In the November Blog, we talked about many of the advantages of multi-story buildings. We looked at factors ranging from shorter travel distances to visual messages a multi-story building can send. For this article, we decided to view multi-story construction through a different lens and explore the reasons our clients choose to avoid multi-story buildings more than 90% of the time.
Unproductive Building Area
When comparing multi-story to single story buildings, one distinct disadvantage is the increased amount of unproductive building area. What does that mean, you might ask? Well, let’s start with the big one, and this is where most of our conversations end.
Multiple stories mean we must design building areas and systems for moving people between floors, specifically, stairs and elevators. In addition to moving people between floors, we also have to allot space to run ducts, plumbing and conduit between floors. Why is this a so significant? Well, put simply, you are spending money on something other than usable space.
This is the floor plan for the project we mentioned last month in Central Texas:
This building is pretty small and uses about 6.3% of the floor area to move people and utilities between floors. Most things in life don’t scale proportionally, but that roughly 6% of the footprint doesn’t change even with a considerably larger building.
This is a two story building from a larger project also located in Central Texas.
The area required to move people and systems between floors in this larger building is right at 6% as well. But there are ways to save a little bit of space and a little bit of money. Building some of the stairs on the exterior of the building, like we ended up doing on both of the projects above will help economize interior space. But, even with that, you’re still going to pay to build the stairs.
Safety and Surveillance
In multi-story buildings, stairwells and elevators add another area that must be monitored. You can use an open stairwell for the majority of your movement, but as far as the code is concerned that stairwell doesn’t exist. Building code requires an enclosed, fire protected staircases to exit the building.
Additions to buildings with multiple stories are considerably more difficult than adding on to single story buildings. With careful planning, it can be done, but it is more difficult. In the project above, we planned for a future addition, making the actual construction of the addition a lot easier. We aligned the two corridors and built the stairs as inexpensively as we could, and they were built in such a way that they could be removed and reused later. If desired, the owners can build an addition, extend it to the outer building limits of the property and use the stairs again.
Fire Suppression Systems and Municipal Water Pressure
This is an issue that causes more consternation than one might expect, especially in Small Town, Texas. Modern building codes push hard toward the inclusion of fire suppression systems, especially in large buildings and especially in educational facilities. In a lot of smaller and rural towns, the water utility simply cannot provide enough water pressure to properly supply a second floor fire suppression system. There’s even a law in Texas that requires water utilities to provide sufficient water pressure for second story sprinkler systems, but it isn’t enforced. To build up enough pressure you would have to add a tank to gravity feed the lines or add a pump. Either way, if your water provider doesn’t have enough water pressure that means more cost for you.
It Won’t Save You Money
Finally, with all other things being equal, multi-story buildings won’t save money. If we look at the usable area of a single floor building vs. the usable area of a multistory building, we will find that there is almost no difference in building costs. Actually, It costs just about as much to build the floor area of the second floor as it does to build the floor area on the ground floor. To add to that, when you factor in stairs and elevators, you end up spending more money per usable area with a two-story building.
Building multiple stories might be the right decision for your project and your community. You might make that decision because you are faced with a landlocked sight or the size might not be adequate to fit everything you need in one story. You might just want to send a certain message with your building or to simply cut down on the travel distance between classes for your students. However, outside of these considerations, the advantages of building a multi-story facility quickly evaporate. The hard reality is that the added costs for elevators, staircases and utility chases will increase your bottom line by 5 to 8%. When all these factors are taken into consideration, the question you must ask is “What is right for my community?” And with proper planning and research, and possibly the consultation of an Architect, you will arrive at an answer that will fit within your budget and address your community’s needs.