I am constructing new bunglow. I have 7'.6" X 7'.6" square availabe for the starcase. Earlier I was insisting for concrete staircase. Now it is not possible to cast staircase in concrete as there is no beams available for support on the 2 side walls which are common. Please suggest decent,sturdy ,long life fabricated staircase for me. My first slab is at 12' heightt and remaining 2 are 10' height. Totaly ground + 2 floores. Normally I have seen the fabricated staircase which make lot of vobration noise during use. Please suggest center stringer staircase. How to dampen the noise from the stair steps while walking?