Traditionally, deck stairs land directly on a patio made of concrete, stone, or a material other than soil to prevent rot and decay. These landings can shift freely with frost movement. Frost movement is the rise and fall of the soil due to underground water freezing and expanding. Recently there have been some concerns regarding frost movement and the stair’s ability to withstand the fluctuations. Typically, stairs have more freedom of movement than the deck, but some builders argue the stairs should be supported just like the deck. This topic is a grey area because it all depends on each deck’s situation.
So what exactly happens when frost movement causes the landing area to move? As the soil moves, it creates a domino effect that moves the landing area, and subsequently the stairs as well. If your deck’s stairs only have a few steps, the movement is insignificant because of their short length. On the other hand, if you have stairs that span several flights and require posts to bear the load, then they will suffer from more exaggerated movement.
Building frost footings (concrete pillars that sink well below the frost line of your area) requires excavation and a lot of man hours. If your stairs are small, frost footings are unnecessary. The expense would not justify the benefit you’d receive. However, if you have several flights of stairs, the frost footings will guarantee minimal movement of the stairs. The footings will provide added security and reduce the chances of the stairs failing.
Stairs are important. They provide access to your deck. Building them properly ensures their reliability and lifespan.
1 thought on “Do You Need Frost Footings For Your Stairs?”
Built house in Northern Ontario and did not note plans did not contemplate need of stairs nor footing for same on clay soil.
Stairs up to verranda are to be 7 ft long and 4 ft wide and will abut icf foundation. My sense if need is to excavate diwn 4 ft to frost line, build 10″ footing on which 8″ concrete blocks will be installed up 4 ft to finish grade level, the excavation then backfilled and on which wood steps as described will be built.
Does this seem right plan for my need?