The word housebuilder is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 21
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (50 words)
bedsore, beerish, beholds, bloused, blueish, blushed, blusher, boilers, bolides, boulder, bousier, bridles, broiled, bruised, brushed, builder, bulrush, bushier, delouse, derbies, disrobe, doubler, doubles, dubious, duelers, edibles, eluders, herbose, herbous, heroise, hideous, holders, hurdles, leisure, lousier, oilseed, reboils, rebuild, rehides, rehouse, reoiled, reshoed, residue, resoled, rosebud, sobered, soldier, subduer, subrule, ushered