Ground floor side
West Berkshire
· Detached
· 2022
£45k
· Sep '22
Average build cost for a ground floor side extension is £90k - £110k
Build cost
£90k - £110k
The average cost of a project in the last 2 years.
Value-add
2-4%
The average value uplift of a project in the last 2 years.
Project length
8-9 months
The average time taken to complete a project in the last 2 years.
Planning approval
93%
The average approval rate of projects in the last 2 years.
Time to approval
62 days
The average number of days taken to approve a project in the last 2 years.
Number approved
29,509
The number of applications approved in the last 2 years.
Ground floor side
Southwark
· End Of Terrace
· 2025
£66k
· Dec '24
Average build cost for a ground floor side extension is £90k - £110k
Build cost
£90k - £110k
The average cost of a project in the last 2 years.
Value-add
2-4%
The average value uplift of a project in the last 2 years.
Project length
8-9 months
The average time taken to complete a project in the last 2 years.
Planning approval
93%
The average approval rate of projects in the last 2 years.
Time to approval
62 days
The average number of days taken to approve a project in the last 2 years.
Number approved
29,509
The number of applications approved in the last 2 years.
Ground floor side
Lewisham
· Semi Detached
· 2024
£91k
· Sep '23
Average build cost for a ground floor side extension is £90k - £110k
Build cost
£90k - £110k
The average cost of a project in the last 2 years.
Value-add
2-4%
The average value uplift of a project in the last 2 years.
Project length
8-9 months
The average time taken to complete a project in the last 2 years.
Planning approval
93%
The average approval rate of projects in the last 2 years.
Time to approval
62 days
The average number of days taken to approve a project in the last 2 years.
Number approved
29,509
The number of applications approved in the last 2 years.
Ground floor side
Bromley
· Semi Detached
· 2024
£76k
· Nov '23
AI images
Images are AI-generated for homeowner privacy
Average build cost for a ground floor side extension is £90k - £110k
Build cost
£90k - £110k
The average cost of a project in the last 2 years.
Value-add
2-4%
The average value uplift of a project in the last 2 years.
Project length
8-9 months
The average time taken to complete a project in the last 2 years.
Planning approval
93%
The average approval rate of projects in the last 2 years.
Time to approval
62 days
The average number of days taken to approve a project in the last 2 years.
Number approved
29,509
The number of applications approved in the last 2 years.
Ground floor side
Greenwich
· Semi Detached
· 2025
£63k
· May '24
Average build cost for a ground floor side extension is £90k - £110k
Build cost
£90k - £110k
The average cost of a project in the last 2 years.
Value-add
2-4%
The average value uplift of a project in the last 2 years.
Project length
8-9 months
The average time taken to complete a project in the last 2 years.
Planning approval
93%
The average approval rate of projects in the last 2 years.
Time to approval
62 days
The average number of days taken to approve a project in the last 2 years.
Number approved
29,509
The number of applications approved in the last 2 years.
Ground floor side
Enfield
· End Of Terrace
· 2022
£105k
· Feb '22
Average build cost for a ground floor side extension is £90k - £110k
Build cost
£90k - £110k
The average cost of a project in the last 2 years.
Value-add
2-4%
The average value uplift of a project in the last 2 years.
Project length
8-9 months
The average time taken to complete a project in the last 2 years.
Planning approval
93%
The average approval rate of projects in the last 2 years.
Time to approval
62 days
The average number of days taken to approve a project in the last 2 years.
Number approved
29,509
The number of applications approved in the last 2 years.
Ground floor side
Broxbourne
· Semi Detached
· 2022
£152k
· Nov '22
Ground floor side
Braintree
· Detached
· 2025
£185k
· Feb '25
AI images
Images are AI-generated for homeowner privacy
Ground floor side
South Cambridgeshire
· Semi Detached
· 2024
£146k
· Aug '24
Ground floor side and internal alterations
Woking
· Detached
· 2025
£109k
· Jun '25
Loft main dormer and ground floor side
Reading
· Detached
· 2022
£138k
· Oct '22
Ground floor side, internal alterations & internal alterations
Elmbridge
· Detached
· 2024
£196k
· Oct '23
AI images
Images are AI-generated for homeowner privacy
Ground floor side and internal alterations
Crawley
· Semi Detached
· 2024
£100k
· Feb '24
Ground floor side, two storey rear & facade alterations
Elmbridge
· Detached
· 2023
£213k
· Oct '22
Ground floor side and garage conversion
Reigate and Banstead
· Detached
· 2024
£362k
· Jun '24
Ground floor rear, ground floor side, internal alterations & first floor side
Richmond upon Thames
· Semi Detached
· 2024
£289k
· Aug '24
AI images
Images are AI-generated for homeowner privacy
Ground floor side and ground floor front
Harrow
· Semi Detached
· 2024
£118k
· Jul '24
Ground floor side infill, ground floor side, internal alterations & Loft L shaped dormer
Lambeth
· Semi Detached
· 2022
£219k
· Jan '23
Ground floor side and garage conversion
Southwark
· Detached
· 2023
£69k
· Sep '22
Ground floor rear, ground floor side, ground floor front & internal alterations
Bromley
· Detached
· 2023
£176k
· Jun '23
AI images
Images are AI-generated for homeowner privacy
Ground floor rear and ground floor side
Bromley
· Terrace
· 2022
£95k
· Aug '22
Ground floor side, loft hip to gable with main dormer, internal alterations, internal alterations & first floor rear
Tunbridge Wells
· Semi Detached
· 2023
£213k
· Jan '24
Ground floor side
Waverley
· Bungalow
· 2023
£76k
· Jul '22
Ground floor side
Waverley
· Detached
· 2026
£168k
· Jul '26
AI images
Images are AI-generated for homeowner privacy
Ground floor side
Mole Valley
· Semi Detached
· 2025
£64k
· Feb '25
Ground floor side
Mole Valley
· Detached
· 2026
£79k
· Dec '25
Ground floor side
Merton
· End Of Terrace
· 2023
£61k
· May '23
Ground floor side
Hammersmith and Fulham
· Terrace
· 2026
£112k
· Jul '26
AI images
Images are AI-generated for homeowner privacy
Ground floor side
Buckinghamshire
· Semi Detached
· 2023
£65k
· Apr '23
Ground floor side
Bromley
· Semi Detached
· 2026
£130k
· Nov '25
Ground floor side
Bromley
· Detached
· 2025
£152k
· Sep '25
Ground floor side
Haringey
· Detached
· 2024
£209k
· Jul '24
AI images
Images are AI-generated for homeowner privacy
Ground floor side
Bexley
· Semi Detached
· 2025
£78k
· Dec '25
Ground floor side
Bexley
· Semi Detached
· 2024
£89k
· Jun '24
Ground floor side
Wealden
· Detached
· 2023
£64k
· Nov '22
Ground floor side
Rother
· Semi Detached
· 2022
£78k
· Jun '22
AI images
Images are AI-generated for homeowner privacy
Ground floor side
South Cambridgeshire
· Detached
· 2025
£153k
· Oct '25
Ground floor side, loft no dormer & ground floor front
East Hampshire
· Semi Detached
· 2022
£79k
· Feb '26
Ground floor side, internal alterations & garden annex
Chichester
· End Of Terrace
· 2023
£267k
· Jan '23
Ground floor side and internal alterations
Waverley
· Detached
· 2025
£102k
· Mar '26
AI images
Images are AI-generated for homeowner privacy
Ground floor side, two storey side & internal alterations
Guildford
· Semi Detached
· 2023
£97k
· Jun '24
Ground floor side, internal alterations & garage conversion
Wokingham
· Detached
· 2024
£128k
· Jul '24
Ground floor side, garage conversion & first floor side
Windsor and Maidenhead
· Semi Detached
· 2026
£147k
· Feb '26
Ground floor side and internal alterations
Elmbridge
· Detached
· 2022
£105k
· Jan '23
AI images
Images are AI-generated for homeowner privacy
Ground floor side and garden annex
Southampton
· Semi Detached
· 2025
£74k
· Oct '24
Loft main dormer and ground floor side
Elmbridge
· Detached
· 2025
£356k
· Jul '24
Ground floor rear and ground floor side
Richmond upon Thames
· End Of Terrace
· 2023
£120k
· Mar '23
Ground floor side and internal alterations
Mid Sussex
· Semi Detached
· 2022
£103k
· Mar '22
AI images
Images are AI-generated for homeowner privacy
