I am after a source that allows one to treat one's house as all within four amos l'chatchila, with respect to nagel vasser (hand washing in the morning).
The Mishna Brura in OC 1 says:
י"א דלענין זה אמרינן כולא ביתא כד' אמות דמי אבל אין לסמוך ע"ז כ"א בשעת הדחק.
"There are those who say that with regard to this (washing hands), we say that the entire house is as 4 amos (cubits), but one should only rely on this when forced."
The Aruch HaShulchan in OC 4 says:
מפני שיש מחמירים ומזהירים ע"פ הזוהר שאסור לילך ד' אמות בלא נט"י
"Because there are those who are stringent and are careful acc. to the Zohar that it is forbidden to walk 4 amos without washing the hands."
Rav Avigdor Nebenzahl, in his commentary on Mishna Brurah, "Beyitzchak Yikarei" quotes an oral tradition from his rebbe, Rav Shlomo Zalman Auerbach, that goes back to the Gra that all Ruach Ra (evil spirits) of the Zohar were batel (nullified) after the killing of Avraham ben Avraham the Ger ( http://en.wikipedia.org/wiki/Avraham_ben_Avraham See also the paragraph starting "It is" in the wikipedia article.) Thus according to this there is no need to quickly wash one's hands in the morning because there is no Ruach Ra on them.
The real question is- what is the significance of 4 amos?
The Ran (Mes. Shabbos, 31b in the Ran "Vehamotzi...") says that the reason why transferring >4 cubits in a public domain is not mentioned in the mishna as a major melacha is that it is merely an offshoot of "motzi"- transferring from a private to a public domain. Since a person in a public domain has an halachic ownership of a surrounding 4 amos, every 4 amos is considered a different domain. One who carries more than 4 amos accomplishes the same as a "motzi".
So walking >4 amos w/o washing may be less of an issue of measurement and more of place: Don't leave your domain without washing. >4 cubit inside a house would not be an issue.