Building standards - managing fire risks associated with use of external wall systems: research

10. Appendix

Stage A: Materials / Datasheets

Start

A1. Have material datasheets/test data been provided for all components of all wall types? (See Checklist 1) Yes – Go to A2; No – Stop assessment. Request all information listed in Checklist 1

A2. For the material assessed, is it a fire barrier in line with a compartment/separating wall or floor? Yes – Go to A3; No – Go to A4

A3 Does the fire resistance period in the manufacturer’s literature match the fire rating of the compartment/separating wall or floor? Yes – Go to A8; No – Go to A.i

A4. For the material assessed, is it a cavity barrier around openings? Yes – Go to A5; No - Go to A7

A5. Does the cavity barrier meet List a-d from note 3 of Table 2.19 of NDTH/ or Table 2.7 of DTH/? Yes – Go to A8; No – Go to A6

A6. Is there evidence in the manufacturer’s literature to show that the cavity barrier tested to achieves at least 30 minutes fire resistance? Yes – Go to A8; No – Go to A.i

A7. For each material, is the material exempted as outlined in Annex 2.E.2 of the Non-Domestic Technical Handbook or Annex 2.B.2 of the Domestic Technical Handbook or by EC/ 96/603/EC/? Yes – Go to A8; No – Go to A.i

A8. The material is acceptable.

A.i Are datasheets/test data for the material assessed up to date and appropriate for the proposed build-up? Yes – Go to A.ii; No – Stop assessment. Request appropriate data sheets/test data

A.ii Does the performance on the datasheet confirm European Classification A1 or A2? Yes – Go to Aiii; No – Go to A.iv or B.i

A.iii The material is acceptable.

A.iv The material is not appropriate. Reject the proposal and state the reason for rejection.

End

The Stage A decision process is represented visually in Figure X below.

Notes on Stage A:

A1. Without all of the information available, it is possible to arrive at incorrect conclusions. Therefore, the local authority verifier should first request all of the information in Checklist 1 before proceeding with their assessment. If upon commencing the assessment the local authority verifier discovers that information on Checklist 1 is missing, they should cease their assessment and request the information from the design team.

A2. This step is to direct the verifier to the correct assessment method. The process should be repeated for each material assessed. In this Guidance Tool, a fire barrier is a material in line with a compartment/separating wall or floor.

A3. Fire barriers in line with compartment/separating walls and floors should achieve at least the same fire resistance period as the compartment/separating wall or floor.

A4. No notes provided

A5. No notes provided

A6. No notes provided

A7. No notes provided

A8. No notes provided

Ai. No notes provided

Aii. European Classification A1/A2 is defined in the Technical Handbooks

Aiii. No notes provided

Aiv. No notes provided

Stage B: Design Drawings

Start

B1. Have all drawings been provided for review? (See Checklist 2) Yes – Go to B2; No – Stop assessment. Request all information listed in Checklist 2

B2. Are fire barriers shown in line with:

B2.1 Compartment Walls?

B2.2 Compartment Floors?

B2.3 Separating Walls?

B2.4 Separating Floors?

Yes to all – Go to B3; No to any – Go to B.i

B3. Do the fire rating of the fire barriers match the fire rating of the:

B3.1 Compartment Walls?

B3.2 Compartment Floors?

B3.3 Separating Walls?

B3.4 Separating Floors?

Yes to all – Go to B4; No to any – Go to B.i

B4. Do the fire barriers in line with compartment/separating walls/floors extend through to the outermost component of the external wall systems? Yes – Go to B5; No – Go to B.i

B5. Do the proposed uses of the fire barriers in line with compartment/separating walls/floors align with the manufacturer’s literature in A3? Yes – Go to B6; No – Go to B.i

B6. Are cavity barriers shown around the following:

B6.1 Window openings?

B6.2 Door openings?

B6.3 Service penetrations?

Yes to all – Go to B7; No to any – Go to B.i

B7. Do these cavity barriers meet List a-d from note 3 of Table 2.19 of NDTH/ or Table 2.7 of DTH/? Yes – Go to B9; No – Go to B8

B8. Do the proposed uses of the cavity barriers around façade openings align with the manufacturer’s literature in A6? Yes – Go to B9; No – Go to B.i

B9. The design drawings is acceptable

B.i Have any fire engineering assessments been proposed to support this arrangement? Yes – Go to B.ii; No – Go to B.vi

B.ii Is the local authority verifier suitably competent to pass judgement on fire engineering proposals? Yes – Go to B.iii; No – Go to B.iv

B.iii Is the proposal reasonable, i.e. does it meet the Technical Handbook’s functional standard (s)? Yes – Go to B.v; No – Go to B.vi

B.iv Seek guidance from a competent colleague or suitably qualified third party e.g. Fire Engineer with CEng status through IFE/ with sufficient external wall fire testing experience. Go to B.iii

B.v The design is acceptable

B.vi The design is not appropriate. Reject the proposal and state the reason for rejection.

End

The Stage B decision process is represented visually in Figure Y below.

Notes on Stage B:

B1. Without all of the information available, it is possible to arrive at incorrect conclusions. Therefore, the local authority verifier should first request all of the information in Checklist 2 before proceeding with their assessment. If upon commencing the assessment the local authority verifier discovers that information on Checklist 2 is missing, they should cease their assessment and request the information from the design team.

B2. Fire barriers should be provided in the external wall system in line with compartment/separating walls and floors to continue the fire resistance of the compartment/separating wall/floor through to the outside of the external wall system.

B3. See note to B2.

B4. See note to B2.

B5. Fire barriers need to be fire rated, and the fire resistance should be based on test data provided on a datasheet.

B6. If the answer is no to any, the impact of cavity barriers not being provided needs to be considered holistically. This applies regardless of the extent/quantity of the omitted cavity barriers, fire engineering justification would need to be provided in order for the local authority verifier to consider the impact of the cavity barrier omission on the whole external wall system.

B7. No notes provided

B8. Cavity barriers need to be fire rated, and the fire resistance should be based on test data provided on a datasheet (with the exception of the items noted in B7).

B9. No notes provided

Bi. Appropriate fire engineering justification would need to be provided to justify a “no” answer to B2, B3, B4, B5, B6, or B8.

Bii. It is important to acknowledge where the local authority verifier is not suitably trained or qualified to assess a fire engineering design. The authors’ view is that a suitable demonstration of competence could include Incorporated Engineer and Chartered Engineer level with the Institution of Fire Engineers. These qualifications require the holder to demonstrate the experience in the field and analytical thinking required to assess fire engineering proposals.

Biii. The requirement is to meet the functional standards in the I as the minimum acceptable performance criteria.

Biv. No notes provided

Bv. No notes provided

Bvi. No notes provided

Stage C: Site Inspections

Materials

Start

C1. Is there a record on purchase order for the components of the external wall system on site? Yes – Go to C3; No – Go to C2

C2. Is there onsite photographic evidence clearly showing the brand and references of all the components of the external wall system? Yes – Go to C3; No – Request further evidence for C1.

C3. Does the evidence in C1 and C2 match the technical datasheets reviewed in A? Yes – Go to C4; No – Please note the variations and re-start Section A.

C4. Do the observations made on site (see Checklist 3 for sampling points) match the wall build up drawings reviewed in Section B? Yes – Go to C5; No – Please note the variations and re-start Section B.

C5. The materials installed on site and external wall built up matches design drawings design information. Go to C6.

End

Cavity/Fire Barriers

Start

C6. Have the cavity/fire barrier inspections been carried out by an independent third party company accredited/endorsed by the cavity/fire barriers manufacturer? Yes – Go to C8; No – Go to C7

C7. Local authority to carry out a site inspection. Do the observations made on site (see Checklist 3 for sampling points and Checklist 4 for cavity/fire barrier measurement) match with the manufacturers’ product literature for the installation of cavity/fire barriers? Yes – Go to C10; No – Go to C11

C8. Did the independent third party company inspect all the items in Checklist 4 i.e.: junctions with compartment/separating walls, junctions with compartment/separating floors; cavity barriers around windows, doors, and service openings; cavity barriers at wall heads? Yes – Go to C9; No – Go to C7 to inspect areas not covered by the independent third party.

C9. Did the independent third party company confirm their suitability in writing? Yes – Go to C10; No – Please ask for the confirmation in writing.

C10. As built cavity/fire barriers installation is acceptable.

C11. As built cavity/fire barrier installation is not appropriate. Reject the proposal and state the reason for rejection.

The Stage C decision process is represented visually in Figure Z below.

End

The Stage C decision process is represented visually in Figure Z below.

Notes on Stage C:

C1. Purchase orders for components in the external wall systems will allow the local authority verifier to confirm that the same materials assessed in Stages A and B are likely to have been installed on site. This will also allow the local authority verifier to identify any new materials/components that were not assessed in Stages A and B.

C2. Photographic evidence should be recorded by the installer to evidence that the construction materials are those assessed in Stages A and B. The photographic evidence should clearly identify where the photograph was taken e.g. with a drawing reference key.

C3. Any discrepancies between the assessment carried out by the local authority verifier in Stages A and B and the on-site evidence could compromise the conclusions of the Stages A and B assessment. Therefore, the assessment should be undertaken anew.

C4. Any discrepancies between the assessment carried out by the local authority verifier in Stages A and B and the on-site evidence could compromise the conclusions of the Stages A and B assessment. Therefore, the assessment should be undertaken anew.

C5. No notes provided

C6. The following are not considered to be suitably independent

a. Interviews with installers (no self-certification permitted)

b. The contractor’s/sub-contractor’s own QA/

c. The contractor’s QA/ of their sub-contractor

d. Photos only

C7. The local authority verifier’s site inspection should take into consideration the recommendations in Checklist 4.

C8. No notes provided

C9. No notes provided

C10. No notes provided

C11. No notes provided

Checklist 1 – Expected Components Of External Wall Systems

Please refer to PAS/ 9980 Annex L “Element” column for common external wall system materials/components.

External wall systems are defined in 2.7.1 of the Technical Handbook as: “non load-bearing components attached to the buildings structure, for example, composite panels, clay or concrete tiles, slates, pre-cast concrete panels, stone panels, masonry, profiled metal sheeting including sandwich panels, rendered external thermally insulated cladding systems, glazing systems, timber panels, weather boarding and ventilated cladding systems. For the purposes of compliance with the building regulations and associated standards, external wall cladding systems also include spandrel panels and infill panels. Many systems incorporate support rails, fixings, thermal insulation, fire barriers and cavity barriers located behind the outer cladding.” For clarity, it is the view of the authors that timber supports are also part of the external wall systems, including in timber frame buildings; in these buildings the elements of structure could be timber (where permitted by building regulations) however any other construction supporting the external wall system that are not elements of structure would need to be non-combustible.

Elements of structure are defined in 2.3.1 of the Technical Handbook.

Checklist 2 – Drawing And Design Information

• Fire Strategy Plans
• Fire Strategy Elevations
• Drawings showing the build up of all the “as built” external wall types
• Plan and section drawings showing cavity/fire barrier details including:
  • Cavity barriers installed around doors
  • Cavity barriers installed around windows
  • Cavity barriers installed at the wall head
  • Cavity barriers installed around ventilation ductwork that penetrates through external walls
  • Fire barriers in line with compartment walls
  • Fire barriers in line with compartment floors
  • Fire barriers in line with separating walls
  • Fire barriers in line with separating floors
  • Fixing details
• Is a ventilated cavity system proposed?
• Qualifications and experience of person(s) certifying any changes from the tested assembly
• Qualifications and experience of person(s) certifying the application of the system to the proposed configuration
• Drawings showing the build up of all the “as built” external balcony/terrace details
• Any local authority verifiers’ agreement on designs that deviate from the Technical Handbooks standard cavity barrier requirements.

Checklist 3 – Site Inspections Sampling Points

At least 2 instances of each wall type to confirm composition reflects Section B design review

At least 2 instances of each of the following critical locations for each wall type:

• Compartment walls (vertical fire barriers)
• Compartment floors (horizontal fire barriers)
• Window head
• Window jamb
• Window cill
• Service penetration
• Wall head

Checklist 4 – Site Inspection Measurement (Cavity/Fire Barriers)

Check the following against the manufacturer’s product literature:

• Thickness of cavity/fire barriers and their associated fire rating
• Depth of the cavity/fire barriers against the depth of the cavity
• The requirement for brackets/fixings on cavity/fire barriers against the depth of the cavity barriers
• Number of brackets/fixings per cavity/fire barrier
• Distance between brackets/fixings
• The method of fixing the brackets compared to the product literature recommendations
• For closed state cavity/fire barriers – the extent of compression required
• For open state cavity/fire barriers – the maximum air gap permitted by the manufacturer
• Any other information on the manufacturer’s product literature

Commentary On Development Of Guidance Tool

After Grenfell, the Royal Institution of Chartered Surveyors (RICS/) in conjunction with the Building Societies Association and UK/ Finance produced the EWS/1 form. This was created as a means for valuers and lenders to have it confirmed to them that an external wall system or attachments, such as balconies, on buildings containing flats has been assessed by a suitable expert.

As fire engineers, the author’s primary expertise is with proposals that do not achieve straightforward compliance. After the creation of the EWS/1 form, the authors were faced with reviewing external wall systems with unusual configurations and/or unknown fire performance.

Although the Grenfell tragedy occurred in an area governed by The Building At 1984 and 2000 Building Regulations in force in England and Wales, the EWS/1 form is currently being demanded by valuers and lenders/funders for tall domestic buildings and any domestic buildings with cladding throughout the UK/. In the authors’ experience, many developers were also seeking to obtain an EWS/1 form even for low rise domestic buildings with conventional brick external wall systems primarily to meet their funders’ requirements for having an EWS/1 form. Therefore, the demand for EWS/1 forms increased from addressing buildings with, for example, small sections of combustible materials to most buildings containing flats.

The below are typical problems that the authors have identified on buildings where they have carried out EWS/1 form desktop studies and site inspections:

• Lack of design information being available
• Substitutions of products/materials being made by the contractor team after the Building Warrant has been approved
• Fire barriers not completing the line of separating/compartment walls/floors all the way through the external wall system
• Details being approved at the Building Warrant stage without products being specified e.g. “mineral wool insulation by others”, leading to a lack of oversight
• Cavity/fire barriers not being installed on site not in line with the manufacturer's literature e.g. not deep enough to fill the cavity, missing brackets, distances between brackets being too large
• Cavity/fire barriers being missed completely
• Materials on site not reflecting the approved design information
• Systems being installed on site that don’t reflect the manufacturer's literature
• A lack of justification/reasoning as to why certain products with a lower standard of classification than permitted by the Building Regulations are installed on the cladding system. This includes:
  • Timber cladding
  • High Pressure Laminate (HPL/) cladding panels
  • Metal Composite Materials (MCM/) panels
• A lack of consideration of the fire spread potential of constructing balconies from combustible materials.

Some of these items can be resolved with fire engineering assessments by a competent person, others require mitigation/replacement on site.