Barnet, London
Boroughs · North London
Barnet · Outer London

House extensions in Barnet

Big plots, forgiving planning and side access make Barnet one of the most cost-efficient boroughs for a full wraparound or double-storey rear.

Typical all-in (inc VAT)
£95k–£155k
Cost vs London base
On par
Postcodes covered
EN5 · N3 · N12 · NW4

Housing stock in Barnet

Interwar semis, 1930s Metroland, larger detached villas in Totteridge and Hampstead Garden Suburb.

WraparoundDouble-storey rearLoft conversion

Planning in Barnet

Barnet operates fairly standard suburban planning; most side and rear extensions land under permitted development or a straightforward householder application. Hampstead Garden Suburb is the notable exception with its own conservation regime.

Party Wall Act — what to expect

Semi-detached stock means one party wall — much cheaper Award process than inner London terraces.

Read the Party Wall etc. Act 1996 guide for full detail on notices, timelines and surveyor costs.

Typical costs in Barnet

For a mid-spec 25 m² kitchen extension, all-in (professional fees, planning, party wall, VAT and 12% contingency), expect roughly £95,000 to £155,000. High-spec finishes, structural glazing or a full basement dig-out will push above the top of this range; a smaller side-return can come in under the bottom.

Cost tier
Outer London · Baseline vs London average

Our calculator applies a 1.00× multiplier automatically for Barnet projects. Get an itemised breakdown in 60 seconds.

Get your Barnet estimate

Areas we cover in Barnet

EN5N3N12NW4NW11HA8

Why homeowners in Barnet pick us

  • KYB-verified builders only
  • Local Barnet project experience
  • Fixed, itemised written quotes
  • Full insurance & warranty checks
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