There is an important difference. "Should" implies necessity or expression of an opinion. The building materials need to be stored there at some point in the future and there may be bad consequences if they are not. "Will" implies that in the future the building materials are going to be stored there as part of a plan.

What is the difference between will and should?

The word 'should be' is used to express an opinion or advice in a sentence by a person. The word 'will be' is used to express that a particular statement will surely happen in the future. The word 'should be' is usually used in a sentence having a past or future tense.

Would and will Difference examples?

Many English learners get will and would confused because they're used in very similar situations. But they're not the same. The main difference between will and would is that will is used for real possibilities while would is used for imagined situations in the future.