Loft conversion drawings

Loft conversion drawings — planning & building regulations.

With rising house prices and space at a premium, more homeowners are converting their underused attic into valuable living areas — a bedroom, a home office, or an en-suite master suite. A loft conversion is one of the most cost-effective ways to add space and value to your home.

Types of loft conversion

Common layouts we draw

Rooflight (Velux) loft conversion

Best for: High-pitched roofs with plenty of existing space

Pros

Minimal structural alteration
Lower cost and faster construction
Often within Permitted Development

Cons

Limited headroom
May not suit all roof types or room uses

Dormer loft conversion

Best for: Terraced and semi-detached houses

Pros

Increases usable floor space and natural light
Popular and versatile
Often falls under Permitted Development

Cons

Boxy appearance unless well designed
May not suit front-facing elevations in conservation areas

Hip-to-gable loft conversion

Best for: End-of-terrace or detached homes with hipped roofs

Pros

Substantial increase in headroom and floor space
Better suited for creating larger rooms

Cons

Requires major structural alteration
Almost always requires planning permission in conservation areas

Mansard loft conversion

Best for: Homes in cities, terraces or properties with planning flexibility

Pros

Maximum internal space and ceiling height
Can be aesthetically pleasing on period homes

Cons

Most expensive and time-consuming
Requires full planning permission
Major structural work required

L-shaped dormer conversion

Best for: Houses with rear projections (outriggers)

Pros

Can create multiple rooms or self-contained units
Excellent use of space on extended properties

Cons

Design complexity
May require planning permission depending on roof size

Is my loft suitable?

Five things to check

Head height	Ideally at least 2.2 m from ceiling joist to ridge
Roof pitch & structure	Traditional cut timber roofs convert more easily than modern trussed
Staircase placement	Must allow safe, accessible entry without compromising existing space
Chimneys and services	Can add complexity or limit design options
Structural integrity	New floors and supports may be needed to comply with Building Regs

Cost guide (2025)

What does it cost?

Rooflight / Velux	£20,000 – £35,000
Rear dormer	£35,000 – £60,000
Hip-to-gable	£45,000 – £70,000+
Mansard	£55,000 – £85,000+
L-shaped dormer	£50,000 – £80,000+

Costs depend on roof complexity, internal finish, staircase alterations and professional/legal fees.

Building Regulations for loft conversions

What your drawings must show

Structural safety (floors, beams, supports)
Fire safety (fire-resistant doors, escape routes, alarms)
Insulation and ventilation
Staircase design (steepness, head clearance)
Soundproofing
Windows and natural light (minimum 1/20th of floor area)

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