There is a difference between rentable square footage and usable square footage and in some locations that is something to consider carefully. Virtually all floorplates (incremental slices of the building) have space allocated to common areas like washrooms, elevator cores and the like. That square footage is divided over the respective footage of each tenant on the floor and becomes part of the rent. That seems perfectly reasonable. Where a problem may arise is in the case of an unusually shaped building or an ordinary structure with an excessively small column grid.
Furniture is essentially a series of (more or less) right angles; so are filing cabinets, appliances and doors. Populating irregular space with regular objects, or space with a high number of floor obstacles, increases the likelihood that this fundamental mismatch will result in square footage that serves no useful purpose. A good interior designer can mitigate much of the problem by allocating space and locating amenities in a way that uses irregular space to best advantage.
The most important consideration in selecting an interior designer, assuming comparable skill and experience, is finding someone with whom you can work closely. That is not necessarily the person you like the most nor even the one with the best sales pitch, though it might be. Rather, it's the person who shares your values and understands the objectives of the project.
Planning new space is an intensive process. It requires considerable thought and there are literally thousands of decisions, large and small. More than any other member of the project team, the interior designer provides timely and unbiased advice to keep the project on track. There will be many meetings and discussions, and that time will more productive if you like the people with whom you are working.HOME FAQ's