Bar on unwritten escalation clause

The contractor, who undertakes to prepare the site plan, drawings or description of any work, for a specified price shall not be entitled to demand anything more, even though there may be increase in the price of materials or in the wages, and even though there was a change in the job, in relation to the plan, drawing or the description, if this alteration and the cost thereof have not been agreed in writing with the owner. § Sole paragraph - Where the increase is above 20 percent and arises from the devaluation of currency, the contractor shall have right to rescind the contract, so long as the owner is not agreeable to compensate the contractor for such excess; and in the reverse case, the owner shall have similar right.