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Crest Projects – Extension Cost Planner

How Much Does an Extension Cost?

Use our Crest Projects extension planner to see real examples that match your property. Select your house type and exterior layout, then browse similar Crest case studies with guide costs.

  • Built around real Crest Projects case studies
  • Ideal for early planning and ideas
  • Full, fixed quotation available after a site visit
All costs shown in the example projects below are estimates only and exclude VAT. Final pricing will depend on specification, access, structural design and planning considerations.
Crest Extension Planner
Step 01 of 02
Step01
House typeSelect from below

Choose the house that best matches your property. We’ll use this to filter real-world Crest projects below.

Exterior typeSelect from below

Rear, side and wraparound layouts all create different types of space. We’ll now show Crest projects that match your selection.

Selected: Choose your house type

Matching Crest Projects Extension Costs

These case studies match your chosen house type and exterior layout. Use them as a guide for scope, layout and budget.

Detached rear flat
Detached · Rear · Flat roof
from £160kGuide | 26–30m²
Kitchen / diner
Detached gable
Detached · Rear · Gable roof
from £170kGuide | 28–32m²
Feature gable with vaulted ceiling and roof glazing.
Detached wrap
Detached · Wraparound · Flat roof
from £190kGuide | 35–40m²
Full-width family space with utility and WC.
Semi rear
Semi-detached · Rear · Flat roof
from £145kGuide | 22–26m²
Classic London semi extended for open-plan living.
Semi crown
Semi-detached · Rear · Crown roof
from £153kGuide | 24–28m²
Crown roof with perimeter falls for hidden drainage.
Semi wrap medium
Semi-detached · Wraparound · Flat roof
from £180kGuide | 32–36m²
Side-return and rear extension with large rooflights.
End rear flat
End terrace · Rear · Flat roof
from £140kGuide | 20–24m²
Bright extension with garden-facing glazing.
End gable
End terrace · Rear · Gable roof
from £150kGuide | 22–26m²
Gable form to match neighbouring rooflines.
End wrap large
End terrace · Wraparound · Flat roof
from £175kGuide | 30–34m²
Side-return plus rear to create L-shaped family space.
Flat back pitched
Terraced flat-back · Rear · Flat roof
from £130kGuide | 18–22m²
Efficient rear extension for Victorian flat-back layout.
Flat back crown
Terraced flat-back · Rear · Crown roof
from £137kGuide | 20–24m²
Crown roof to maintain neighbour light angles.
Side return small flat
Terraced flat-back · Side infill · Flat roof
from £135kGuide | 20–24m²
Infill side-return creating full-width rear space.
Wrap large gable
Terraced flat-back · Wraparound
from £165kGuide | 28–32m²
Wraparound with lantern roof and large sliders.
Detached package
Detached · Rear + Loft · Flat roofs
from £230kGuide | package
Extension with dormer loft bedroom & ensuite.
Semi wrap loft
Semi-detached · Wrap + Loft
from £220kGuide | package
Wraparound extension with rear dormer loft conversion.
End rear loft
End terrace · Rear + Loft
from £205kGuide | package
Rear extension and mansard-style loft bedroom.
Compact rear
Semi-detached · Compact rear · Flat roof
from £115kGuide | 14–18m²
Smaller extension focused on dining area and glazing.
Compact crown
Terraced flat-back · Compact rear · Crown
from £123kGuide | 16–20m²
Crown / pitched solution used where height restrictions apply.
Side infill
Terraced flat-back · Side infill only
from £110kGuide | 12–16m²
Infill between outrigger and boundary with rooflights.
Pitched gable feature
Detached · Rear · Pitched / gable feature
from £160kGuide | 24–28m²
Glazed gable facing garden for maximum drama.
Large wrap hipped
Detached · Large wrap · Hipped
from £200kGuide | 38–42m²
Oversized family space with walk-in pantry and utility.
Wrap medium hipped
Semi-detached · Wraparound (hipped)
from £210kGuide | 38–42m²
Crown / hipped solution to control overall ridge height.
Corner plot
End terrace · Corner plot · Rear extension
from £170kGuide | 28–32m²
Tailored solution for corner site with dual-aspect glazing.
Rear kitchen snug
End terrace · Rear · Kitchen / snug layout
from £155kGuide | 24–28m²
Zoned seating nook with rooflights over dining area.
Premium wrap
Detached · Premium spec · Wrap
from £230kGuide | 36–40m²
High-end finishes, bespoke joinery and integrated lighting.
© Crest Projects Ltd · All guide costs subject to survey and detailed design.
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