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 //