My dad is work at home.

Yes, it can be used as a phrase, but it must be said quickly as if "work at home" is one word. Dashes should be used. Another common example is: "Stay-at-home". A stay-at-home mom is a homemaker. Hope this helps illustrate it.

Still, stay-at-home is an adjective. "My mom is a stay-at-home mom". Work-at-home is still an adjective, so can't be used by itself.

Well, it's perfectly reasonable to have "my dad is [adjective]"--my dad is old, my dad is tall, etc. But I agree that it is awkward at best to have this hyphenated adjectival phrase hanging off the end of this sentence, even with the hyphens.

OK, Pierre, to make it perfectly clear...

We're considering, I gather, the sentence, "My dad is work at home." This sentence is grammatically incorrect.

Either sentence you suggested as an alternative is grammatically correct.

I agree that the statement is awkward and gramatically-incorrect in any instance. Proper use or understanding of spoken slang should be every speaker's eventual goal, but I stand corrected for offering it as an example of correctly-written english. :)

Is your friend's first language English? What he said was wrong, yes.

Looks VERY awkward, I can't see too many people accepting it.

MY DAD IS WORK-AT-HOME would make sense, although I can't say I've heard that phrase before.

The hyphenation is the important thing to get the meaning across, otherwise it looks like someone trying to say "My Dad works at home" in broken English.

Dave, the one and only way that that could be a correct English statement is in something like the following situation:

Say you are a secretary in HR (Human Resources, or Personnel) and you are classifying your employees into two groups that you are calling "work in office" and "work at home." Your father is an employee of your company, and he works at home. So Sally might be "work in office," and your father might be "work at home." If someone asked you what classification your father belonged to, you might tell them, "My dad is 'work at home.'"

You would still sound strange, and a better rendition would still be, "My dad works at home" or, "My dad is a 'work at home.'"

No. The correct version is "My dad works at home."

It is an equational sentence.
My dad = work at home

This is especially true if you have to clean up after him. "Work at home" is colloquial.

Home makers use the phrase quite often I believe. Mothers often use it to descibe their little ones who are always making a mess. I have heard it in different parts of the U.S.

ishtarbaba, I'm afraid I have no clue what your point is here.

My dad works at home OR My dad is work-at-home.

i think depend on how you translate into your language. i hmong so that means the same.

It sounds pretty bad to me.

The hyphens suggested by others are correct, but I wish to add that in a verbal dialogue, you would have understood clearly.

To use my personal phonetics:
"My dad iz wurk at hoem"
As opposed to:
"My dad iz wurkathoem"

There would be less verbalized space between the ending words, as evidenced by the written hyphens.