How to use the standard CSA A123.21 for the renovation of a roofing low slope (flat roof)? As mentioned in previous articles addressing the legalization, specification, and the application of the standard CSA A123.21, it is essential to know the constraints and limitations of the standard to use it.
Wath we heard from « commercial's sales »
Most of the roofing industry stakeholders agree the standard of resistance to the CSA A123.21 wind as being the basic reference to the Canada for new roofing projects. For renovation projects, whether in the form of partial rehabilitation or surface replacement, the situation is no longer the same. The existing Assembly should be considered
However, as the standard is relatively recent, many manufacturers see an interesting source of marketing for their assemblies. In referring some relatively incomplete data to the application of the methods of assemblies, they mystify users. Many are even mentioned that the results of assemblies can be applied on any type of roof and substrates, whatever they are.
Wath should we understand ?
To understand the ins and outs of the standard, you should know that there are three types of assemblies that are named: MARS, PARS and AARS.
MARS assemblies
March is an acronym for "Mechanically Attached Roofing System" which is translated as "mechanical attached Roofing System. This Assembly means that the membrane is mechanically attached following the recommendations of the systems tested by the manufacturers.
PARS assemblies
PARS is an acronym for "Partly Adhered Roofing System" which translates as "roofing system partially signed. This type of Assembly means that some elements of the Assembly are attached mechanically and that others are adhered.
AARS assemblies
AARS is the acronym for "Adhesive Adhered Roofing System" which is translated as "Roofing Systems element were adhered" with adhesive. This Assembly requires that all elements of the Assembly are attached to each other by adhesive ribbons or fully adhered.
For each of these assemblies, the forces applied to the various elements are different. They are either under structural or pneumatic effect or a mixture of the two as shown on page 22 of the standard CSA A123.21. See the image below.
How to integrate the standard CSA A123.21 to your project
For a new design of roof, no constraint on the application of the standard is significantly. However, for the replacement of full or partial roof work some elements must be considered to meet the requirements of the national Code of the building of Canada, 2015 edition.
As a first step, you need to know whether your building is insured by FM Global. In case it is not, the CSA A123.21 standard must be applied considering of the different elements and constraints from each sector roofing repairs.
Laboratoiries tests results
All manufacturers carry out resistance to their assemblies in laboratory tests. Basically passes on steel, concrete or new wood with specific ranks with their own resistance properties are used to perform these tests. The results form the basic data.
Each project must meet these basic data, mainly when mechanical fasteners are used. For example, if a system has achieved a result X with a resistance of 300 lbs fastener during the test in the laboratory, the professional must make sure to know the resistance of the fastener specified on the quote function to obtain this resistance of 300 Ibs to the minimum in the field project itself.
Thus, MARS and PARS methods may well meet the standard of the CSA A123.21 wind resistance, with first condition, knowing minimum loads and resistances to meet. To do this, normative test 'In Situ' should be done during validation of the systems to keep in place. These standardized tests are for ANSI/SPRI FX - 1 anchors and for cases of repairs in grip standard ANSI/SPRI AI - 1 can provide the basic information necessary for the application of a system of AARS.
Central Roof Reference
Independent and neutral, Central Roof Reference informs you on the various aspects of the standard CSA A123.21 and its application for your roofing projects. For more information, please contact us. Please conact us.
Michel Desgranges, T.Sc.A.
