How SashMark works

Enter the postcode and exact house number or name. We validate the location and try to match records to the property. Flat identifiers matter: records for another home in the same building must not silently become evidence for yours.

Where a confident property match is available, it can improve the location used for checks. Where only a postcode location is available, the report identifies the reduced precision. Area evidence is not automatically a finding about the building.

• HM Land Registry and UK HPI: recorded transactions and wider market movement. Nearby sales are not necessarily equivalent homes.
• Energy Performance of Buildings data: certificate details where an address match is confident. Assessment dates and subsequent alterations matter.
• Planning Data and local records: available constraints and applications. Publication and geographical coverage vary.
• Environment and geospatial datasets: mapped screening evidence with source-specific resolution and limits. Read the individual source notes.
• Police.uk, DfE and Ofsted: reported incidents and school information. These describe the available records, not a guarantee of personal safety or a school place.
• Connectivity sources: availability information where configured and supported. Confirm service at the exact address with the provider.

Some official records can also be checked directly using the sold-price search and energy-certificate service. SashMark adds organisation and interpretation rather than claiming exclusive access to public records.

The 0–100 score summarises assessed indicators. Higher means the available evidence raises fewer issues under the model. It is a screening aid, not a recommendation to buy or a guarantee of condition.

Property, planning, environment, area/crime and connectivity contribute when sufficiently supported. Unavailable categories are excluded and remaining weights are renormalised. Schools are informational. Market evidence supports coverage and valuation confidence rather than a property-quality score.

Coverage is shown separately. Below 50% coverage, the overall result is labelled preliminary. Compare the underlying findings and coverage before comparing headline scores: different available evidence can change which categories are averaged.

Where evidence permits, SashMark combines a confidently matched previous sale adjusted using local house-price movement, nearby comparable transactions and a floor-area method. Each method needs suitable evidence and is weighted according to its quality.

Sparse, old, distant or conflicting evidence increases uncertainty. A range reflects that uncertainty; it is not a mortgage valuation, surveyor’s valuation or guaranteed sale price. The model cannot directly observe the current finish, hidden defects or all alterations.

Sources can return no usable record, fail temporarily or require a service connection. These states are distinguished in the report. We do not substitute example data into a live property search. The example report is separately labelled.

Read retrieval dates alongside any underlying dataset or assessment date. Retrieving a source today does not make every record current. A map boundary near a property, a postcode-level location or incomplete council coverage may warrant a more precise follow-up.

Use the report to identify what to ask the seller, agent, surveyor or conveyancer. Confirm material findings against the relevant original record and seek professional advice on what they mean for the transaction. Read our service background and contact details if you need help or want to flag an error.