Mystery undercarpet sheet

[splutter]

Hi. I have just bought an old house with a 1960s extension in Scotland. I lifted the carpet and underlay in one of the rooms yesterday, to discover sheets of an odd material nailed to the floorboards. I have attached two photos. It has been severly dented by feet of bed etc, so is obviously a bit pliant, but quite firm to walk on. Can anyone tell me what it is made of please, and its purpose? Thank you! Graham

 

[petej]

From your picture it looks like "hardboard" and is often used to flatten the floor for the carpet when the old floor boards are split,have large gaps between them or are just in poor condition.

It is usually about 3/16" thick and is very smooth on one side and textured on the other.

Pete