The Stove I wish to purchase ( Hearthstone Shelburn) has a listed side clearance of 13" to combustibles with double wall connector. I am just short of that by 2 inches. The NFPA states that clearances can be reduced by 66% given their wall shield suggestions, but at the bottom of the page it states that 12 inches is the minimum reduction. Is that for unlisted stoves or all stoves?