I have been ’plugged-in’ to cost estimating ever since an early successful experience. So I never shy away from the issue of how much something costs. Eventually I noticed that this tendency of mine was creating these little mini projects as I chased down client requests for the costs of things - doing actual estimates. Finally I got my head out of the sand and looked around. What I saw was that the cheapest way to do things is what you see all around you.
Nature encourages economy and so does human nature.
Rather than charge off into a study of costs, I realized I could usually answer the question by just pointing out what everyone else was doing about the issue in question. If it was reasonable to use the requested 'ABC' material, you would see lots of 'ABC' around you.
Here are a few of the snipe hunts that I went on.
Why not leave the structure exposed instead of installing an acoustic ceiling? It seems reasonable that ’saving’ the cost of a ceiling would be cheaper. If a truly ’let it all hang out’ warehouse theme is what you are after, it is. However as soon as you try to dress it up with painting or organized conduit all the savings disappear.
Is it less expensive to expand a building up? Expanding up is only cheaper when horizontal isn't possible. A few of the extra costs: re-framing for stair penetrations; beefing up the roof to floor load standards; re-locating roof mounted equipment, flues, and vents; and special water tightness provisions during construction. Here's a post on this topic.
Shingles or flat roof? $2/SF vs $5/SF respectively. However sometimes codes or large spans make shingled roofs unworkable.
Gutters or roof drains? Gutters are always cheaper, but not by a lot if you can get your roof to slope to the roof drains by sloping the roof framing.
Isn't two stories cheaper than one story? One story is always cheaper, except perhaps in houses. I had to work this one out with an analysis of the math. Here is another take on the issue.
Wouldn't it be cheaper to use fire-rated construction instead of sprinklers? Sprinklers are always cheaper unless you have a water supply problem or a small building (<6,000 SF).
Aren't drywall ceilings less expensive than acoustic ceilings? Drywall ceiling are cheaper in houses and acoustic ceilings are cheaper in commercial buildings. There is no framing system required in houses to support the drywall.
Is it expensive to have glass office walls? Contrary to what you see on television where glass walls are ubiquitous, yes, it is lots more expensive to have glass walls, at least three times as expensive.
Is it expensive to add a basement later? Unbelievably so.
Is it expensive to design for parking under the building? Yes. One level is not wildly more expensive, but surface parking is as cheap as it gets. More than one level usually results in 10Xs the cost of surface parking.
So when you are asked a 'how expensive is it' question, phrase your response in terms of, "Well, it is certainly more expensive than what is usually done."
You will save yourself some snipe hunting.