Budget estimates for determining the estimated cost for the buildingsto be constructed or restored are significant documents that provide dataconcerning building materials and terminology. This article analyzes thebuilding materials and terminology encountered in the budget estimatesfor Hagios Baseliesos (Aya Vasil) Church, the Armenian Girls and BoysSchool and the Prison to be constructed in Izmit. These estimates, whichdate from 1888, 1909 and 1912 respectively, were prepared by the Municipality of Izmit.As a result of the research, it has been found that the building materialsspecified in these estimates are local and imported materials in conformitywith the construction techniques of the period. Similar researches to beconducted on building materials based on budget estimates will supportsuch conclusions and will contribute to the determination of the rate anddiversity of use of building materials in Ottoman architecture and the identification of regional differences.