transverse 3" nominal spacing I assume that is upright to product so water can work its way down. If product is only stored on the floor level does the same nominal transverse flue space need to be maintained. Potentially we are looking to use 96" beams but we have some wide product that is 92.5" wide that will only be stored on the floor level. this means we only have 1.75" from upright to product either side. Above would have correct flue space but just the floor level would be tighter.