What Is a Strategic Housing Land Availability Assessment (SHLAA)?

Strategic Housing Land Availability Assessment or SHLAA is a study that every local authority must undertake and provides an overview of the potential residential or employment-related development sites within each authority boundary.

Understanding how SHLAA works is essential for property developers, land promoters, and investors looking to align their strategies with local planning policy.

What Is the Purpose of a SHLAA?

The SHLAA study is a leading indicator of the authority's available land for development and can also identify if the council is behind its housing target. The SHLAA informs plan-making by doing three things:

• It identifies sites that have the potential for new housing
• It assesses how many homes they may accommodate
• It estimates when these sites, if suitable, are likely to be developed

‍However, the assessment does not in itself determine if a site should be allocated for development but provides information on the range of sites which are available to meet the local authority’s requirements.

How Does the SHLAA Process Work?

While the exact methodology may vary between local authorities, the SHLAA process typically follows these key stages:

1. Call for Sites

Councils begin with a public “Call for Sites,” inviting landowners, developers, and other interested parties to submit land parcels for assessment. This results in a long list of potential sites.

2. Initial Assessment

Each submitted site is assessed against key thresholds and constraints, which might include:

• Minimum site size
• Deliverability (e.g. access, infrastructure)
• Local planning policy alignment
• Environmental or heritage constraints

3. Shortlisting

Sites that meet the criteria are shortlisted and included in the SHLAA report. Being shortlisted doesn’t guarantee delivery - only that the council considers the site potentially suitable for development.

4. Publication and Review

The SHLAA is published and periodically updated - typically every 1–5 years - giving developers ongoing insight into land supply.

Example: How Sites Are Assessed in the London SHLAA

The London SHLAA, led by the Greater London Authority (GLA), assesses:

• Large sites (0.25 hectares and above)
• Small site capacity (below 0.25 ha), based on borough-level assumptions

Sources for large site identification include:

• Previous SHLAA reports
• Local development plans
• Sites with planning permission
• Call-for-sites submissions
• GLA-led capacity studies

Sites are then mapped, assessed for potential, and categorised based on planning and physical deliverability.

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What SHLAA Data Includes

Each SHLAA entry typically includes:

• Site name and location
• Decision status (e.g. Deliverable, Developable, Not Developable)
• Estimated housing capacity (units)
• Development timeframe (e.g. 0–5 years, 6–10 years)
• Reason for decision (explaining site suitability or constraints)

This data helps paint a full picture of whether and when land could realistically support development.

Why Is SHLAA Important for Developers?

For land promoters and property developers, the SHLAA offers:

• Early visibility of potential housing sites
• Insight into council land supply and housing targets
• Direction for off-market site acquisition
• Evidence to support planning applications and appeals

By identifying sites the council already considers suitable in principle, developers can reduce planning risk and better align their projects with local housing needs.

Where to Access SHLAA Data in the UK

Information about SHLAA sites is available online, as local authorities are required to publish their assessments and site lists. However, each council presents this data differently, ranging from PDFs to spreadsheets, making it difficult to navigate and search through the documents. Tools like Searchland, which organise and standardise the data, are incredibly useful for making this process easier and more user-friendly.

SHLAA-Based Site Sourcing: Smarter Land Strategy

Using SHLAA as part of your land acquisition strategy allows you to:

• Identify off-market development land
• Target sites more likely to gain planning approval
• Filter by decision status and delivery timeframe
• Combine with demographic and infrastructure data for strategic targeting

Want to learn more about a SHLAA-based land acquisition strategy? Read our blog.