I have always specified cast-in-place stair treads for new construction. Now I am collaborating with another firm on a fire station which prefers pre-cast treads with their stair assemblies. In all my years, I have never bothered to consider the benefits of one over the other. Does anyone have any insight on this? Thank you.
I have generally only used precast stair treads in decorative exposed applications - there are options for color, texture, exposed aggregates, etc. If it were a utilitarian exit stair, or if I were just going to carpet over it, I can’t see any reason for it (unless maybe they’re more cost effective).
I have done a lot of multifamily housing, and they use pre-cast treads on wood stringers because they can install them while still in the rough framing stage, use them during construction as access stairs, and are easily repaired at project completion/turnover. Similarly, they offer the landlord a long term low maintenance solution. Adding carpet is sometimes done to reduce noise of people tromping up and down the stairs, but not always and seldom during the entire life span of the stair. As long as the finishes are part of the pre-cast tread mfr’s standard pallet, there is no cost penalty for using their standard finishes including color, aggregates, textures, etc…
Thank you for responding. Your answers are helpful.
Practical: Is there a precaster in vicinity? Are you using a prefab steel stair with pans for casting the concrete? Is there other “formed” concrete on project in addition to flatwork?
Exposure: Is this exterior application in climate with freeze-thaw or corrosive atmosphere? I have no proof, but suspect precast PRESTRESSED treads may have longer life. Pay attention to mix design, too.
Thank you, Michael Chusid. These are important considerations I will take into account.
For decorative main stairs, I usually specify precast stairs. Code does not allow open risers so I usually specify some sort of perforated metal.
For egress stairs in commercial and school projects, I specify concrete pan stairs. Many times there is no floor covering, just a concrete sealer.
For wood framed multi-family construction, I specify rough carpentry stairs. Even though this is cheaper than concrete pan stairs and is allowed by Code (if the exit stairwell is fire rated) I still think it is a dumb idea to have combustible exit stairs.
For exterior egress stairs or stairs in a mechanical or industrial application, I typically specify metal grating stairs.
In the SF Bay Area, there was a period of time recently where precast tread/ risers were consistently less expensive, so we used them for Architectural as well as exit stairs. One of the reasons, as Nathan Woods noted, was that they could go in early and be used for construction stairs. Also, there were at least 2 manufacturers within service distance of our projects.
In most cases, factory-produced items have better quality control than site-produced items, and often have better finishes.
I specify them both, at contractor’s option. I’ve got two small paragraphs that go into the steel stair section. One paragraph for each stair type. I honestly don’t care. We care about the warning strips in the stairs, but for back of house stairs, we will accept either.