Piers/footings under stair landing on paving stone patio?
I am putting in a stone patio at ground level with a 7 steps going down from a small (3' x 11') platform deck coming out of the house. The stairs will be approx 8 feet wide. My question is: do I need to put piers/footings under the bottom of the stairs or can I land it directly on the paving stones?
I live in Montreal so frost is a reality. But the paving stones (slabs) will be sitting on approx 9" deep of crushed and compacted 0-3/4" stone (standard method here) to minimize heaving. My intended plan was to land the stairs directly on top of the patio stones.
Local code does not seem to specify one or the other but I've heard arguments supporting each approach.
1) Piers/footings: Sure, the stairs are definitely not going to rise/fall if the patio stones do. But, on the flip-side, the bottom rise between patio and first step would vary by that same amount and could cause a stepping hazard.
2) Land the stairs on top of the patio stones: Attachment of top of stringers to the deck needs to be able to handle some movement, but reality is that 1/2" movement at bottom of stringers translates to a tiny change in angle of the stringers. Also, this approach assures that the bottom step height is consistent even if the patio moves a small amount.