BOMA 96 does not address this kind of split-building scenario. BOMA allows for a single Floor Common Area allocation per floor and likewise, there is only one Building Common Area per building. There are a couple of ways to deal with this:

1. Calculate strictly to BOMA 96 and allow your tenants to proportionately share all common areas normally regardless of who specifically uses what. In the case of your building, this seems reasonable as the two halves of the building are more or less mirrors of each other. This should create a fairly equitable distribution of Floor Common Area over the floor plate. Building Common Area will be allocated over all tenants either way.

2. We sometimes introduce a 3rd common area type that we call Private Common Area. We allocate Private Common Area to 2 or more tenants who are sharing the amenity exclusively. We usually gross-up Private Common Area by Floor Common and Building Common before allocating it to tenants. This creates a rather complicated area chart, but it works.

3. Treat the building as two distinct buildings and produce 2 BOMA charts, allowing each it's own common area calculations. You could then use a simple calculation to factor in the shared electrical and heating rooms. We would usually call this Complex Common Area or Campus Common Area.

It is important to note that options 2 and 3 are not specifically supported by BOMA, so you are stepping outside the framework. This practice is usually referred to as Modified BOMA. We cannot comment on whether this is appropriate for your leasing scenario, however we do believe that as long as modifications are well documented and that all leasing parties agree upon their implementation, that Modified BOMA can be a good solution to complicated leasing scenarios.