Why are roof structure inspections necessary?
vc_separator no-text align_left wpb_content_element vc_el_width_5075pxstyle="border-style:;border-color:#fc5f16;border-width: 4px;"12#fc5f16It is a statutory requirement to comply with all the provisions of both the Building Standards Act Section 14(2A) and the National Building Regulations (Regulation A19) in order to obtain an Occupation Certificate from the Local Authority.
Through the proliferation of bad practices in the Roof Erecting Industry over many years, we have now witnessed an increase in this disturbing trend of Roof Structure failures.
Case studies, worldwide have confirmed that a lack of compliance with recommended installation procedures were the common cause of most of these failures and collapses.
We know that roof structures are made up of individual wood framing members that are connected with specially designed metal plates. These are amazingly strong once they are installed & braced as a system, but, they are surprisingly fragile as individual trusses. They have very little lateral strength or resistance to lateral forces.
The successful Erection of Timber Structures is possible through compliance with the National Building Regulations Requirements as contained in the SANS 102453 & SANS 10400(L) codes of Practice.
The role of the Inspector is therefor to check that these guidelines are carefully followed.
Pre-fabricated trusses that are handled with care, erected and installed properly, have proven their value in the industry. Unfortunately, their value is sometimes questioned when failure or collapse occur.
It is a fact that many roof structures fail during the construction phase while others take years for an incident to occur.
Incorrect loading or overloading during construction, like high winds or mishandling of trusses during erection, utilizing weak members or bad joint connections, damaged, broken or improperly repaired trusses, or installing unacceptable or unauthorized design changes on site.
These are some of the main reasons why trusses fail or collapse.
Then there is the problem of 3rd party interference after these structures were erected.
These mainly involve adding additional services like air conditioning systems, water system and electrical systems to the structures, which they were not designed for.
There is an International Residential Code of 2006 that states: “Truss members shall not be cut, notched, drilled, spliced or otherwise altered in any way without the approval of a registered Professional Engineer”.
How often have we seen these “remedies” done without any consultation, at the Erectors own discretion?
Structures with proper design and construction of bracing systems are essential in reducing and / or eliminating timber structure failures.
As I have mentioned before, the fate of these structures are to a large extent, determined right at the beginning stages of construction/erection.