Project Team – Competent Person(s)
Part L2: 2002 of Building Regulations (England and Wales) introduced site testing of the building envelope to confirm compliance with the design for thermal insulation and air leakage. Where infra-red thermography and/or air leakage testing are to be carried out on completion of the building it will be expensive to rectify any defects found, it is therefore essential that the whole project team, of designer, main contractor and sub-contractors work together to achieve full Part L2 compliance at the design and construction stages and therefore, meet the project's energy efficiency and Carbon Dioxide (CO2) emission targets.
During design, tendering and building control applications it is likely that the architect, designer or independent specialists will be the competent person(s) for achieving compliance with thermal insulation and air leakage requirements of Part L2.
Specialists may be required especially on larger complex projects to provide independent advice as design, construction methods and material specifications evolve.
When work starts on-site the developer/main contractor will assume responsibility for compliance and may need the services of specialist competent person(s) to ensure that any design, material changes and workmanship quality are fully compliant.
Kingspan’s robust standard details (RSD’s) have been developed to be installer friendly so that a high level of workmanship quality can be achieved combined with fast installation speed.
Design Specification & Build Quality Compliance
The materials to be installed and workmanship quality has to be inspected during construction to enable the competent person(s) to provide the required certificate or declaration following air pressurisation testing and thermographic inspection survey. Kingspan’s construction details have been designed to provide the quoted thermal insulation (U-value), minimal condensation risk (f-factor) and thermal bridge heat loss (Psi value (Y)) values as easily as possible under site conditions.
Thermographic Inspection
Part L2 requires that responsibility for achieving compliance to avoid excessive thermal bridging, rests with the person(s) carrying out the work. The person(s) responsible for achieving compliance should (if suitably qualified) provide a certificate or declaration that the provisions meet the requirement of Part L2, alternatively a competent person(s) may issue such a declaration.
Alternatively a thermographic inspection survey by competent person(s) should be carried to demonstrate that the insulation is reasonably continuous over the visible envelope of the building and that excessive thermal bridging is avoided.
Note: Building Control should be asked to confirm in advance who they consider is competent to complete the various declarations required before the completion certificate is issued.
Failure to achieve regulatory compliance will result in project handover delays, rectification costs and consequential losses.
Thermographic Inspection Survey Specification See lower for thermographic inspection specification document which can be incorporated into project tender and contract documents.
Air Permeability Testing
On buildings of any size, an air leakage test has to be carried out to provide a declaration from a competent person(s) that the test result demonstrates regulatory compliance either to Part L1 or L2 as appropriate.
Alternatively for buildings of less than 1000m² floor area a declaration that appropriate design and installation has been carried out to achieve conformity to specification for regulatory compliance.
Kingspan’s construction solutions and details have been designed to provide a barrier to air leakage which competent cladding contractors can be expected to install successfully on site.
Note: There is no requirement in Part J Building Standards Scotland for either air leakage testing or thermographic inspection.
Air Pressurisation Testing Specification
See lower for for air pressurisation testing specification document which can be incorporated into project tender and contract documents.
Project Specification & Maintenance Manual
Compliance with CDM Regulations will require that details of the cladding specification and maintenance recommendations are included in the Operation and Maintenance Manuals for the completed building. Part L2 recommends that the measured air permeability of the building is included in the building log-book, together with references to the O & M Manual.
Energy Usage Log Book
Part L2 requires that a log book be provided giving details of the installed building services plant and controls, their method of operation and maintenance, and other details that collectively enable energy consumption to be monitored and controlled. The thermal insulation values and airtightness of the building envelope are significant contributors to the overall energy efficiency performance of the building, therefore, these details should be included in the log book.
Thermographic Survey Specification
1. Thermographic Surveys
Carry out infra-red thermography inspections using a specialist consultant to demonstrate that the insulation of the building is reasonably continuous over the whole visible envelope, that there are no unintentional air leakage paths through the fabric and that insulation aspects of the works have been carried out in accordance with construction drawings.
2. Survey Method
Survey to be carried out as recommended in BS EN 13187 and CIBSE Technical Memoranda TM23:2000 Testing Buildings for Air Leakage.
3. Programme
The contractor should allow sufficient time in the programme to rectify any defects that become apparent in testing and retesting to demonstrate compliance prior to the completion date.
4. Quality Control and Supervision
The contractor shall be responsible for the site quality control to check that the sub-contractors and suppliers complete the works in accordance with the contract drawings and specifications – including any approved subcontractor’s drawings where applicable.
5. Access
The contractor should provide appropriate access agreed in advance with the specialist.
6. Conditions and Testing
The contractor should ensure that the test is carried out under appropriate conditions:
- The contractor should allow for heating the building to establish a temperature difference between inside and outside of at least 10°C during the test and at least 5°C for the preceding 24 hours
- All building surfaces to be inspected to be dry
- No precipitation (including mist and fog) immediately prior or during the survey
- Wind speeds during the survey must not exceed 10 m/s
7. Witnessing
Tests to witnessed by the contractor, the Contract Administrator (CA) and Building Inspector (if required). The contractor should liaise with all parties in advance to ensure their attendance.
8. Test Failure and Re-testing
Should the tests reveal defects in detailing or in the continuity or insulation or the contractor shall be responsible for undertaking the necessary investigation, allowing for inspection by the CA, remedial sealing works and further tests at his own cost until it can be demonstrated that the building complies with Clause 1.
9. Report and Certificate Provide a report illustrated with thermal images of any defects (including temperature calibration scale) of the results of the survey to the CA, Building Control, the employer and Planning Supervisor for inclusion in the Health and Safety File.
Airtightness Testing Specification
1. Introduction
The contractor should note that the building is to be constructed so that air infiltration and exfiltration through the external envelope is minimised. It has been detailed accordingly and the contractor should pay particular attention to this aspect during tendering, procurement, construction, commissioning and handover.
2. Air Permeability Standard
The building will be tested for air tightness before practical completion and must achieve the following minimum standard of air permeability to Part L2* of the Building Regulations for England and Wales:
- Not greater than 10m³/hr/m² * of building envelope at a maintained pressure difference of 50Pa.
*or clients specification.
3. Contractor’s Design
Achieving a high standard of air permeability depends fundamentally on standards of workmanship on site and, therefore, responsibility for achieving this standard rests with the Contractor.
4. Specialist Input
In order to achieve the above, the Contractor may wish to employ a specialist to provide a service that includes the following: Design Review in advance of procurement:
a) Comment in writing on the construction information prepared by the design team, identifying potential gaps or weaknesses in the detailing of the air barrier or potential buildability issues.
b) Confirm those parts of the building which will be considered outside the building envelope during testing.
c) Submit as mark-ups or in writing alternative proposals or modifications to design team information to enhance air tightness or improve buildability, provided always that they follow the design intent of the design team’s drawings.
d) Identify further details required from the design team in order to clarify continuity of the air barrier.
e) Advise the contractor on subcontract responsibility and sequencing to ensure completeness and continuity of the air barrier.
Construction phase:
a) Visit site at suitable times throughout construction to advise on proposed construction stages in advance, bringing particular watch points to the attention of the contractor’s and subcontractors’ staff.
b) Visit site to inspect the works at suitable times throughout construction, providing a short report on workmanship, activity sequencing, subcontract interfaces, site processes, materials or detailing that may affect the integrity of the air barrier. Visits should generally be timed to coincide with visits by the CA.
Reports to be submitted to the contractor and the CA.
c) Advise the contractor on temporary air sealing and preparation works for testing.
Testing:
a) Carry out a fan pressurisation test or tests (only in the event of partial handover) in order to prove compliance with the Specification in accordance with CIBSE Technical Memorandum TM23 – Testing Buildings for Air Leakage. The maximum leakage rate specified refers to the envelope area including solid ground floors. The external envelope area shall be accurately calculated by the testing organisation from scaled drawings provided by the contractor prior to the test.
b) The tests must be carried out in the presence of the CA and Building Inspector (if required) and allow for sufficient time under test to investigate any problems that come to light while the pressure difference is applied.
c) In the event of a failure, provide appropriate smoke visualisation devices and/ or thermographic survey equipment to identify air leakage paths.
d) Re-test as necessary to demonstrate compliance.
e) Provide a written test report in advance of practical completion to the contractor, employer and CA certifying compliance with the specification.
5. Specialist Consultants
The choice of specialist consultant must be approved by the CA and should be a member of the Air Tightness Test and Measurement Association (ATTMA) and/or UKAS Accredited to BS 17025.
ATTMA member familiar with Kingspan Products include:
Contractor’s Duties
6.1 Integrity, Continuity and Durability of the Air Barrier System
The contractor is responsible for the integrity, continuity and durability of the air barrier system which must be addressed by all relevant components and at all relevant junctions, penetrations or openings.
6.2 Coordination and Allocation of Responsibility
The contractor shall be responsible for coordinating the works to achieve the specified air tightness performance and for specifying which subcontractor or supplier of each part of the building is responsible for the air tightness of the junction between their work and another’s.
6.3 Performance of Components The contractor shall be responsible for ensuring that each supplier of each part of the building is responsible for achieving the air infiltration performance of that part of the work.
6.4 Quality Control and Supervision
The contractor shall be responsible for the site quality control to check that the sub-contractors and suppliers will achieve the air tightness performance requirements.
6.5 Programme
The contractor should allow sufficient time in the programme to rectify any defects that become apparent in testing and retesting to demonstrate compliance prior to the completion date.
6.6 Approval of Variations
All sealing works required to ensure continuity of the air barrier system must be carried out in accordance with the design details and with materials approved by the employer’s representative.
Any variation to the works involving air barrier continuity must be approved by the employer’s representative.
6.7 Preparatory Work and Temporary Sealing for Testing
Allow for preparatory works and temporary sealing (and removal on completion) of free openings, flues, air supply openings and ventilation system inlets and outlets as described in CIBSE Technical Memorandum TM23 – Testing Buildings for Air Leakage.
6.8 Partial Handover/Phased Construction
Carry out additional testing to suit phased construction or handover. Allow for temporary sealing/ enhancement as required for partial testing, for example, in connection with partial handover, noting that materials and detailing specified for internal walls may require enhancement in order to provide an air tight barrier for such testing.
6.9 Test Failure and Re-testing
Should the building fail to comply with the specified maximum air leakage, the contractor shall be responsible for undertaking the necessary air leakage identification, remedial sealing works and further fan pressurisation tests at their own cost until the specification is achieved and demonstrated to the employer’s representative.