
160 S.E.2d 542 (1968)
1 N.C. App. 181
WM. MUIRHEAD CONSTRUCTION COMPANY, Inc.
v.
HOUSING AUTHORITY OF the CITY OF DURHAM, North Carolina, and National Surety Corporation.
No. 68SC25.
Court of Appeals of North Carolina.
April 24, 1968.
*546 Edwards & Manson, by Daniel K. Edwards, Durham, for defendant appellant Housing Authority.
Kennon & Kennon and Robert D. Holleman, Durham, for plaintiff appellee.
BRITT, Judge.
Several of appellant's assignments of error relate to the admission of evidence by the trial judge, sitting as judge and jury.
In a trial before the judge, sitting without a jury, the ordinary rules as to the competency of evidence applied in a trial before a jury are to some extent relaxed, for the reason that the judge with knowledge of the law is able to eliminate from the testimony he hears that which is immaterial and incompetent and consider that only which tends properly to prove the facts to be found. Stansbury, N.C. Evidence 2d, § 4A; Harris and Harris Construction Co. v. Crain and Denbo, Inc., 256 N.C. 110, 123 S.E.2d 590. There is a presumption that if incompetent evidence was admitted, it was disregarded and did not influence the judge's findings. Stansbury, N.C. Evidence 2d, § 4A; Wachovia Bank v. Wilder, 255 N.C. 114, 120 S.E.2d 404. For the most part, the testimony complained of were mere summarizations of portions of the documents properly introduced in evidence. We find no prejudicial error in the admission of the testimony complained of.
In its brief, appellant asserts that aside from procedural matters, the issue might be stated as being whether the plaintiff was right in renouncing its bid because the defendant Housing Authority did not agree with plaintiff that unit price for "borrow" should be included in the pre-negotiated unit prices. Although this may be an oversimplification of the issue, it approaches the heart of the controversy.
Appellant assigns as error the refusal of the trial judge to grant its motion for nonsuit at the close of plaintiff's evidence and renewed at the close of all the evidence. We hold that the evidence was sufficient to withstand the motion for nonsuit and this assignment of error is overruled.
Appellant's remaining assignments of error relate to the findings of fact, conclusions of law and judgment entered by Judge Bailey. We will consider these assignments as a whole.
The trial court concluded that the bid documents prepared by appellant or under its direction were ambiguous and unclear as to the question of off-site borrow and that no meeting of the minds of the contracting parties, plaintiff and defendant Housing Authority, ever occurred. The evidence in the record justifies this conclusion.
One of the essential elements of every contract is mutuality of agreement. There must be neither doubt nor difference between the parties. They must assent to the same thing in the same sense, and their minds must meet as to all the terms. If any portion of the proposed terms is not settled, or no mode agreed on by which they may be *547 settled, there is no agreement. Croom v. Lumber Co., 182 N.C. 217, 108 S.E. 735; 13 C.J. 264; 17 C.J.S. Contracts § 31, p. 635. Unless an agreement to make a future contract is definite and certain upon the subjects to be embraced therein, it is nugatory. Consequently, the acceptance of a proposition to make a contract, the terms of which are to be subsequently fixed, does not constitute a binding obligation. Croom v. Lumber Co., supra.
Defendant Housing Authority contends that G.S. § 143-129 is explicit that once the award is made there is a binding contract. In the case before us, the contract itself altered the effect of this statute. The trial court found that the contract documents prepared by defendant Housing Authority went beyond the requirements of the statute and imposed additional conditions of award.
An offer to enter into a contract in the future must, to be binding, specify all of the essential and material terms and leave nothing to be agreed upon as a result of future negotiations. Young v. Sweet, 266 N.C. 623, 146 S.E.2d 669. There must be no lack of identity between offer and acceptance, and the parties must appear to have assented to the same thing in the same sense. Richardson v. Greensboro Warehouse & Storage Co., 223 N.C. 344, 26 S.E.2d 897, 149 A.L.R. 201. The trial court found that no unit price for off-site borrow nor for several of the listed unit price items were agreed upon, therefore, defendant Housing Authority attempted to accept the offer on terms different from those submitted by the plaintiff.
The heart of a contract is the intention of the parties. In construing contracts, it is a well-established rule that an ambiguity in a written contract is to be inclined against the party who prepared the writing. Salem Realty Co. v. Batson, 256 N.C. 298, 123 S.E.2d 744, and cases cited therein.
The trial court determined that the terms of the contract documents are ambiguous. It found that the minds of the parties never met on a material point. This was vital to the consummation of a contract and failure of the minds to meet resulted in no contract. Here the contract documents, including plans and voluminous specifications, were prepared by the defendant Housing Authority or its agents. Any ambiguities found therein must be resolved against it. Coulter v. Finance Co., 266 N.C. 214, 146 S.E.2d 97.
The trial in the Superior Court was without prejudicial error and the judgment of Judge Bailey is
Affirmed.
MALLARD, C.J., and BROCK, J., concur.
