Old floorboards have a rise near one wall

[Aorman]

I have just ripped up my old carpet in readiness for a wooden floor, to see that on one sde of the room, next to the hearth, the flloorboards have a rise in them of about 20mm over 36 inches. In other words it is like a shallow bump about 6 inches from front to back, and about 36 inches from side to side. If you tip a saucer upside down, you'll get the idea.

Anyway, I am going to lay 6mm plywood on top of the floorboards, and now would like to know if I need to do anything else regarding the lump/rise.

Thanks

[xerxes]

I suggest you investigate further: remove the affected board(s) and check to find out how to remedy the problem.

It could be that you have a board which wasn't fixed down properly, and it has cupped; in that case replacing it with a flat board will solve the problem.