PropeteerProperty intelligence

Buyer guide

Buying a property to extend

Assess the purchase and the project together: planning evidence, target floor area, completed-home comparables, realistic costs and local ceiling. A cheap property is not an opportunity if the scheme is unlikely or the market will not support the result.

Written and reviewed by Propeteer Research TeamPublished Reviewed

At a glance

Key facts

Planning case
Similar decided schemes plus site constraints
Value case
Sales of the completed target property
Delivery case
Survey, design, cost, programme and contingency

A reliable process

How to approach the question.

  1. 01Define the proposed works and target home before valuing uplift.
  2. 02Research local planning outcomes and restrictions.
  3. 03Compare completed homes of the target size and type.
  4. 04Stress-test all-in cost, delay, refusal and resale scenarios.

Worked example

Doubling a small house

A model should value the larger completed home, not apply a generic extension percentage. It should also test whether the scheme creates awkward space, loses garden, exceeds local precedent or breaches the street’s value ceiling.

What this does not prove

  • Planning and value evidence can change before completion.
  • Early costs should be treated as ranges.
  • Finance, tax and personal risk tolerance require separate advice.

Method used

  • Start with the exact address and stable property identifiers so records for neighbouring or subdivided homes are not merged.
  • Separate open-data screening from formal conveyancing searches, surveys and professional opinions.
  • Record what was checked, when it was checked and whether the result means clear, no match, unavailable coverage or a failed connection.

Primary sources and official guidance

How to buy a homeMinistry of Housing, Communities and Local GovernmentPlanning PortalPlanning PortalPrice Paid DataHM Land Registry

Source scope, licensing, refresh expectations and known limitations are listed in the public data-source register.

Related guides

Property due-diligence checklist

A practical checklist covering property identity, planning, valuation, survey, title, searches, environment, services and local context.

Questions to ask before making an offer

Ask focused questions about ownership, tenure, alterations, condition, services, neighbours, chain and evidence behind the asking price.

Apply this guide

Start with the exact UK address.

Research a property