We are remodeling an old farmhouse, probably built between 1890 and 1900. Most of the floors are solid and sound, except that they are tounge and groove boards. These floors are not very smooth and we want to lay carpet and linoleum. To do so we need to put down subflooring to make the floors smooth. My question is what thickness of subflooring should we use, since it will only serve as a smooth surface and not actually the support.