в русском языке всё как в Америке первый этаж это тот который сразу на земле над ним -- второй у нас в 14-м здании есть 13 этаж поэтому здание называется "четырнадцатиэтажка" а в "девятиэтажке" -- девять этажей на всякий случай лучше уточнить: Я живу в четырнадцатиэтажке но в моём доме нет 13-го этажа.

Вот что написано в Википедии: In all English-speaking countries, however, the storeys in a building are counted in the same way. Thus, for example, the phrase a seven-storey building would mean the same thing in Britain and in the US — namely, a building with seven covered floors, including one at ground level and six at higher levels; even though the topmost of those levels would be called "6th floor" in Britain, and "7th floor" in the US. (http://en.wikipedia.org/wiki/Storey) То есть на определение этажности эта разница не влияет, четырнадцатиэтажный дом так и останется четырнадцатиэтажным. Если считать, что в Англии ground floor- это первый этаж, а за 12 этажом сразу идёт 14 этаж, то по моим подсчётам верхний этаж четырнадцатиэтажного дома будет всё равно the 14th floor. В Америке при условии отсутствия 13 этажа, верхний этаж будет называться the 15th floor.

And in the USA many buildings don´t have 13 th. floor,they skip it.

привет ! I´ve found this for you,in wikipedia Hope it helps. You just say :Third floor please. Numbering Floor numbering is the numbering scheme used for a building's floors. There are two major schemes in use across the world. In one system, used in the majority of Europe, the ground floor is the floor on the ground and often has no number or is assigned the number zero. Therefore the next floor up is assigned the number 1 and is the first floor. The other system, used primarily in the United States, counts the bottom floor as number 1 or first floor. The next floor up then becomes the second floor and so on.[2] Having the first floor above the ground floor means that subterranean levels (often listed with increasing depth as B1, B2..) can be counted without having a gap at 0 (ground). In both systems, the numbering of higher floors continues sequentially as one goes up, as shown in the following table: Displacement from ground level British convention American convention 6 storeys height above ground "6th floor" (6) "7th floor" (7) 5 storeys height above ground "5th floor" (5) "6th floor" (6) 4 storeys height above ground "4th floor" (4) "5th floor" (5) 3 storeys height above ground "3rd floor" (3) "4th floor" (4) 2 storeys height above ground "2nd floor" (2) "3rd floor" (3) 1 storey height above ground "1st floor" (1) "2nd floor" (2) ground level "Ground floor" (0 / G) "Ground floor" or "1st floor" (G / 1) 1st basement floor "Basement floor" (-1) Varies (P1, B1, etc.) 2nd basement floor "Basement floor" (-2)