facing, for ventilation/light

It makes sense to place the washing facilities at the back, as that’s where you’ll find the soil pipe, so plumbing is much more straightforward.

There are other options, such as:

Study/office
Fitness/yoga studio
Bedroom with dressing room
Playroom/nursery

L-shaped dormer loft conversion planning permission

Keep to certain guidelines and you won’t need planning permission for your expansion, as it’ll come under Permitted Development. These currently include:

No more than 50m³ added (detached/semi), 40m³ (terraces)
Not in conservation district
Not a listed building
No balcony (Juliet allowed)
No materials that aren’t in keeping with original structure

The part facing neighbours might require permission. The company carrying out the work should take into consideration all of these factors.

There are also Building Regulations that your construction firm needs to adhere to. Areas that need to be approved/certified include:

Headroom (2m height usually required)
Roof
Heating
Plumbing
Electricals
Stability of structure
Insulation
Sound proofing
Glass/windows/balconies and flashings
Stairs
Fire safety

L-shaped dormer loft conversion cost

From £50,000

It’s one of the most expensive ways to extend your home, but don’t let that put you off. An L-shaped dormer loft conversion price is high because it adds so much floorspace with usable headroom alongside — almost as much as your existing first floor.

The cost is about £15K more than a standard one, but given that you get another part for an additional room, it’s an investment well worth making. It’ll enlarge your liveable areas significantly, and increase the value of your property should you sell in the future.

Timeframes are longer, naturally, with an average of 7-10 weeks. So it’s understandable that the cost is higher in line with extended labour plus extra materials.