Carpet don't need 12mm underlay, & i'll start using ply strips when the shops that sell the 12mm underlay supply ply strips to highten the gripper...
He messsd up, he's cut them short, ,
Minmum £7 M2, for thin ones, £8 for thicker sisals/seagrass, £10-£12 for thick coirs plus prep ply/hardboard ect + ahedesive costs.