Sloppy pool construction practices

Which of these sloppy construction practices is your pool builder guilty of using? 

No soils reports (even in differential soils)?
Undermining the foundation of a house by digging too close?

Using flexible PVC tubing (meant for portable above grade spas) because they were too lazy to heat bend pipe?

Only install 2-bar bond beams?
Install reinforcing steel or pins in contact with the forms or earth?

Place your pipes directly on the earth, because trenching to place them below grade is too difficult?

Use the same steel schedule for every single project or utilize generic / mail order engineering without regard to surcharges (soil conditions, building foundations, hydrostatic conditions, wind loads, etc) ?
Use flimsy forms that do not provide a solid surface to shoot against (as required by ACI & ASA) ?

If your pool builder does not know why these practices are forbidden or against industry practices, then they need some training and education. Unfortunately, this is an industry of "on the job training"... but if the people they learned from were doing it wrong... the tradition continues !

Did you know that the International Building Code (IBC) and International Residential Codes (IRC) REQUIRE soils reports, project specific structural engineering (structures must be designed to overcome the anticipated loads) and minimum shell thicknesses? Some states have adopted their own more restrictive building codes (but they are based upon the IBC & IRC - e.g. CA & FL).

Most building departments that do not enforce their adopted building codes, do so, out of ignorance. The liability in the event of a failure, falls on the contractor, as the government has immunity. It is your builders responsibility to know the codes and to follow them.

Just because they have done it that way for 35 years, does not make it RIGHT... SAFE or LEGAL.

You should be constantly learning, something new everyday - then putting that into practice.  If you think that you "know it all," then it is time to retire.

I cannot count the number of times that pool builders in various courses or lectures have come up to me after and said, "You know we've been doing it that way for XX years. I never knew that it was wrong," "That explains why we have that type of failure constantly occurring," "I wish someone would have taught me the correct way years ago. It would have saved me thousands of dollars in remedial repairs."

EDUCATION is cheaper that demolition and lost consumer confidence.

No, I'm not saying all of this because I've been sued or have a vested financial interest in any education programs. I am saying this because I want to elevate the practice of building pools and make this industry better. Anyone who knows me, knows that though there are various techniques, there is only one way of doing something - the RIGHT WAY ! 

How do you know that your pool is being built in compliance with the building codes, if the local building inspector does not know what he is looking at?  Hire an independent inspector or "owner's representative" to ensure that your project is built "per code."

Paolo Benedetti, SWD Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management 
Contact the author at: info@aquatictechnology.com or 408-776-8220 
"Creating water as art."™ 
Aquatic Technology Pool and Spa© 
©www.aquatictechnology.com 
All rights reserved.

MINUMUM Swimming Pool Strength Shotcrete Gunite PSI MPA

There are minimum specifications for the strength of swimming pool shotcrete.  

What ever you call it, it's all Shotcrete
All pneumatically applied (sprayed) concrete is called shotcrete, regardless if they are using the wet or dry mix method.  The term "gunite" is often incorrectly used to describe the dry mix method.  The American Shotcrete Association (ASA), which is a sub-organization of the American Concrete Institute (ACI) only recognize the term shotcrete.  And they only refer to the shotcrete "wet" or "dry" methods.

Specifications are the LAW
ACI 318 is incorporated and included in every state building code in the United States.  By statute, this makes the standards of ACI 318 MANDATORY.  So, regardless of the concrete strengths that a structural engineer can justify with their calculations, ACI 318 dictates the minimum strengths.  This is exactly where the problems start... structural engineers think that they are doing their clients and contractors a favor by specifying a lesser strength concrete.  

Concretes that are specified above 2500 PSI require strength validation by a testing laboratory.  The testing lab will obtain samples from the job site and then test them to verify that the proper strengths are met.  2500+ PSI concretes also require that an independent special (deputy) inspector observe the entire shotcrete placement process.  Structural engineers think that they are doing everyone a favory specifying sub-standard 2500 PSI concrete to avoid these additional quality assurance measures.

ACI 318-11 Durability Standards
As can be seen in the chart below, ACI 318-11, 4.2.1 specifies durability requirements for concrete (which includes shotcrete):


                  
Swimming pools by their very nature are always a Permeability Class P1.  They are always in contact with water where low permeability is required.

Corrosion protection for swimming pools more than likely fall into the Corrosion Classification C2, due to their exposure to both water and chlorides (this includes pools treated with chlorine, salt chlorinators or chlorine compounds).  ACI does not specify a MINIMUM level of chloride exposure, to require a C2 classification.  In any case, the C1 classification would be the absolute minimum level of corrosion protection required for swimming pools.

So swimming pools must meet the P1 and C1/C2 durability requirements.

Concrete Strengths for P1 & C1/C2 Classifications

It is clear from the following chart from ACI 318-11, 4.3.1, that swimming pool shotcrete should have a minimum strength of 4,000 PSI to satisfy Classification P1.
Classification C1 allows for the use of 2500 PSI concrete, while C2 requires the use of 5,000 PSI.
                                            

Therefore, swimming pools should be either 4,000 or 5,000 PSI, with 4,000 PSI being the ABSOLUTE MINIMUM STRENGTH.

Don't let your structural engineer do you any favors.  If there are any issues with the performance of the pool structure in the future, substandard concrete will come back to haunt everyone involved!

The Uniform Building Code, Uniform Swimming Pool and Spa Code and the California Building Codes all recognize the requirements of ACI 318.

Paolo Benedetti, SWD Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management 
Contact the author at: info@aquatictechnology.com or 408-776-8220 "Creating water as art."™ 
Aquatic Technology Pool and Spa© ©www.aquatictechnology.com 
All rights reserved.
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