GUNITE
VERSUS
SHOTCRETE
They are not two products and the comparison is not the choice it is usually presented as. Gunite and shotcrete are placement methods rather than materials, both projecting concrete or mortar through a nozzle at high velocity so that the force of placement is what compacts it, and the real difference between the two names is where the water meets the material.
Two names, one family of placement methods. The versus is doing work the materials are not.
Shotcrete is the term the ACI documents use. Gunite began as a proprietary product name that the pool trade still applies to the dry mix version of the same process. In the dry mix process the water meets the material at the nozzle. In the wet mix process the water is batched in before the material reaches the nozzle. Both are placed by a nozzle operator working by hand and by eye, which puts the crew inside the structure rather than on the surface of it. That last sentence is the reason this page exists, and it matters more than which name is on the quote.
One is a specification term. The other is a brand from 1910.
The confusion is historical rather than technical, and knowing that removes most of the anxiety this question tends to carry.
Shotcrete is what the standards call it. It is the term used in ACI's documents, including ACI 506.2, the Specification for Shotcrete, and ACI PRC-506-22, the Shotcrete Guide published November 2022. If you are reading a specification rather than a sales page, this is the word you will meet.
Gunite started as a trade name. ACI's own guide records that gunite was the proprietary name given to the sand and cement product of a cement gun design introduced in 1910. The pool trade kept the word and now applies it to the dry mix version of the process.
So the two words are not parallel. One names a family of placement methods in the standards. The other names one branch of that family in one industry's habit of speech. Presented side by side with a versus between them, they imply a product comparison that the underlying documents do not support. The standalone definition is at the PSIP dictionary.
Where the water meets the material. That is the distinction.
There is a real difference underneath the naming confusion, and it is narrower and more specific than the marketing version.
The water meets the material at the nozzle.
Dry material travels the hose and is hydrated at the point of placement, which puts the water decision in the hands of the operator, in real time, at the nozzle.
The water is batched in before the material reaches the nozzle.
The mixture travels the hose already hydrated, which moves the water decision upstream into batching, where it is a documented quantity rather than a live adjustment.
That is why arguing the two names against each other misses the variable that actually moves. Both methods are placed by a nozzle operator working by hand and by eye, which puts the crew inside the structure rather than on the surface of it. On a poured slab a finishing crew works on top of concrete that is already placed. On a shot shell, the person holding the nozzle is producing the structure as they go.
We do not take a side on which method is better.
This is worth saying plainly rather than burying, because a page titled with a versus is expected to pick one and this one is not going to.
PSIP does not take a position on which method is better. The protocol records which one was used, what was in it, and who placed it.
That is not a dodge and it is not neutrality for its own sake. It follows from what the evidence supports. Both processes are covered by the same ACI specification family, both are in ordinary professional use, and both are capable of producing a sound shell or an unsound one depending on execution. A body that scored the method rather than the record would be making a judgment its own sources do not license.
What is recordable is not in dispute: which process was used, what material was placed, who was on the nozzle, and what the conditions were on the day. Those are facts about your pool rather than opinions about an industry, and they exist for only as long as the shell is exposed.
Five questions worth more than the one you came with.
If you are choosing a builder and this question was going to be one of your filters, these will separate candidates better than the method name will.
Why the second half is the real question: shell placement is very commonly subcontracted, so the company selling you the pool may not be the company producing the structure. What you want is a name, because that is the contractor of record for the shell.
Why it is the highest leverage question on this page: the material is placed by hand and by eye, and compaction happens at the nozzle in real time. The operator is not applying a finish to a structure. They are producing the structure. Asking this signals you understand where the quality is decided, which changes the conversation.
Why here specifically: shadowing behind congested reinforcing steel is the region where consolidation is hardest to achieve and hardest to see. Listen for: awareness that it is a known concern, and how they handle it, rather than a reassurance that it never happens.
Why the shell day is the whole ballgame: the shell is covered by an interior finish within weeks, and from that point it cannot be examined again without removing the finish. Listen for: a specific artifact rather than photographs alone.
Why it belongs on this list: substrate preparation happens twice on a pool, once on the excavated ground before the shell is shot and again on the shell before the finish goes on, and each is preparation for a different trade. That second one sits on the handoff between two companies, which is where records most reliably stop.
Every one of those works on a builder who uses either method, which is the point. The method name tells you which family of process you are buying. These tell you whether anyone is going to be able to prove what happened.
We score the record. We do not grade the pool.
This page would be worth less if it ended by telling you the answer is us. So here is exactly what PSIP is and what it is not, in the same terms as everything above.
- ×PSIP does not endorse a placement method. Not dry mix, not wet mix, not a brand of equipment. The protocol records which one was used, what was in it, and who placed it.
- ×PSIP does not say a certified builder builds better pools. A PSIP certified contractor has committed to documenting the work and to retaining the record. That is a statement about their paperwork, not a judgment of their concrete, and treating it as the second thing would make it worth nothing.
- ×PSIP does not rank builders. Records are sorted, never ranked. Sorting is an order you choose and can reverse. Ranking is a judgment made on your behalf, and a body that scores documentation has no basis for making it.
- ×A record is not a warranty. Certification is a documentation and scoring credential. It is not a warranty, guarantee, or insurance of the contractor's work; not engineering or design services; and not a government license or code approval. PSSG does not supervise, direct, inspect, or perform the contractor's concrete work, and is not a party to any contract between the contractor and the customer. The contractor is solely responsible for its own work, methods, safety, code compliance, licensing, and customer relationships. A closeout packet establishes what was specified and what was delivered, which is the factual ground a warranty or a claim would be argued from.
Asked and answered.
They are two names for one family of placement methods rather than two products. In both, concrete or mortar is conveyed through a hose and projected through a nozzle at high velocity onto a surface, so that the force of placement is what compacts it, instead of being poured into forms. The technical difference is where the water meets the material: in the dry mix process, commonly called gunite, the water meets the material at the nozzle, and in the wet mix process the water is batched in before the material reaches the nozzle.
PSIP does not take a position on which method is better. The protocol records which one was used, what was in it, and who placed it. Both processes are covered by the same ACI specification family and both are in ordinary professional use, so the variable that moves is execution rather than the name on the quote.
Shotcrete is the term the ACI documents use. Gunite began as a proprietary product name, and ACI's own guide records that it was the name given to the sand and cement product of a cement gun design introduced in 1910. The pool trade kept the word and now applies it to the dry mix version of the same process.
Execution affects it more than the method name does, and execution is decided at the nozzle. Both processes are placed by a nozzle operator working by hand and by eye, which puts the crew inside the structure rather than on the surface of it, and compaction happens during placement rather than in a step that follows. What is checkable about a given shell is which process was used, what was placed, who placed it, and whether any of that was recorded while the shell was still exposed.
Shell compaction is the consolidation of the concrete as it is placed. In gunite and shotcrete there is no separate compaction step, because the velocity of the material leaving the nozzle is what does the compacting. ACI's specification for shotcrete defines the material as being projected at high velocity onto a surface to achieve compaction, which puts compaction inside the definition rather than in a step that follows it.
Ask, and then ask the questions that carry more information: whether the crew shooting the shell is their own or a subcontractor, who will be on the nozzle, how the reinforcing will be encased where steel is congested, what will be documented on the day the shell is shot, and how the shell surface will be prepared before the interior finish goes on. Those work on a builder using either method.
Pricing varies by region, by crew and by what a given builder already owns and operates, so a general answer would not be a fact about your project. The more useful comparison between two quotes is whether either of them states what will be documented on the day the shell is shot, because that is the part that becomes unrecoverable rather than the part that becomes negotiable.
PSIP cites ACI 506.2, Specification for Shotcrete, from ACI Committee 506, reapproved 2018, and ACI PRC-506-22, the Shotcrete Guide from the same committee, published November 2022. The second one supersedes the older 506R-16 guide, and a search will often return the superseded edition first because it is better linked.
Every term on this page is defined once.
Gunite and shotcrete, shell compaction, pool shell, substrate preparation, reinforcing cage, contractor of record and closeout packet each have a single standalone definition in the PSIP dictionary, with the primary sources behind them.