Raising the Bar on Pedestal Set Applications
Pedestal applications involve suspending segmental concrete units over the roofing structure using plastic pedestals or polystyrene blocks. The concrete units protect the roofing materials from direct contact by foot traffic or equipment, shelter the roofing materials from severe climatic conditions, can be easily removed when access is required for repairs or maintenance to the roofing system, and are heavy enough (in most cases) to prevent shifting or uplift from high winds.
In an attempt to raise the bar on pedestal set applications (i.e. prevent product failures, which could cause personal injury) Oaks Landscape Products staff worked with the Concrete Masonry and Hardscape Association (CMHA) and the Interlocking Concrete Pavement Institute Foundation (ICIPIF) to introduce four initiatives:
- Introduction of a product standard for pedestal products, being 2000-pound centre-point loading. To put this into context, this is analogous to rooftop or patio common space applications where there may be entertainment events being held (i.e. a stage is set up), or where exercise areas are located. The Ontario Building Code requires a minimum specified concentrated load of 9 kN (918 kg [2,020 lb]) in these settings.
- Development of testing protocols for the pedestal units so that all producers across North America can easily and economically confirm compliance. Ultimately, the testing of full size specimens (24”x24”) is encouraged, but there are options to test reduced-sized samples saw-cut from full-sized slabs. The latter option was added as the majority of independent testing labs do not have the ability to test full-sized units.
- Addition of the above to CSA A231, Precast Concrete Paving Slabs and Pavers. This work is ongoing, as it is expected to be completed by the end of 2024. By adding the product standards and testing protocols to the CSA, they become the standard for use in Canada.
- Worked on the creation of a manual, Designing Concrete Paving Slab Rooftops for Wind Effects. As high winds pass over the rooftop, complex conditions can occur that create a pressure gradient between the top and bottom of pedestal supported products. If the pressure gradient is sufficient, the paver units can be dislodged, or under extreme conditions even thrown off the rooftop. The manual provides a checklist of things to consider, and a sample set of calculations based on National Building Code of Canada criteria.
Oaks also introduced a 600mmx600mm addition to its Molina 60mm product line specifically for pedestal set applications. The unit has been proven to conform to the proposed standards.