Md. Code, Real Property § 10-202

(a) Express warranties by a vendor are created as follows:

(1) Any written affirmation of fact or promise which relates to the improvement and is made a part of the basis of the bargain between the vendor and the purchaser creates an express warranty that the improvement conforms to the affirmation or promise.

(2) Any written description of the improvement, including plans and specifications of it, which is made a part of the basis of the bargain between the vendor and the purchaser creates an express warranty that the improvement conforms to the description.

(3) Any sample or model which is made a part of the basis of the bargain between the vendor and the purchaser creates an express warranty that the improvement conforms substantially to the sample or model.

(b) To create an express warranty, it is not necessary to use formal words, such as “warranty” or “guarantee”, or that there be a specific intention to make a warranty. However, an affirmation merely of the value of the improvement or a statement purporting to be an opinion or commendation of the improvement does not create a warranty.

(c) If an express warranty is made under subsection (a) of this section, neither words in the contract of sale, the deed, other instrument of grant, nor merger of the contract of sale into the deed or any other instrument of grant is effective to exclude or modify the warranty. At any time after the execution of the contract of sale, the warranty may be excluded or modified wholly or partially by a written instrument, signed by the purchaser, setting forth in detail the warranty to be excluded or modified, the consent of the purchaser to exclusion or modification, and the terms of the new agreement with respect to it.