Q. We are considering building a new facility and installing a false or secondary ceiling under our roof. Is the extra cost justified as a means to decrease overall maintenance costs?
A. What you are referring to is called “interstitial space.” As you stated, it is a load-bearing, secondary roof located 6-8 feet beneath your existing roof.
This interstitial space serves several purposes. It allows many maintenance operations to be conducted simultaneously with production runs without compromising food safety. It also allows some equipment to be located out of the production environment (which could increase its useful life and decrease associated indirect costs). Also, by relocating equipment above the normal “wet line” of sanitation, fewer equipment failures due to the introduction of water will occur. The cost of cleaning the plant will be lower, thanks to less conduit, pipes and ductwork along the walls and ceilings. It definitely creates a cleaner building envelope for efficient production operations.
Whether it makes sense to incorporate interstitial space into your plans depends on several factors: the impact on maintenance operations and sanitation procedures and, most importantly, the impact on your ability to produce a product free of foreign contamination.
If you have a “captive” system in which products are transported through pipes from one process to another and without direct exposure to the environment, a large investment in interstitial space makes little sense. However, if you have a lot of equipment that can be located in the interstitial space and can be serviced on straight time without any interruption to production, the additional capital cost may be justified.
If product transport from one process step to another consists of open conveying and exposure to the environment, an interstitial space will offer enhanced protection. Drop downs for electric service and other utilities almost eliminate dust and dirt harborage from overhead pipes and other horizontal surfaces. Cost reductions for maintenance also should be calculated.
Those savings need to be balanced against the added cost. Although not as high as installing the main roof, a secondary roof can mean as much as a 70 percent premium over an external roof alone.
Capital spending decisions are a team sport that requires weighing both cost and benefit. This type of expenditure cannot be based solely upon maintenance savings. Get all stakeholders involved in the decision-making process, not just the maintenance team.