[5] The "construction given the contract by the acts and conduct of the parties with knowledge of its terms, before any controversy has arisen as to its meaning, is entitled to great weight and will, when reasonable, be adopted and enforced by the courts." ( Woodbine v. Van Horn, 29 Cal.2d 95, 104 [ 173 P.2d 17]; Gillespie v. City of Los Angeles, 36 Cal.2d 553, 561 [ 225 P.2d 522]; Trottier v. M.H. Golden Construction Co., 105 Cal.App.2d 511, 516 [ 233 P.2d 675].) [4b] Here the construction placed by the parties upon their agreement is not only reasonable, but a contrary construction would not reflect the ordinary meaning of the language used. (Civ. Code, § 1644)
[1] The case before us requires a determination of the effect of the language of the subcontract whereby Ruane agrees to be bound by "the general conditions of the aforesaid specifications and all conditions" of the prime contract "insofar as they are applicable to this particular work." Of course these provisions are valid and binding on Ruane. ( Enochs v. Christie, 137 Cal.App. 2 d Supp. 887 [291 P.2d 200]; Gray v. Cotton, 166 Cal. 130 [ 134 P. 1145]; Trottier v. M.H. Golden Construction Co., 105 Cal.App.2d 511, 515-516 [ 233 P.2d 675].) The question is, what are the effects of these provisions?
( Cadigan v. American Trust Co., 131 Cal.App.2d 780, 787 [ 281 P.2d 332]; Citizens Nat. Trust Sav. Bank v. Beverage Co., 126 Cal.App. 550, 554 [ 14 P.2d 821].) [3] The general principle of joint consideration of several instruments as one agreement is applicable whether they expressly refer to each other ( Mayers v. Loew's, Inc., 35 Cal.2d 822 [ 221 P.2d 26]; Roberts v. Security Trust Sav. Bank, 196 Cal. 557, 563 [ 238 P. 673]; Trottier v. M.H. Golden Construction Co., 105 Cal.App.2d 511, 515 [ 233 P.2d 675]; Holbrook v. Fazio, 84 Cal.App.2d 700 [ 191 P.2d 123]; Valley Const. Co. v. City of Calistoga, 72 Cal.App.2d 839, 841 [ 165 P.2d 521]; Bell v. Rio Grande Oil Co., 23 Cal.App.2d 436, 440 [ 73 P.2d 662]; Beedy v. San Mateo Hotel Co., 27 Cal.App. 653, 661 [ 150 P. 810]), or it appears from extrinsic evidence that they were executed as a part of one transaction. ( People v. Ganahl Lumber Co., 10 Cal.2d 501, 507 [ 75 P.2d 1067]; Tuso v. Green, 194 Cal. 574, 581 [ 229 P. 327]; Merkeley v. Fisk, 179 Cal. 748, 754 [ 178 P. 945]; Cadigan v. American Trust Co., 131 Cal.App.2d 780, 786 [ 281 P.2d 332]; Storm Butts v. Lipscomb, 117 Cal.App. 6, 15 [ 3 P.2d 567]; Hancock v. Clark, 56 Cal.App. 277, 279 [ 204 P. 1098]; Torrey v. Shea, 29 Cal.App. 313, 316 [ 155 P. 820].)
[5] The practical construction which the parties themselves placed upon the language of the note is persuasive evidence of their intent. ( Vogel v. Bankers Bldg. Corp., 112 Cal.App.2d 160, 166 [ 245 P.2d 1069]; Trottier v. M.H. Golden Construction Co., 105 Cal.App.2d 511, 516 [ 233 P.2d 675].) In the instant case, the parties apparently treated the note as a demand note, for payments (both principal and interest) were made and accepted in varying amounts at irregular intervals during Talbot's lifetime and after his death.
Moreover, if "the plans and specifications are by express terms made a part of the contract, the terms of the plans and specifications will control with the same force as though incorporated in the very contract itself." Valley Construction Co. v. City of Calistoga, 72 Cal.App.2d 839, 165 P.2d 521 (1946); see also, Trottier v. M.H. Golden Construction Co., 105 Cal.App.2d 511, 233 P.2d 675 (1951). In the instant case, the parties' subcontract was a one-page, short-form document, which by its express terms, required appellant to furnish work in conformity with the plans and specifications of the prime contract.