Guide · EWS1 B1
What does an EWS1 B1 rating mean?
A quick, plain-English answer for leaseholders, buyers and agents, with what a B1 means for a sale or remortgage.
In short: an EWS1 B1 rating means combustible materials are present in the external wall, but a fire safety professional has concluded that the fire risk is low enough that no remedial works are required. For most buyers, sellers and lenders, B1 is a satisfactory outcome.
What B1 means on the form
The EWS1 form has two options. Option A is for walls whose materials are unlikely to support combustion. Option B is used where combustible materials are present, and has two outcomes:
- B1: the signatory has concluded the fire risk is sufficiently low that no remedial works are required.
- B2: the signatory has concluded that remedial and interim measures are required. See EWS1 B2 rating explained.
So a B1 does not mean the building has no combustible materials. It means a qualified person has looked at what is there, and at the building as a whole, and judged the risk acceptable without works.
Is a B1 rating bad?
No. A B1 confirms that no remedial works are needed. Lenders set their own policies, but B1, like A1 and A2, generally indicates that the external walls should not affect the valuation.
Who can sign a B1
Option B needs more fire expertise than Option A. It must be signed by a member of a professional body that deals with fire safety in the built environment, because the signatory is making a fire risk judgement rather than confirming the walls are made of materials unlikely to burn.
How a B1 is reached
The EWS1 is normally signed on the strength of a FRAEW to PAS 9980 (see what is a FRAEW?). The FRAEW establishes what the walls are made of, often by opening them up, and assesses the risk. Where the risk is acceptable without works, a B1 follows.
Our Christ's Lane, Cambridge case study is an example: four wall systems were opened up and appraised on a mixed-use city-centre block, giving a Low overall risk rating and an EWS1 B1 outcome.
How long a B1 lasts
An EWS1 form is valid for up to five years, unless the building changes or new information comes to light. If works are carried out to the external walls, a new assessment may be needed.
Do you still need an EWS1 at all?
From 1 November 2026, the RICS standard for mortgage valuations says valuers should only ask for an EWS1 where there is a clear reason to, and in some cases a FRAEW summary can be relied on instead. Read What is an EWS1 form?
Frequently asked questions
What does EWS1 B1 mean?
B1 means combustible materials are present in the external wall, but the signatory has concluded the fire risk is sufficiently low that no remedial works are required.
Is a B1 EWS1 rating good or bad?
It is a satisfactory outcome. It confirms that no remedial works are needed, and lenders generally treat it in the same way as A1 and A2.
What is the difference between B1 and B2?
Both apply where combustible materials are present. B1 means no remedial works are needed. B2 means remedial and interim measures are required.
How long is a B1 EWS1 valid?
Up to five years, unless the building changes or new information comes to light.
Related reading
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