MAIN CHANGES TO THE TECHNICAL MANUAL
Section 1 Ground Conditions:
- The guidance on Ground Conditions has been updated to make it easier to understand. We have produced a new easier to use flow chart and introduced guidance for a basic ground investigation which is required where the phase one site investigation does not flag any hazards.
- Design 1 of the Functional Requirements now states that all site investigations must be dated within 5 years of construction starting on site.
Section 2 Basements:
- Design 1 of the Functional Requirements has been updated to now state 'Elements that are integral to the waterproofing structure of basements including foundations, walls and floors shall be designed by an Engineer to support vertical loading, resist horizontal loading and surcharges including the influence of nearby trees and topography'.
Section 3 Foundations:
- We have combined sub section 3.1 (Foundations - Mass Fill) and sub section 3.2 (Foundations - Strip) from the previous Technical Manual into one new sub section called 'Foundations – Mass Fill and Strip'.
- New guidance on vibratory ground improvement is provided to take into account latest industry practices
- Our 'Foundations - Trees and Clay' section has the following changes:
- The 'Changes in level' guidance has been updated to make it easier to understand
- We have a new table which outlines where heave precaution should be used in varying situations.
- New guidance provided for where rafts are proposed in shrinkable/expandable soil within the influence of trees.
- Updated guidance on strip and mass fill foundations in non-shrinkable soils overlying shrinkable soils.
- The guidance within the section as a whole has been consolidated
- We have introduced new guidance on flexible and rigid retaining walls
- We have new guidance on helical (screw) piles
Section 4 Ground Floors:
- Updated guidance on stepped party walls is provided
Section 6 External Walls:
- The limitations of the Functional Requirements has been updated to now clarify: Means of escape, passive and active systems are not covered by the warranty.
- Design 1 of the Functional Requirements has been updated to now state that external walls shall be designed and constructed so that they meet the requirements of the Building Regulations
- The table for 'Suitable cavity wall construction depending on exposure, for use with full fill cavity insulation' has been updated based on latest industry practices
- We have updated our guidance on lateral restraint to make it clearer
- Updated requirements for breather membranes in the timber frame and light gauge steel frame sections
- We have clearer guidance on what we categorise as open and closed panel timber frame systems
- The guidance for timber frame differential movement has been updated to make it simpler to understand
- New guidance on gable spandrel panels is provided
- New guidance on using light gauge steel frame construction at low level is now provided
- Our testing requirements for curtain walling systems has been updated
- A new 'Provision of information' is added to the different cladding types in sub section 6.5
- New requirements for natural stone masonry are provided
Section 8 External Windows and Doors:
- We have retitled our section on stacked windows to 'Vertically Stacked Coupled Window Assemblies' to better reflect the type of window system we are now referring to within the guidance. This includes updated guidance to provide more information on coupling joints, testing requirements, structural integrity, thermal bridging, window sills, accommodating movement and a statement for vertically stacked coupled window assemblies over 5 storeys.
- New requirements for water tightness provided for glazing systems in developments over 6 storeys.
Section 9 Stairs:
- We have new guidance on glazed guarding
Section 11 Roofs:
- The limitations of the Functional Requirements has been updated to now state 'Means of escape, passive and active systems are not covered by the warranty'
- We have combined sub sections 11.1 (Roofs – Pitched - Pre-formed Truss) and 11.2 (Roofs – Pitched - Traditional Cut) from the previous Technical Manual and condensed them into one new sub section called 'Roofs - Pitched Roof Structures'
- Our guidance for concrete interlocking tiles, plain tiles and slates has also been condensed into one sub section called 'Roofs - Pitched Roof Coverings (Tiles and Slates)'
- We have introduced a new sub section titled 'Panelised Roof Cassettes'.
- Additional guidance is provided for where LR underlays are used on a fully supported material
- A new table is included to provide guidance on gauge, headlap and permissible pitch for different pitched roof covering types
- Guidance has been added for additional testing of flat roofs where a test fails
- Guidance on the vegetation free zone for green roofs has been updated to provide further details to bring it in line with latest industry practices
- The 'Provision of Information' for pre-formed trusses and traditional cut roofs now includes:
- Third party product approval certificate for the roof underlay
- Details of the ventilation strategy for the pitched roof in line with the guidance provided in this section and/or BS 55250
Section 19 Garages:
- New guidance added for 'Services within a garage'
- New guidance provided for garage floors. We now recommend garage floors should be laid to a fall and have a step where they’re integral to the house.
Appendix C:
- In the Functional Requirements, Design 1 from our previous Technical Manual has been removed
- New guidance is provided on the required supporting information for cavity trays and DPCs
- New guidance provided for steelwork protection categories in varying environments
- Guidance added for proprietary products and systems in place of a traditional construction method
- We now have guidance on what we require for products that do not have a third party product conformity certificate
- Our list for what we expect to see in third party certificate has been updated
- Our service life table has been updated to include thermal insulation and breather membranes in vertically framed external walls
Read more articles on InSite and sign up to receive our blog round-up.
Every care was taken to ensure the information in this article was correct at the time of publication (March 2024). Guidance provided does not replace the reader’s professional judgement and any construction project should comply with the relevant Building Regulations or applicable technical standards. For the most up to date Premier Guarantee technical guidance please refer to your Risk Management Surveyor and the latest version of the Premier Guarantee Technical Manual.
