When I built a second attached two-car garage (so that I could convert the first one into my wife's art and ballet studio), I set the slab about two inches below that of the house, but made the eve line match. The extra height came in handy for hanging the bikes from the rafters. With 1400 sq. ft. of living space excluding my wife's art studio and with son #2 still living part-time at home, there is no room for bikes in the house.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069