FEATURES
REGULATIONS RELATED TO TIMBER TRUSSES
As an alternative source of power, many people consider the installation of solar photovoltaic( PV) panels, which are usually installed on the roofs. There are certain factors that must be considered before installing PV panels.
One of the most important things is the timber trusses which are used to construct the roof. According to the Institute for Timber Construction South Africa( ITC-SA), there are certain requirements and specifications pertaining to timber trusses. Such requirements are compulsory as they must comply the National Building Regulations and the Building Standards Act. The requirements are put in place to ensure that the roofing structure of a home is built safely and successfully. Timber roof trusses must be manufactured in accordance with the South African National Standards( SANS) regulations.
The regulations consist of three essential components:
• SANS 10160 for loadings and procedures to be adopted in the design of buildings.
• SANS 10163 which relates to the structural use of timber.
• SANS 10243 which deals with the manufacture and erection of timber trusses. One of the regulations of SANS 10243 states that timber used for trusses must be stamped with the design structural grade value. In addition, the timber must have a visible certification logo.
When proceeding to erect the roof, it is important that the person doing so is reliable and has the necessary skills and knowledge to do it.
Prior to having the solar panels installed, the roof trusses must be assessed to determine whether they could be able to carry the weight of the PV panels or not. This process involves assessing the condition and construction of the roof trusses, calculating the weight impact of the solar modules and support structures, and taking into account the potential impact of different weather conditions.
Solar panels can weigh about 9 to 22kg, the actual weight of a solar panel will be determined by the size of the house. The panels are typically distributed evenly across a roof along with the racking systems that support them. The size and number of solar panels required depends on the size of the house. A bigger house would obviously need numerous big panels compared to a smaller house.
SOLAR PANELS ON THATCH ROOFS
Solar panel installations are not only limited to tiled roofs as homes with thatched roofs can also have solar panels installed, although this is not very common. Jacques Cronje, owner of Jacques Cronje Timber Design, worked on a project to install solar panels on a thatched roof house in Mozambique. Explaining what it was like to work on the project, Cronje says that it is not the best idea to place the solar panels directly onto to the thatched roof.
A solar panel installation on a thatched roof house. Image: Pixabay
“ The PV solar panels need to keep cool so they must not be placed directly onto the thatch roof,” he says. Cronje adds that solar installations on thatched roofs are not common at all.“ This was the first time I ever installed solar panels on a thatched roof.”
In addition, he explains that thatch needs to be able to dry out after getting wet from rain. Airspace is therefore an important consideration regarding solar installations on a thatched roof. Cronje recommends dedicating a section of the roof for the solar panels.
“ For the project we did in Mozambique, the panels are placed on corrugated roof sheeting, with an airspace between the PV panels and the corrugated roof sheets. The thatch was brought right up against it so that the panels appear integrated with the roof covering rather than looking like an add-on. Off course, those sections of the roof need to have conventional ceilings on the inside,” he says.
If a home owner is planning on installing solar panels on an older house, they must ascertain if their roof has been designed to carry the weight of the panels. It is advisable to approach a professional to do a thorough investigation which include calculations and measurements. Depending on the outcome of the investigation, certain alterations may need to be performed on the roofing trusses to ensure that it will be able to carry solar panels. If the roof needs maintenance, it is best to do the maintenance prior to having the panels installed. This is because solar panels generally have warranties, therefore sorting any maintenance problems out prior to having panels installed saves a lot of time and money such as having the panels disconnected during any roof renovations.
Installing solar PV panels is just one of the ways to survive the winter season. Taking the timber trusses into consideration is essential because the panels have a direct effect on the trusses. The panels must be installed correctly and all regulations adhered to.
Sources: ITC-SA Civic Solar Department of Energy Roof inspection Timber Design
42 JUNE / JULY 2017 //