4 x 12 Stair Stringer In Concrete

In the picture above the concrete was poured around the wood stair stringer. This can cause the wood to rot from moisture.


A good fix for this would be to cut the stringer and install a metal bracket underneath separating the wood from the concrete.

4 x 12 outside wood stair stringer above concrete walkway

Here's an illustration of what the 4 x 12 stair stringer would have looked like originally after it was built and actually sitting on top of the concrete walkway. This would be better than having it sit below the concrete walkway, but isn't the best way to build this type stairway.

I like to install a spacer under the stringers to provide some type of barrier or separation from moisture that can be absorbed through the concrete and into the wood, eventually causing it to rot or worse yet, attract termites.

4 x 1 2 wood stringer with concrete poured around it

Here's a side view illustration of what the stair stringer actually looks like right now, after they removed the concrete walkway and re-poured it around the existing stair stringer. In other words, the existing walkway must've been damaged and needed to be replaced, yet wasn't poured exactly in the same spot.

Another problem with a situation like this is that concrete and wood both tend to expand and contract and eventually there will be a gap between the concrete and wood, only adding insult to injury. These gaps will allow water to accumulate and form a pool around the bottom of the wood stair stringer.

This would be a bigger problem in areas where it rained often or where water was sprayed on a regular basis from sprinklers or cleaning the concrete walkway with a garden hose than it would in drier climates.


 Damaged 3 x 12 Stair Tread