Adams Stirling PLC


Reasons for Failure. In most cases, it takes 10 to 20 years for the failure of a stair to occur. Failure is most often due to exposure to rain and sun and accelerated by poor maintenance or poor design. Failure can result in loose stair treads which can lead to falls or water intrusion and dry rotted wood.

Building Codes. Depending on the extent of the repair, associations may be required to bring the stair into compliance with current code. Current code does not allow stairs to be as steep or narrow as they once were.

Definitions. The following definitions apply to stairs.

Guardrail: The guardrail is designed to prevent falls from stairs of decks greater than 30 inches above the ground. Current code requires the guardrail to be no less that 42 inches high (it was 36 inches before) and designed to prevent a 4 inch diameter sphere from passing through it (it was 6 inches before). The current code also requires the guardrail to be strong enough to resist a 200 pound load along the top of the rail.

Handrail: The wood or steel tube or rod that ascends with the stairs. Handrails are required by code on both sides of an exterior stair. There are very few exceptions to this code requirement. They are required to be of a specific diameter, shape and distance from the wall or guardrail. They are required to extend past the top and bottom of the stair and to terminate in such a manner that a shirt sleeve or bracelet will not get caught on the handrail.

Nosing: Where the riser intersects with the tread.

Risers: The vertical space or surface at the back of each tread which separates one tread from the next tread. Sometimes the riser is open meaning an object can pass through it. Sometimes the riser is closed. Closed risers comply with current building codes, open risers do not comply. The risers are to be consistent in height and have a current code limit of no less than 4 inches high and no greater than 7 inches high.

Stringer: This is the structural beam (wood or steel) that runs parallel to the treads as they ascend. There are times when there is no visible stringer because it is either embedded in a wall or hidden with finish materials.

Treads: The horizontal surface of the stairs that you step on. These can be made of pre-cast concrete (made at a factory), steel, wood or some type of solid (hopefully waterproof) deck coating. The treads are required to be uniform in depth and have a minimum depth of 11 inches to meet current code.

The tread and riser are formed out of one piece of pre-cast concrete.

The concrete tread bolts to the steel angle welded to the steel stringer. If this stair was not under a roof, we would likely see rust where the tread attaches to the steel angle.
This stair does not comply with current codes for tread depth, closed risers, guardrail height or handrail design.

The stair framed of wood and coated with a waterproof coating. The stringers are hidden in the stucco coated guardrail walls.

Water penetrated the stringer where the steel angle supports the pre-cast concrete tread. Thirty years later there was little wood left to support this stair. The red tape and plastic is the destructive testing holes created to determine the extent of the damage.

Dry rot is a fungus which feeds on wood. once it gets started it is difficult to stop and will spread to the deck and living unit. The photos above show the extensive decay of the stair stringers and guardrails. It would just be a matter of time for the entire stair to collapse if left alone.
A new replacement stair is being constructed on the right. A temporary stair which allows ingress and egress for second floor occupants during the construction is located on the left. 

A new stair is on the left and an old stair is on the right. the new stair is wood framed with a waterproof coating. The stair on the right is pre-cast concrete treads connected to stringers covered by the stucco coated guardrails.

Quick tips for managing stairs:

  • Stairs with waterproof coating should be inspected annually to confirm the coating has not been compromised by furniture moving or misuse. Pre-cast concrete stairs should be checked with every painting (3 to 5 years depending on your climate) to confirm the treads are tight and the stringers are structurally sound.
  • Be diligent in maintaining the paint where pre-cast concrete treads touch the stringer and where there are exposed fasteners (bolts, screws, etc.).
  • Replacement or repair of treads typically does not require a building permit. With few exceptions we have found that repair or replacement of stair stringers require building permits.
  • Prior permit experience with stair replacement or repairs in one city does not mean that another city will permit the stairs the same way. Although the building code is a statewide code, the building official in each city is the final interpreter of the code.

Thank you to Smith Architects for providing this information.

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Adams Stirling PLC