Harrow, London
Boroughs · West London
Harrow · Outer London

House extensions in Harrow

Classic Metroland stock: big semis, side access and forgiving planning — some of the cheapest per-sqm builds inside the M25.

Typical all-in (inc VAT)
£90k–£145k
Cost vs London base
-3%
Postcodes covered
HA1 · HA2 · HA3 · HA5

Housing stock in Harrow

1930s Metroland semis and detached, larger Arts & Crafts in Pinner.

WraparoundDouble-storey rearLoft

Planning in Harrow

Pinner and Harrow-on-the-Hill conservation areas add design review. Elsewhere Harrow is a very PD-friendly borough.

Party Wall Act — what to expect

Semi-detached: one party wall neighbour typical.

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

Typical costs in Harrow

For a mid-spec 25 m² kitchen extension, all-in (professional fees, planning, party wall, VAT and 12% contingency), expect roughly £90,000 to £145,000. 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 · -3% vs London average

Our calculator applies a 0.97× multiplier automatically for Harrow projects. Get an itemised breakdown in 60 seconds.

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Areas we cover in Harrow

HA1HA2HA3HA5HA7

Why homeowners in Harrow pick us

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