1 EXHIBIT 12 AMERICAN PLUMBING & MECHANICAL, INC. AND SUBSIDIARIES RATIO OF EARNINGS TO FIXED CHARGES (IN THOUSANDS OF DOLLARS) Four Months Four Months Year Ended Three Months Ended Years Ended August 31, Ended Ended December 31, March 31, ------------------------------ December 31, December 31, ------------------ ------------------ 1994 1995 1996 1995 1996 1997 1998 1998 1999 ------- ------- -------- ------------ ------------ ------- ------- ------ ------- CHRISTIANSON (ACCOUNTING ACQUIROR) Earnings: Income before income taxes . . . . . . . . . $ 256 $ 838 $ 1,343 $ 370 $(1,402) $ 1,967 $ 648 $ 449 $ 3,564 Fixed charges . . . . . . 93 133 152 49 52 252 269 165 197 ------- ------- -------- -------- ------- ------- ------- ------ ------- $ 349 $ 971 $ 1,495 419 $(1,350) $ 2,219 $ 917 $ 614 $ 3,761 ======= ======= ======== ======== ======= ======= ======= ====== ======= Fixed Charges: Interest expense . . . . . $ 10 $ 72 $ 92 $ 29 $ 33 $ 102 $ 116 $ 37 $ 27 Portion of rental cost representing interest . 83 61 60 20 19 150 153 128 170 ------- ------- -------- -------- ------- ------- ------- ------ ------- $ 93 $ 133 $ 152 49 $ 52 $ 252 $ 269 $ 165 $ 197 ======= ======= ======== ======== ======= ======= ======= ====== ======= Ratio of earnings to fixed charges . . . . . . . . . 3.7x 7.3x 9.9x 8.6X --x 8.8x 3.4x 3.7x 19.1x ======= ======= ======== ======== ======= ======= ======= ====== ======= PRO FORMA COMBINED: Earnings: Income before income taxes . . . . . . . . . $18,710 $ 8,395 Fixed charges . . . . . . 16,412 4,114 Preference dividends . . . (1,363) (341) ------- ------- $33,759 $12,168 ======= ======= Fixed Charges: Interest expense . . . . . Amortized premiums, discounts and capitalized expenses $14,201 $ 3,550 related to debt . . . . 500 125 Portion of rental cost representing interest . 348 98 Preference dividends . . . 1,363 341 ------- ------- $16,412 $ 4,114 ======= ======= Ratio of earnings to fixed charges . . . . . . . . . 2.1x 3.0x ======= =======