Cladding and EWS1: How Building Safety Issues Affect Flat Values

For flats in taller buildings, building safety status can matter more to mortgageability — and therefore value — than almost anything a comparable-sales figure can capture.

The post-Grenfell context

Following the Grenfell Tower fire, UK building safety regulation tightened significantly, particularly around external wall systems (cladding) on buildings above certain height thresholds. Many buildings built or clad before the new standards required reassessment, and in some cases remediation, before they could be confirmed safe under current rules.

What an EWS1 form is

An EWS1 (External Wall System) form is a standardised assessment, carried out by a suitably qualified professional, confirming whether a building's external wall system meets current safety standards. Many mortgage lenders require a satisfactory EWS1 rating before they will lend on a flat in an affected building, regardless of how strong the flat's own comparable sales data looks.

The practical effect on value

A flat in a building without a satisfactory EWS1 (where one is required) can become effectively unmortgageable to most buyers, which collapses the buyer pool to cash purchasers only and puts severe downward pressure on the achievable price — often a much larger effect than any physical defect in the flat itself would justify.

The Building Safety Act 2022 and leaseholder protection

The Building Safety Act 2022 introduced significant protections limiting how much of the cost of remediating historical building safety defects can be passed on to qualifying leaseholders, and established routes (including the Building Safety Fund and developer remediation pledges) for funding fixes without the full cost landing on individual flat owners. This has meaningfully improved the position for many affected leaseholders since the immediate post-Grenfell period, though the practical position still varies a great deal building by building.

Why this sits outside what a comparable-sales tool can see

Building safety status is specific to the individual building, not the wider postcode sector, so a tool like this one — which prices from comparable sold prices across an area — cannot capture it. Before relying on any valuation figure for a flat in a building over roughly 11 metres or five storeys, check directly with the managing agent or freeholder for the building's current EWS1 status, similar in principle to checking lease length and service charge exposure before valuing a leasehold flat.

Frequently asked questions

What is an EWS1 form?

A standardised External Wall System assessment, carried out by a suitably qualified professional, confirming whether a building's external cladding and wall system meet current fire safety standards.

Why does EWS1 status affect a flat's value so much?

Many mortgage lenders will not lend on a flat in a building without a satisfactory EWS1 where one is required, which restricts buyers to cash purchasers only and can severely depress the achievable price regardless of the flat's own condition.

Does the Building Safety Act 2022 protect leaseholders from remediation costs?

It introduced significant protections limiting how much historical building safety remediation cost can be passed to qualifying leaseholders, and created funding routes such as the Building Safety Fund, though the practical position still varies building by building.

Can a comparable-sales valuation tool detect building safety issues?

No. Building safety status is specific to the individual building rather than the wider postcode sector, so it falls outside what any area-based comparable-sales estimate can capture. Always check directly with the managing agent or freeholder.