The owner may waive a provision of the contract providing for a certificate by the architect or engineer.1 Such provision may be waived by express agreement between the property owner and the contractor, setting aside an estimate which has already been made.2 The necessity of producing a certificate may also be waived by the conduct of the parties without specific agreement.3 Thus the conduct of the owner in inspecting and approving material about to be used by the contractor,4 or in taking charge of the building himself under a clause in the contract permitting him so to do,5 or in ignoring the clause providing for such certificate throughout the performance of the contract,6 or wrongfully breaking the contract and preventing performance,7 waives such provision. The provision of a contract which requires the certificate of two architects, is waived where such architects who were partners dissolve the partnership, where the property owner refused to permit one of the architects to render further services, and where he accepts the certificates of the other architect for intermediate payments without objection.8 The necessity of obtaining a certificate is waived where payment is refused absolutely on grounds other than the failure to obtain the certificate.9 The fact that the owner has made one payment without requiring such certificate, does not waive the production of such certificate to obtain subsequent payment,10 although his habitual course of action in making payments repeatedly without insisting on such certificate or approval is said to operate as a waiver.11 A certificate given by an architect for an instalment which is to be paid when the building is completed, does not waive the production of his certificate for instalments due by the terms of the contract thereafter.12 The fact that the occupants of a building were permitted to make use of an elevator, does not waive a provision in the contract under which it was constructed, requiring the certificate of an architect as a condition precedent to payment therefor.13 If a contract for repairs provides for payments only on certificate of an architectural engineer, the act of the owner in making use of the building after it has been repaired does not of itself operate as a waiver of the condition requiring such certificate;14 and no recovery can be had unless such certificate is produced.15

Transpor. & Mfg. Co. v. Franklin Ins. Co., 35 W. Va. 666, 14 S. E. 237; Cleav-enger v. Franklin F. Ins. Co., 47 W. Va. 595, 35 S. . 908; Medley v. German-Alliance Ins. Co., 55 W. Va. 342, 2 Am. & Eng. Ann. Cas. 99, 47 S. E. 101; Houseman v. Home Ins. Co., 78 W. Va. 203, L. R. A. 1917A, 299, 88 S. E. 1048; Pauley v. Sun Ins. Office, 79 W. Va. 187, L. R. A. 1918E, 473, 90 S. E. 652.

4 Corgan v. George F. Lee Coal Co., 218 Pa. St. 386, ,120 Am. St. Rep. 891, 67 Atl. 655.

5 Corgan v. George F. Lee Coal Co., 218 Pa. St. 386, 120 Am. St. Rep. 891, 67 Atl. 655.

6 Taylor v. Supreme Lodge, 135 Mich. 231, 106 Am. St. Rep. 392, 97 N. W. 680.

7 Taylor v. Supreme Lodge, 135 Mich. 231, 106 Am. St. Rep. 392, 97 N. W. 680.

"As to the question arising out of the first contention, it may be stated that a waiver of this defense was clearly made out. After the death of Mr. Taylor, it appears that the defendant's officers were in correspondence with Dr. Pitcher, and were informed by him that he had treated Mr. Taylor for an acute ailment some four or five years earlier. With this information before them, they wrote plaintiff's attorney, in response to a letter demanding a settlement of the claim, declining on the distinct ground that John I. Taylor never paid an assessment. No mention of any other defense is made, the ground of refusal being distinctly stated that the deceased never became a member of the order. This constituted a waiver of other known defenses, and defendant will not, after expense of suit has been incurred, be permitted to shift ground, and assert additional grounds of defense." Taylor v. Supreme Lodge, 135 Mich. 231, 106 Am. St. Rep. 392, 97 N. W. 680 [citing, Marthinson v. Insurance Co., 64 Mich. 372, 31 N. W. 291; Towle v. Insurance Co., 91 Mich. 219, 51 N. W. 987, and Burnham v. Casualty Co., 117 Mich. 142, 75 N. W. 445].

1 Illinois. Andrew Lohr Bottling Co. v. Ferguson, 223 Ill. 88, 114 Am. St. Rep. 305, 79 N. E. 35; Expanded Metal

Fireproofing Co. v. Boyce, 233 Ill 284, 84 X. E. 275.

Kansas. Edwards v. Hartshorn, 72 Kan. 19, 1 L. R. A. (N.S.) 1050, 82 Pac. 520.

Maryland. Filston Farm Co. v. Henderson, 106 Md. 335, 67 Atl. 228.

New York. Smith v. Molleson, 148 N. Y. 241, 42 X. E. 669.

Pennsylvania. Hunn v. Pennsylvania Inst. for Blind, 221 Pa. St. 403, 18 L. R. A. (N.S.) 1248, 70 Atl. 812.

Washington. Lavanway v. Cannon, 37 Wash. 593, 79 Pac. 1117.

2 Edwards v. Hartshorn, 72 Kan. 19, 1 L. R. A. (N.S.) 1050, 82 Pac. 520.

3 Illinois. Andrew Lohr Bottling Co. v. Ferguson, 223 Ill. 88, 114 Am. St. Rep. 305, 79 X. E. 35.

Missouri. Standard Stamping Co. v. Hemminghaus, 157 Mo. 23, 57 S. W. 746.

New York. Campbell v. Coon, 149 N. Y. 556, 38 L R. A. 410, 44 N. E. 300.

Washington. Lavanway v. Cannon, 37. Wash. 593, 79 Pac. 1117.

Wisconsin. Ashland, etc., Co. v. Shores. 105 Wis. 122, 81 X. W. 136; Boden v. Maher, 105 Wis. 539, 81 X. W. 661.

4 Standard Stamping Co. v. Hemming-haus, 157 Mo. 23, 57 S. W. 746.

5 Campbell v. Coon, 149 X. Y. 556, 38 L. R. A. 410, 44 X. E. 300; Hunn v. Pennsylvania Inst. for Blind, 221 Pa. St. 403, 18 L. R. A. (N.S.) 1248, 70 Atl. 812.

6 Ashland, etc., Co. v. Shores, 105 Wis. 122, 81 N. W. 136; Boden v. Maher, 105 Wis. 539, 81 X. W. 661; Halsey v. Waukesha Springs Sanitarium, 125 Wis. 311, 110 Am. St. Rep. 838, 104 N. W. 94.

7 West v. Luda, 69 Conn. 60, 36 Atl. 1015.

Contra, Mitchell v. Dougherty, 86 Fed. 859.

8 Lavanway v. Cannon, 37 Wash. 593, 79 Pac. 1117.

9 Andrew Lohr Bottling Co. v. Ferguson, 223 Ill. 88, 114 Am. St. Rep. 305, 79 X. E. 35.