When completing or supporting an EWS1 form, intrusive surveys are often necessary to inform fire assessors of the building risks associated with façade materials and their make-up, and how those materials relate and react to each other. This information is required to properly understand the external wall construction and to carry out a fire risk assessment that reflects the building as constructed.

Drawings, as-built information and historical records do not usually provide fire assessors with enough reliable information about façade make-up. Changes are frequently made on site during construction due to material availability and cost pressures, and these are not always recorded on construction drawings or updated in final records. Visual inspections can confirm surface materials, but they do not allow a full appraisal of the through wall construction or how different components relate to one another. Without confirmation of the full construction, assumptions may be made that affect the outcome of the assessment.

Intrusive surveys confirm the full through wall construction of the external wall. This allows a risk assessed approach to determining the correct EWS1 rating based on verified information rather than assumption. Intrusive investigations commonly identify issues such as missing or incorrectly fitted fire barriers, components that differ from those specified or shown on drawings, non-fire protected steelwork, missing or non-fire rated sheathing boards or membranes, and inadequately protected service penetrations.

By confirming how the building has actually been constructed and the materials used, intrusive surveys reduce uncertainty and challenge assumptions that may otherwise be made due to limited or unreliable records. Where intrusive surveys are not undertaken, there is a risk that incorrect conclusions are reached, including the adoption of an inappropriate EWS1 rating.

From a building owner’s perspective, intrusive surveys provide the clearest understanding of how a building has been constructed and the materials used. As as-built information is not always available and construction changes often occur on site, intrusive surveys remove doubt around construction methods and materials and support clearer, more defensible EWS1 decisions.

How FRC can help

FR Consultants carry out intrusive surveys to confirm external wall construction and support fire risk assessment and EWS1 decision making. Our services include:

  • Intrusive surveys of external wall systems
  • Confirmation of façade materials and through wall construction
  • Identification of construction issues affecting fire risk
  • Provision of survey information to support EWS1 assessments