A good roof shelters the hive box from the Sun and rain. If a colony gets too hot it can die/ cook. If water runs down the side of the box it can sit in any gaps or joins and over time rot the wood, or even worse flood the colony.
A well made box will have no gaps and nicely fitting joins but water or moisture can get in to anything over time. Wood will continue to shrink and expand, and with time and water can get in between these gaps.
we have a few Roof options.
Colorbond roofs fitted correctly can provide SOME protection..but they are an entry level roof, and you still need to place your hive in the shade
Our Celuka roofs offer a wide large footprint. keeping water off your hive. it cant run down the sides, and is a very insulating product, we use the celuka roofs on our hives, they are positioned NORTH facing in the full sun, all day with this roof fitted there is no issue. This is the best option for roofs in our opinion as it wont warp, crack, rot or take up moisture, and its light weight.