I'd say those are all personal preference issues.

I prefer
4,000 sq ft (keeping the comma in case some of the numbers are going to be larger)

to further confuse things you could make a case for
4,000 sq. ft (no stop after ft because it is made up from the first and last letters of the word it is an abbreviation of).

Tim

Chicago Manual of Style (15th edition) says to use "4,000 sq. ft." -- or you can use an exponent 2 on the foot, i.e. ft.2 (the 2 would have to be super-scripted). U.S.-style numbers use the comma to separate thousands, so "4,000" is appropriate, but European-style (except Great Britain) is "4 000" using a half-space instead of a comma (the comma is used instead of a decimal point, so "4 000,098" would be correct).

You could, of course, use the square foot symbol, found at Unicode 23CD, if it's included in your font at all.

EDIT: This is the single straight quote mark intersecting a square through the top. It is used more often in signage as a space-saving alternative to the abbreviation. It is not often used in running text.

If it is longer running text it would be:

Adjective: The 4,000-square-foot house is attractive.
Noun: The attractive house comprises 4,000 square feet.

4,000 sq. ft. is OK for four thousand square FEET, but if you're describing a home which has 4,000 sq. ft., it should be "4,000-square-foot home," since you are using a combination of words, one of which is not an adjective, as an adjective (we covered this subject a few weeks ago).

"I’d say those are all personal preference issues."

That's 100% the problem. The copy was written as 4,000-square-foot and it sat like a lead weight in every paragraph. I changed it to 4,000 sq ft and it gave the text block an even color ... but then there were arguments against omitting the punctuation.

@ oldnick

Your point makes perfect sense. So, I've decided to typeset based on what it looks like in the body text. If it's used as an adjective I'm wrong to set the type this way, two hypens are correct? Can you indicate where I can find that previous thread?

I think this may be the thread mentioned above.

And yes, in my view omitting the hyphens in an adjectival phrase would be wrong. (And apologies - I'm too lazy to phrase this rule as a law.)

I find the phrase awkward to begin with. I'd write something like, "the home, boasting 4000 square feet of living space ..."

Whenever something is grammatically correct but looks wrong on the page, I reword it (with permission of course) instead of compromising the grammar. If the client requires the wording as-is, then bite the bullet and set it their way.

- Lex

Can you please give us the full paragraphs representing each different kind of usage?

You certainly cannot write ft followed by a superscript 2. That means t squared multipled by f.

—
Joe Clark
http://joeclark.org/