At a glance

What to expect from this build.

Typical build time10–20 weeks
PricingFree cost estimate
Loft conversion types

Which loft conversion is right for your home?

Rear dormer

A full-width box dormer on the rear roof slope: the most common way to add a bedroom and bathroom, and often possible without a full planning application.

Hip-to-gable

For semi-detached and end-of-terrace homes with a sloping side roof: the hip is rebuilt as a vertical gable, usually with a rear dormer, to create far more head height.

Mansard

The rear roof is rebuilt almost vertically with a shallow top, giving the most usable space. Popular on London terraces and usually needs full planning permission.

L-shaped dormer

A main rear dormer plus a second dormer over the back addition (outrigger), common on Victorian and Edwardian terraces, giving room for two bedrooms or a large suite.

See what your loft conversion would cost
How it works

From first visit to handover

  1. Free consultation and site surveyWe visit, check your loft's head height and roof structure, and agree a budget range.
  2. Design and drawingsA measured survey and architectural drawings, refined with you until the layout and staircase position are right.
  3. PlanningWe confirm whether your loft can go ahead under permitted development (with a lawful development certificate) or needs planning permission, and manage the application.
  4. Structure, building regulations and party wallStructural calculations for the new floor and steel beams, a fire-safe escape route, building control and any party wall notices arranged before work starts.
  5. BuildVetted trades managed by a single project lead, with regular updates.
  6. HandoverBuilding control sign-off, snagging and a walk-through of your new rooms.
Finished loft conversion bedroom with roof windows

Loft conversions · London & selected Kent and Essex towns

Loft conversions, designed around you.

Space to sleep, work or unwind. Discover what your loft could become.

Discuss your loft See loft projects
  • Specialist loft teams
  • Building surveyor oversight
  • Clear guidance throughout

Plan your loft budget.

Guide construction prices + VAT
Single dormer£48k–£55k
L-shape mansard£75k–£85k
L-shape loft£58k–£65k
Hip-to-gable L-shape£72k–£85k
Hip-to-gable£57k–£65k
Double mansard£92k–£110k

Typical construction: 10–20 weeks

Included: works to a plaster finish, plus basic second-fix electrics, plumbing and carpentry.

Not included: painting, flooring, tiling, glazing, sanitaryware supply and bespoke carpentry.

Guide budgets only. Final price and programme depend on survey, drawings and specification.

Get my loft estimate

See what a loft could become.

Loft conversion bedroom with feature wallpaper and roof windows

Room to sleep

Loft room with a desk under a roof window and fitted wardrobes

Room to work

Bright loft room with a sofa and roof windows

Space to unwind

View loft projects

Which loft suits your home?

IllustrationIllustration of a house with a rear dormer loft conversion

Rear dormer

More usable room across the back.

IllustrationIllustration of a house with a hip-to-gable loft conversion

Hip-to-gable

Adds space at a sloping roof end.

IllustrationIllustration of a house with an L-shaped dormer loft conversion

L-shaped dormer

Extends over the rear addition.

IllustrationIllustration of a house with a rear mansard loft conversion

Mansard

Reshapes the roof for more usable space.

The right option depends on your property and planning requirements. Compare all four loft types in our guide →

Make the most of every metre.

Headroom, daylight, layout and storage considered together.

Cutaway illustration of a converted loft bedroom with a roof window
Natural light
Usable headroom
Room for a bedroom
Clever storage

From first visit to handover.

  1. 01

    Visit & feasibility

    Your space, ideas and budget.

  2. 02

    Design & drawings

    Layouts shaped around you.

  3. 03

    Planning

    The right application route.

  4. 04

    Technical preparation

    Structure, regulations and party wall matters.

  5. 05

    Build & regular checks

    Specialist teams. Building surveyor oversight.

  6. 06

    Finish & handover

    Final checks, snagging and documents.

Client guidesDesign meetingsRegular progress reportsSee how we manage your build

Your loft questions, answered.

Is my loft suitable for a conversion?

As a rough guide, there needs to be around 2.2 m of height from the top of the ceiling joists to the underside of the ridge. Roof shape, the space for a new staircase and the direction your roof slopes also matter. We check all of this at the free site survey.

How much does a loft conversion cost?

It depends on the type of conversion, the size of your roof and the finish you choose. Use our free cost estimator to get a budget range for your home. Every project is then priced on survey and approved drawings.

How long does a loft conversion take?

Most of our loft conversions take 10–20 weeks on site. A rear dormer is usually the quickest; mansard and hip-to-gable conversions take longer. Before that come drawings and approvals: councils aim to decide householder planning applications within 8 weeks.

Do I need planning permission for a loft conversion?

Many loft conversions on houses can be built under permitted development rights, without a full planning application, as long as:

  • the extra roof space is no more than 40 m³ on a terraced house, or 50 m³ on a semi-detached or detached house;
  • nothing is higher than the highest part of the existing roof;
  • nothing extends beyond the roof slope at the front of the house facing the road;
  • materials look similar to the existing house, and there are no balconies or raised platforms;
  • side-facing windows are obscure-glazed and don’t open below 1.7 m from the floor;
  • dormers are set back at least 20 cm from the eaves where practical.

Mansards, flats and maisonettes, homes in conservation areas, listed buildings and areas with an Article 4 direction normally need full planning permission. Building regulations approval is needed either way. We check your property’s planning history and local rules first, and recommend a lawful development certificate so you have proof the work was allowed when you come to sell.

What about party wall matters?

On terraced and semi-detached homes, usually a party wall agreement is needed: the new floor’s steel beams are normally set into the shared (party) wall, and hip-to-gable and mansard conversions may raise it. The Party Wall etc. Act 1996 says you must give your neighbours written notice at least two months before work to a party wall.

If they agree in writing, no surveyor is needed. If they don’t respond within 14 days or don’t agree, a party wall surveyor prepares an agreement (an “award”). We flag this at design stage so it doesn’t delay your start date.

Can I stay at home during the build?

In many cases, yes. This depends on the structural work, access requirements and whether essential services need to be disconnected. Before construction starts, we provide a clear schedule and explain when alternative accommodation may be useful.

Can the agreed price change?

Your price is based on the approved drawings, specification and known site conditions. Any optional additions or client-requested changes are documented and approved before they affect the project budget.

Let’s explore your loft’s potential.

Tell us what you'd like to change.

Book a free consultation
Recent projects

Recent loft conversions by Buildspace Projects

Side-return extensionBest for terraces

Side-Return

Reclaim the narrow alley beside Victorian terraces for a wide, open-plan kitchen.

Rear extensionMost popular

Rear Extension

Push the kitchen and dining out into the garden with glazed doors and rooflights.

Wrap-around extensionMost space gained

Wrap-Around

Combine a side-return and rear extension to transform the whole ground floor.

Loft conversion and bathroom remodelling · Brockley, London SE4
Explore the project →
LOFT CONVERSION / RENOVATION

Arica Road

Loft conversion and bathroom remodelling · Brockley, London SE4

Loft conversion and home renovation · Peckham, London SE15
Explore the project →
LOFT CONVERSION / RENOVATION

Choumert Road

Loft conversion and home renovation · Peckham, London SE15

Your project could be next

Let's discuss your space.

Book a free consultation and tell us what you want to change about your home.

Book a free consultation→

Frequently asked

Good questions, answered.

How much does a loft conversion cost?

It depends on the type of conversion, the size of your roof and the finish you choose. Use our free cost estimator to get a budget range for your home. Every project is then priced on survey and approved drawings.

How long does a loft conversion take?

Most of our loft conversions take 10–20 weeks on site. A rear dormer is usually the quickest; mansard and hip-to-gable conversions take longer. Before that come drawings and approvals: councils aim to decide householder planning applications within 8 weeks.

Do I need planning permission for a loft conversion?

Many loft conversions on houses can be built under permitted development rights, without a full planning application, as long as:

  • the extra roof space is no more than 40 m³ on a terraced house, or 50 m³ on a semi-detached or detached house;
  • nothing is higher than the highest part of the existing roof;
  • nothing extends beyond the roof slope at the front of the house facing the road;
  • materials look similar to the existing house, and there are no balconies or raised platforms;
  • side-facing windows are obscure-glazed and don't open below 1.7 m from the floor;
  • dormers are set back at least 20 cm from the eaves where practical.

Mansards, flats and maisonettes, homes in conservation areas, listed buildings and areas with an Article 4 direction normally need full planning permission. Building regulations approval is needed either way. We check your property's planning history and local rules first, and recommend a lawful development certificate so you have proof the work was allowed when you come to sell.

Do I need a party wall agreement for a loft conversion?

On terraced and semi-detached homes, usually yes: the new floor's steel beams are normally set into the shared (party) wall, and hip-to-gable and mansard conversions may raise it. The Party Wall etc. Act 1996 says you must give your neighbours written notice at least two months before work to a party wall.

If they agree in writing, no surveyor is needed. If they don't respond within 14 days or don't agree, a party wall surveyor prepares an agreement (an "award"). We flag this at design stage so it doesn't delay your start date.

Is my loft suitable for a conversion?

As a rough guide, there needs to be around 2.2 m of height from the top of the ceiling joists to the underside of the ridge. Roof shape, the space for a new staircase and the direction your roof slopes also matter. We check all of this at the free site survey.

Can I stay in my home during the build?

In many cases, yes. This depends on the structural work, access requirements and whether essential services need to be disconnected. Before construction starts, we provide a clear schedule and explain when alternative accommodation may be useful.

Will the price change once work starts?

Your price is based on the approved drawings, specification and known site conditions. Any optional additions or client-requested changes are documented and approved before they affect the project budget.

Ready to start your project?

Book a free site survey with a Buildspace Projects lead. No obligation, no sales pitch.

Book a free survey
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