This question may sound comical, but believe it or not…I get asked this quite often. Granted, it is usually not this generic. The reason this question may sound comical is because as one could imagine, there are probably a few million (at least) ways to answer this because of all the variables that go into a building of any typology. Here are some of the things that a potential client (owner) should consider in terms of building costs:
The building proper:
Some would refer to this as the “sticks and bricks” or the “general structure” of the building. The building proper includes the “systems” of a building – which are the bare necessities of a building…without them there is no building at all.
Wood trusses being placed on a “block” home. Click the image to view the completed home…
Finish level (interior):
This term refers to how the interior spaces are literally finished. Some examples of interior finish would be:
- flooring: laminate flooring vs. carpet vs. exotic hardwood flooring vs. imported marble flooring
- fixtures: generic faucets bought from Home Depot vs. Hansgrohe faucets vs. Altmans faucets
- “skin” materials: using textured gypsum board vs. smooth gypsum board vs. plaster vs. tile vs. metal vs. wood planks vs. etc…
- casework: no molding vs. light molding vs. heavy molding
Finish level (exterior):
This term refers to how the exterior of the building is literally finished. Some examples of exterior finish would be:
- cladding: using stucco vs. Hardie board vs. brick vs. metal panels vs. California redwood
- windows: vinyl vs. aluminum vs. wood – single hung vs. fixed vs. casements
- roofing: shingles vs. slate vs. concrete tile vs. metal vs. flat roof
Structural complexity:
One should always keep in mind that when it comes to buildings, the closer to a box the cheaper it will be to build. The further from the box the more money it will cost; it is just that simple. Then it pretty much falls into the “common sense” category: orthogonal (lines or walls at right angles) are cheaper than angles which are both cheaper than curves. As some designs get funky, we have to perform what we call “structural gymnastics”…meaning we have to perform incredible feats with or posts and beams to achieve the desired affect. This shouldn’t scare you off, but once again, I think 10/10 people would agree (that weren’t architects or engineers of any kind) that a circular building would cost more than a rectangular one.
General building construction type (in order from least to most expensive-generally speaking as this is dependent upon the contractor’s crews, availability of materials, gas prices, etc.):
- wood (or “frame” or “stick-built” or “stick-frame”) building: now within this bracket would be what size frame are we talking about? The thicker the lumber the more expensive. Most of the time when people refer to a stick-frame building they are referring to a smaller building constructed of 2×4 studs which act as the structure for the building. The benefit to larger members is that you have more room for insulation and sound absorption.
- CMU (mostly referred to as a “block”) building: made of CMU, or Concrete Masonry Units…most people would refer to these little guys as “cinder blocks”. It is important
to understand that a block building does not mean the entire building is made of block, only the exterior walls. The interior walls would usually be made of wood studs in a residential project (small scale) or metal studs in larger projects. - metal building: with this building type, like with frame construction, the studs (metal in this case) would be used for exterior and interior walls.
- cast concrete: formed and poured structural concrete walls.
- precast concrete panels (or prefabricated panels of any kind): these are pre-engineered slabs of concrete (or another material) that are gently and very systematically placed into the building. This requires great planning and precision. In some cases this system is very beneficial because although the materials can be costly and the labor slightly more expensive, the value comes in terms of time. Sometimes pre-manufactured buildings can go up in a fraction of the time it would take to build a more traditionally built building.
to understand that a block building does not mean the entire building is made of block, only the exterior walls. The interior walls would usually be made of wood studs in a residential project (small scale) or metal studs in larger projects.Equipment:
This can mean a lot of things but generally when I hear this term with regards to a building 
I am thinking in terms of large pieces of equipment that will go into the building such as:
- conveying systems (elevators, dumbwaiters, etc.)
- mechanical/HVAC equipment including ductwork (is it architectural grade, meaning it is meant to be seen and shown off? or is it going to be buried in a plenum?)
- specialized equipment (is there a 5,000 lb. whatever machine going in on the second level? are there twenty of these machines? thousands of these machines?)
Appliances:
How many? What type? Electric or gas?
Now obviously this is not meant to be a comprehensive list of items that go into a building, but they are the biggies that I can rattle off effortlessly. Even within these seven categories one can see the myriad of decisions that need to be made either based on price, desired aesthetic, site conditions, or a combination of these factors.