“May the roof above us never fall in, and may we friends beneath it never fall out” is an Irish toast/blessing that has been printed in many images. Authorship is unknown.
         
“Here’s to the roof we are under; may it never fall in, and may those that are under it never fall out” was printed in The Idaho Statesman (Boise, ID)—from the London Evening Standard—on February 25, 1912. “May the roof over your head never fall in, and those beneath it never fall out” was printed in the Milwaukee (WI) Journal on November 6, 1960. “May the roof above never fall in and the folks below never fall out” was printed in the Morning Advocate (Baton Rouge, LA) on October 31, 1964.
 
     
25 February 1912, The Idaho Statesman (Boise, ID), “Wit and Humor in Rustic Toasts,” second sec., pg. 8, col. 2:
“Here’s to the roof we are under; may it never fall in, and may those that are under it never fall out.”
(From the London Evening Standard.—ed.)
 
26 February 1912, The Day Book (Chicago, IL), pg. 27, col. 2:
OLD ENGLISH TOASTS
Here’s to the roof we are under; may it never fall in; and may those that are under it never fall out.
 
6 November 1960, Milwaukee (WI) Journal, “When Toasting, Here’s How! (UPI), pt. 4, pg. 2, col. 3:
Included is a fine toast for the host:
 
May the roof over your head never fall in
And those beneath it never fall out.
 
31 October 1964, Morning Advocate (Baton Rouge, LA), Clayton Rand column, pg. 6-A, col. 2:
A good one comes by way of New South Wales: “May the roof above never fall in and the folks below never fall out.”
 
Google Books
Electricity on the Farm
Volume 46
1973 (This Google Books date may be incorrect.—ed.)
Pg. ?:
A family toast: “May the roof above never fall in and the folks below never fall out.”
 
17 March 1978, Detroit (MI) Free Press, “A toast to good whisky” by Tom Bevier, pg. 3A, col. 2:
“May the roof above us never fall in and may all of us friends gathered below never fall out.”
 
27 November 1980, Columbia (SC) Record, “Toasting in ancient times could really protect one’s health” by William Stracener (UPI), pg. 2-C, cols. 4-5:
And for those who might not know what to say, Bonner offered some traditional Irish toasts:
       
“May the roof above us never fall in, and may we friends beneath it never fall out.”
       
30 December 1982, Chicago (IL) Tribune, “Toasting tips [and good tidings] for the holidays” by Carol Haddix, sec, 7, pg. 6, col. 3:
May the roof above you never fall in and your friends gathered below never fall out.
     
Google Books
Guide to the Recommended Country Inns of New England
By Elizabeth Squier
Chester, CT: Globe Pequot Press
1983
Pg. 91:
Over the bar is this sign: “May the roof above us never fall in, and we friends gathered below never fall out.”
 
Google Books
The Book of Irish Americans
By William D. Griffin
New York, NY: Times Books
1990
Pg. 117:
MAY THE ROOF ABOVE US NEVER FALL IN, AND MAY WE FRIENDS GATHERED BELOW NEVER FALL OUT.
       
Google Books
Complete Speaker’s and Toastmaster’s Library
By Jacob Morton Braude
Illustrated by Glenn Van Ekeren
Englewood Cliffs, NJ: Prentice-Hall
1992
Pg. 93:
May the roof above us never fall in, and may we friends gathered below never fall out. — Gaelic toast
 
Google Books
Irish Toasts, Curses & Blessings
By Padraic O’Farrell
New York, NY: Sterling Publishing Company
1995
Pg. 66:
May the roof above us never fall in
And may us good companions beneath it
Never fall out.
 
24 September 2000, Cincinnati (OH) Enquirer, “Women Know How to Party Like the Irish” by Jim Knippenberg, pg. E3, col. 6:
My favorite Irish toast…
Jane: May the roof above you never fall in and your friends gathered below never fall out.