in chicago, i have a raised patio (442 sq ft) that is set at 11" below the sliding door threshold. as a result, we need to raise patio surface 4". my questions are, if we build up a 2.5 " motar bed on the existing conrete patio and lay 1.5" bluestone uopn the motar bed, 1) will this construction sustain itself thru freeze/thaw cycles? 2) should we, or should not use a moisture liner system between the motar and stone?