If you're buying a flat in the UK, there's a decent chance someone will say the words "EWS1 form" at you, usually at the worst possible moment. Normally right after your offer's accepted, and normally without much explanation.

Here's the plain version.

What an EWS1 form actually is

EWS1 stands for External Wall System 1. It's a one page form that records a qualified professional's assessment of the external walls of a block of flats, specifically whether the materials used are a fire risk.

It came out of Grenfell. In December 2019, RICS, UK Finance and the Building Societies Association introduced it because lenders had effectively stopped lending on flats in buildings with cladding. Valuers couldn't price the risk, so they were valuing flats at nil. The form gave them something to work with.

Two things people get wrong about it constantly:

It isn't a safety certificate. An EWS1 doesn't say your building is safe, and it isn't a legal requirement. It's a valuation tool. It exists so a mortgage lender can decide whether to lend.

It covers the whole building, not your flat. One form, one building. If a neighbour has already had one done, that's your form too. It's valid for five years from the date it's signed.

The ratings, in English

There are two options, A and B, and five outcomes.

Option A is for buildings where the external wall materials are unlikely to support combustion.

A1 means no combustible materials in the external walls. Cleanest possible outcome.
A2 means there's some combustible material, but it's in a system that doesn't need work.
A3 means combustible materials are present in balconies or similar, and some remediation may be needed.

Option B is for buildings where combustible materials are present and a fire engineer has had to appraise the actual risk.

B1 means the risk is low enough that no remediation is needed.
B2 means remediation is required.

A1, A2 and B1 are the ones that make lenders comfortable. A3 and B2 mean work is needed, and that's where things get slow and expensive.

When you'll actually be asked for one

Less often than you'd have been in 2021, and this is the bit that's changed most.

At the peak, EWS1 requests were being made on buildings of any height, including low rise blocks with no cladding at all. It was chaos. Roughly half a million flats were reckoned to be unsellable.

Several things loosened it up:

In January 2021 RICS published guidance setting out when a form should and shouldn't be requested, which pushed back on blanket requests for low rise buildings.
In July 2021 the government withdrew its consolidated advice note, and PAS 9980 later replaced it with a proper risk appraisal method.
The Building Safety Act 2022 brought in leaseholder protections, capping or removing what qualifying leaseholders can be charged for cladding remediation.
Following that, the major lenders agreed to consider lending on flats in affected buildings where there's a credible remediation plan or the leaseholder protections apply, rather than demanding an EWS1 in every case.

So the practical position now: an EWS1 is most likely to come up on taller buildings with cladding or combustible balconies. It's much less likely on a low rise brick block. But "less likely" isn't "never", and individual lenders and individual valuers still vary. Your broker will know their specific lender's line better than any general article, including this one.

One more thing worth knowing: an EWS1 isn't always the only option. RICS has confirmed that in some cases a summary report from a PAS 9980 fire risk appraisal of external walls can be relied on instead, as long as it gives a clear answer on whether remedial work is needed and it's signed by a suitably qualified professional. If your building has had a FRAEW done, ask whether that'll satisfy the lender before anyone commissions a fresh EWS1.

What changes on 1 November 2026

RICS has published a second edition of its standard for valuing flats in multi storey buildings with cladding, and it takes effect on 1 November 2026.

The point of it is to stop unnecessary requests. It sets out proportionate criteria for when a valuer should actually ask for an EWS1, with different thresholds depending on whether a building is over six storeys, five to six storeys, or four or fewer. The triggers are things like building height, whether there's visible cladding, curtain wall glazing, and how the balconies are built.

If you're buying in late 2026 or after, this is good news. Fewer buildings should get caught by a reflex request.

Longer term, RICS expects the form to fade out entirely, because external walls now have to be assessed as part of the fire risk assessment for residential blocks anyway. The EWS1 was always a stopgap.

Who pays

Not you, at least not directly.

The form is commissioned by whoever's responsible for the building, usually the freeholder or the managing agent. An individual leaseholder can't just order one for their own flat, and you shouldn't be asked to pay for one as a condition of your purchase.

The caveat: costs incurred by the building owner can sometimes find their way into the service charge. The Building Safety Act protections limit what qualifying leaseholders can be charged for remediation itself, but the picture around surveys and associated costs is messier. Worth asking directly what's been charged historically.

What to do if the flat you want doesn't have one

Ask these, in this order, before you spend money on a survey or searches.

Does an EWS1 exist for this building, and what's the rating? The managing agent or freeholder will know. Ask for a copy, not a summary.
If there's no form, has the lender actually asked for one? Sometimes the agent raises it pre emptively and the lender doesn't care. Find out before you panic.
If one is needed, has it been commissioned, and when's it expected? Waits have shortened a lot since 2021, but a building at the back of a queue can still stall a purchase for months.
If the rating is A3 or B2, what's the remediation plan and who's funding it? Government funding schemes and developer pledges cover a lot of buildings, but not all. This is the question that decides whether the purchase is viable.
Ask your broker which lenders are comfortable with this specific building. Lender appetite varies more than anything else in this process.

The honest summary

EWS1 is a mortgage problem dressed up as a safety document. For most buyers, on most buildings, it now won't come up. If it does, the rating and the remediation plan matter far more than the existence of the form itself.

And if you're looking at flats in a block where nobody can give you a straight answer about the external walls, treat the vagueness itself as information.

This is general information, not legal, financial or mortgage advice. Building safety rules and lender policy have changed repeatedly since 2019 and continue to change. Check the current position with your conveyancer and mortgage broker before making a decision.