The most important thing to check the safety of a bunk bed when buying it from an individual is to be sure to see the bunk bed fully assembled. This gives you the opportunity to examine the strength, quality and durability of the bed.
According to Bunkbeds.net, bunk beds should be fitted with guardrails. If the bunk beds do not come with these, purchase them separately. Checking all hardware and fittings to make sure they are stable is a good way to tell what sort of shape the frame is in. If there is any sort of weakness in the frame, it is not safe for children to climb on daily. The bunk bed should come equipped with the correct designated ladder that was made specifically for the model, as an improper ladder can slip out of place and cause injury.
Any pieces of wood that may show signs of old age, such as splintering and cracking, should be avoided. If it is a metal frame, checking for signs of erosion, such as rust, can indicate an inadequate frame. Many people build their own bunk beds, and it is essential to look for good quality wood and hardware for the most sturdy and durable frame possible when purchasing from the owner.