The exterior walls of most modern facilities are generally made from bricks or concrete. Some facilities have single walls and others have double walls with a cavity in between. Given the right circumstances, brick and concrete can both be porous and allows the passage of moisture from the outside, where humidity levels are generally higher, into the storage areas.
So, the walls should be designed and built in such a way as to minimize the potential for external environmental conditions to influence the conditions we are maintaining in our storage areas. Particular attention should be given to ensuring that all archival storage areas are well insulated and sealed. Sealed vapor barriers between the walls, or the inclusion of insulation tightly fitted between wall studs and frames, or the use of sandwich panels (similar to materials used in cool rooms) is suggested.
All wall that surround record storage areas should be fire rated. The numbers are in minutes and, in order, we refer to an item’s :
a)Structural adequacy- the item will not collapse in that time
b)Integrity-the item will not fail in that time such as the fire will not burn through.
c)Insulation-the ability of the item to withstand heat, both conducted and radiant.
Fire rating for walls and doors have not, however, been standardized. British standard 5454-2000 Storage and exhibition of archival documents recommend a four-hour rating. ISO 11799-2003, information and documentation storage requirements for archive and library materials, recommend two hour.