some customer ask how to remove fastener from concrete and won't damage the insulation board? we suggest use a crowbar to remove them. The length of the crowbar body will determine the amount of force it's capable of producing. Obviously the fulcrum will be at the end against the wall where the head turns towards the fastener.With a relatively long crowbar, your leverage will multiply significantly and they will come out much easier.Basically - go to any home goods store and see how long of a crowbar you feel you could live with having around - the longer the better.