Thanks Goldspoon, It appears you may have given me my answer, It is a lot cheaper than vermiculite and I can get it locally.
An engineer came yesterday to quote to fit the stove said that I did not need to do anything to as it would be far enough away from the wall at 180mm to be well within...
New to here so please be gentle.
I am having a wood burner installed (Morso 6140 by a Hetas installer) but I am doing the hearth and the surround. (No fireplace) The problem is that I would like to have the wall behind as plain as possible.
One possibility is to use Vermiculite fireboard but...