Between 2003 and 2009 two rooms that served as tritium laboratory at SCK•CEN and its ventilation system were decommissioned. Initially, the decommissioning strategy was to free release as much materials as possible. However, due to the imposed free release limit this was very labour intensive. Timing restrictions forced us to use a different strategy for the ventilation system. Most of the steel was disposed of to a nuclear melting facility. As a result there was a significant decrease in the required man labour. For the second laboratory room a similar strategy as for the ventilation was used: contaminated steel was disposed of to a nuclear melting facility and other materials that could not be easily decontaminated were disposed of as nuclear waste. At the expense of extra waste generation compared to the first laboratory the decommissioning was done using merely one third of the man hours. Comparison of the used strategies indicated opportunities for cost optimization. Even in absence of time constraints it is best to foresee a safe disposal of metals to a nuclear melting facility, whilst it is worth to invest in the labour intensive decontamination of the other materials to free release them.