Sealed aluminium blind rivets are used to rivet the panels and extruded aluminium profiles together. Typically, 4.8mm rivets are used. Make sure that they are sealed rivets. Although its unlikely that standard rivets would allow water penetration, its best to not take any chances. One very useful tool to invest in is a riveting gun that attaches to a normal cordless drill. This will save a lot of frustration and time!