Category Archives: Construction

Difference in Commercial and Residential Swimming Pool Design Construction

Having been involved in the commercial swimming pool industry for over 20 years, I’ve been fortunate to be a part of the planning and design of hundreds of aquatic facilities across the globe.  During this time, I’ve seen my fair share of the good, the bad and yes even the ugly.  For years my head has been ingrained with industry best practices and design standards specific to the commercial pool world.  Therefore, it should have come as no surprise that when I recently made the decision to make my family happy by investing in our very first backyard pool, I was amazed where my involvement was very similar as well as completely divergent from my commercial pool experiences.

Home Pool Fun!

First, let’s start with the similarities that are common for both commercial and residential pool design and construction. The two most obvious being the basic principal of containing and treating water for that can be use humans for recreation, fitness, training and a host of other activities.   One of the most important principals of swimming pool design is having a structure that can contain water with little to no water loss.  Whether it be concrete, pre-engineered steel panels, fiberglass, vinyl lined or other materials for construction, the structure must contain water.  Once we have a structure that can accomplish this, there must be a method of continuous water treatment. As humans immerse themselves within this water containing structure, there is a need to continually treat the organic loading that will occur.  Sweat, skin, urea, lotions, etc. are continually be added to the water which create a prime breeding ground for potential recreational water illnesses.  And for most residential pools, there’s of course the occasional dip in the pool by the family dog!  Fortunately, science and technology provide the ability to control these pathogens through filtration and chemical treatment.  It’s also worth mentioning that the day to day operations of swimming pools can greatly impact the success of pool water treatment but I’ll save that conversation for another time.

Moving beyond the obvious principals of water containment and treatment, there becomes numerous best practices, or industry standards where differences can be found.  Before I get into these items, it’s worth noting that a majority of these difference are for good reason.  Obviously, the size, use and bather loading of a commercial pool is typically far greater than that of a residential pool.  For that reason alone, the size and complexity of pool equipment that is used in a residential pool system is often to a lesser degree from that of their commercial counterparts.  Regardless of the size of a pool, there were several aspects I observed when dealing with a residential pool project as compared to commercial.  And while I could spend hours discussing the technical aspects of swimming pool design ranging from hydraulics to finishes, I’ll leave the technical jargon for a future discussion.  

Having lead commercial pool design projects for over two decades, I found there to be a significant difference in the level of detail and information that is required on a residential pool set of drawings.  A residential pool project is almost always done under a design-build delivery method and this means the installing contractor is typically responsible for their own design.  As a result, there often becomes a far greater expectation that means and methods will take a much stronger role in determining the detail in plans and written specifications.  Additionally, the review process for plans and specifications in the commercial pool environment requires plans to be very comprehensive in their development.  Because of this reason alone, there is little room for questioning how things will come together in the field on a commercial pool project.  My recommendation for any person who is going to invest in a residential pool is to always review your pool plans and do not be afraid to ask questions.  If you observe gaps in the plans or the information provided appears to be incomplete and lack clarity, don’t be afraid to ask your contactor for more detail.  Any good residential pool contactor should be happy to oblige in answering your questions.  If your contractor has difficulty in answering your questions, or is responding with vague responses, there is reason to be concerned.

Let’s now turn our discussion to budget.  I’ve often found individuals who have invested in a residential pool may one day find themselves representing their community in a commercial pool project.  These individuals can initially experience shock when the discussion turns to budget, as they automatically assume the investment made for their backyard pool will be comparable to that of a commercial pool.  In most cases, commercial pool construction typically requires a higher cost per square foot (SF) of pool surface area as compared to the residential pool market.  In fact, it can be expected that cost per SF for a commercial pool may be 2 to even 3 times that of a residential installation.  Primary drivers of this cost discrepancy can be attributed to wide array of items.  These may include structural and hydraulic design materials and solutions, as well as the supporting mechanical, filtration and chemical treatment systems.  Additionally, most residential pools have maximum pool depth of 7 to 9 feet resulting in less overall all materials for construction when installing a commercial pool that may include areas where the pool depth is 12 to 13 feet deep to support springboard diving equipment.

A most intriguing part of my backyard pool experience was communication.  I’ve already mentioned that asking questions is important.  However, what I found to be interesting is the difference in the degree of communication.  Often a residential pool builder will rarely deal with a client that has a deep understanding of the design and construction of swimming pools.  While it may seem obvious that when questions aren’t asked, answers aren’t provided, often the residential pool owner does not even know where to begin.  As compared to a commercial pool project that will almost certainly involve design professionals in some capacity, these professionals are tasked to ensure the project is delivered on-time, on-budget and built to a strict set of guidelines.  Even under a commercial pool design-build delivery process, there will be professional architects and engineers that generally have some say in the project outcomes.  As a result my experiences in the commercial pool industry have been that the design process is very communicative and detailed.  This micro approach then carries into the construction where design professionals provide observations in the field which are carefully documented through written reports.  When the contractor experiences questions in the field these are documented by written Requests for Information (RFI) requiring a thorough and written response.  The cadence of this communication as well as construction in the commercial pool world is often more intense as well.  Experiencing my own backyard pool installation, I found that communication was sporadic at best.  This is not to say my contactor didn’t care, but when the Owner is not asking questions, the perception will be all is well.  Often when I requested to have a conversation or shared my observations, I found that my residential pool builder was more than happy to discuss things with me.

Overall, the experience of having a pool built at my personal residence was exciting but certainly not without a few ups and downs.  Upon completion I found my residential pool builder to be very knowledgeable and wanted to leave the project with a happy customer.   Never forget that the only bad question is the question not asked.

My Finished View!

A Few Technical Tips for Your Residential Pool Project

  • Request that a licensed professional engineer sign and seal the pool drawings.  This includes all structural design calculations.
  • Make sure the swimming pool design has taken into consideration all geotechnical conditions.
  • Ensure that all pool piping will be pressure tested to ensure water tightness.
  • Pool piping should be Schedule 40 or Schedule 80 PVC.
  • Install a VFD on your pool recirculation pump as an energy savings measure.
  • All metallic embeds should be bonded and grounded.
  • When located in a geographic location that will require closing your pool in the winter months, ensure that proper winterization of the pool and pool systems has been completed.
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Surge Tanks

A surge tank is a water containing vessel that takes water from a swimming pool perimeter gutter system. Swimmers create waves when they enter a pool, compete, swim laps, exercise or just play. The perimeter gutter system captures these waves, or surge of water, so that they do not rebound back into the pool. A perimeter gutter and surge tank system are important in that they assist competition pool water, or any pool with a gutter system, return to a quiescent state which is a faster pool. Competition or training pools that do not utilize a gutter and surge tank system are slower and antiquated.

Surge tanks are typically constructed of concrete and located in the filter room or under the pool deck adjacent to the swimming pool. Cast-in-place concrete allows the swimming pool designer to size the surge tank as needed to fit the site conditions. Pre-cast surge tanks can be used as well but the dimensions tend to be less flexible. The surge tank size depends upon the surface area of the swimming pool. Most local and state health codes require one (1) gallon of surge capacity for every one (1) sq ft of pool surface area. Only a few health codes require two (2) gallons of surge capacity for every one (1) sq ft of pool surface area. This should be confirmed with local or state health department regulations.

There is a lot going on inside a surge tank. Piping from the perimeter gutter to the surge tank enters at several locations. The number of gutter dropouts depends on the size of the pool. Main re-circulation piping pulls water from the surge tank to the re-circulation pump and filter system before it is chemically treated and returned to the pool. Special consideration is also needed for maintaining atmospheric pressure inside the vessel. Typically, an air relief vent pipe is satisfactory for maintaining this equalization. However, the vent line should be routed independently to atmosphere to ensure that noxious fumes and vapors from the surge tank are not introduced into the filter room or natatorium. A water level controller should be installed in the surge tank as well to monitor the water level and automatically activate the automatic water make up control valve should the water level drop below design levels. An access hatch is always required to access the interior of the surge tank for cleaning and routine maintenance. When surge tanks are constructed under the pool deck adjacent to the pool, they are usually placed next to the deep end of the pool. This approach saves on construction cost as one wall is common with the pool.
Surge tanks are installed on the fastest swimming pools in the world including Olympic Venues, Universities, High Schools, Elementary Schools and Municipal Aquatic Facilities. If your aquatic facility has a competitive pool, training pool or lap pool and a fast pool is desired then you will want a perimeter gutter system complete with a surge tank.

Swimming Pool Gutters

Perimeter overflow systems are a critical part of any swimming pool. There are two main types of perimeter overflow systems; skimmers and gutters. Skimmers are often times the more simplistic and less expensive options as they are traditionally used for back yard or leisure-style pools. Gutters, however, can be used on any pool type and they can be constructed in an array of different shapes and sizes. Depending on the intended use for the pool, some gutters are better suited than others. The following will discuss the pros and cons of the four most common styles of gutters: deck level, fully recessed, roll-out, and parapet.

Deck Level Gutter

The deck level or “rim flow” overflow system features a gutter lip 1” above the elevation of the pool deck. This design enables even the weakest swimmer to egress with little effort over the water’s edge. This is often the most desirable gutter for the recreational and instructional swimmer. Program heavy natatoriums, where many classes are taught, often choose this design option. Deck level gutters are the least expensive gutter option as they require less concrete and forming compared to some of the other options.

The deck level gutter does not have back curb, therefore, water has the potential to “run” across the gutter grating or splash-out resulting in a wet pool deck. Because the water level in the pool is typically at or above the elevation of the adjacent perimeter slabs, surge tanks often will need to be fitted with overflow piping to prevent flooding.

Fully Recessed Gutter

Competitive swimmers and coaches prefer this design. The pool deck cantilevers over the gutter trough. The top of deck is approximately 12” above the water. The overhang provides the competitive swimmer with a visual reference plane for the underwater wall. The recessed gutter very effectively captures the wave amplitude and keeps the pool decks relatively dry. The disadvantage is that the high overhang makes egress from the pool rather difficult, and as a result, most people choose to use one of the pool ladders. This option is often used for natatoriums where competitive swimming is the predominant programmed activity. It should be noted, however, that fully recessed gutters are typically one of the most expensive gutter options.

Roll-Out Gutter

The roll-out gutter profile combines the features of the fully recessed and deck level configurations. It consists of a gutter lip and grate at the water level. The deck, approximately 5” above the water surface, forms a curb at the rear of the gutter grate. This curb contains much of the wave action and keeps the pool deck relatively free from water escaping the gutter assembly. The low configuration at the water’s edge still allows swimmers to egress easily. Unlike the fully recessed gutter however, the roll-out gutter does not provide competitive swimmers with a visual reference of the end wall above the water surface.

Roll-out Gutter with Parapet

A roll-gutter with parapet combines the roll-out gutter design on the sides of the pool with a parapet on the ends of  the pool. The parapet is very similar to the fully recessed gutter option with a 12” water to deck dimension and a visual reference plane for the underwater wall. The parapet utilizes a 6” curb from the pool deck to top of the gutter where the starting blocks would typically be located. This option is often times used when lap swimming is the primary use, but the pool is also used for other programming activities.

Other Tile Color Options

When discussing pools or water features most people associate them with the color, blue.  Water represents a refreshing, even relaxing or cool feeling of renewal.  This association is one reason why most pools and features contain primarily blue tile finishes or accents.  Nothing is wrong with blue, but in the world of tile there are so many other options that can be explored!

In today’s design, people are wanting something different – Different color palettes, different textures, different shapes, different styles, etc.  The goal is to have their pool or feature stand out and be something unique.   The great thing is, that goal can be achieved!  Pool tile options have expanded well beyond that of the traditional glazed blues and blacks.

When a School, University, Community Center or any other facility would like to carry their “colors” throughout a building this can now include the pool.  The tile industry has increased the color offerings and materials that are applicable to pool installations.  Tile can be a single solid color, speckled, swirled, patterned, clear, iridescent, etc.   One of the other trends in tile is the natural stone-look that can be integrated into the pool.  Several manufacturers have introduced specific tile product series addressing this appearance with color ranges from the white/tans to the greys/black.  The tiles surface texture replicates actual stone and enhances the theme of naturalistic pools.

 

Tiles today are offered in several different sizes and shapes within one pattern as well as offering a variety of color blends.  Colors from reds, greys, whites, greens, beiges, tans and many more can be designed into a pool interior and even be utilized on pool decks.  The possibilities are endless….

 

Thermoplastic Pipe Expansion

Swimming pool piping is design is notorious for including long straight runs of pipe.  For pools that do include long runs of straight pipe sections, consideration may be given to the use of expansion loops or mechanical expansion joints to accommodate thermal expansion and contraction.  The ASTM Standard 2774 references “Underground Installation of Thermoplastic Pressure Piping”. This ASTM Standard 2774 contains specific information on the topic of expansion in pool piping.  Expansion and contraction of thermoplastic pipe is typically due to temperature changes to either the surrounding pipe embedment materials or changes in the pool water traveling in the pipe system. When temperature changes of the thermoplastic pipe does occur, changes to the piping network in the form of elongation or contraction will occur.  Therefore, in piping networks where there may exist sections of the pipe that are straight and without bends, expansion and contraction of the pipe can cause failures in the system.  Swimming pool piping networks that include PVC pipe used in straight runs nearing 100 LF should take special consideration to the potential expansion and contraction of the pool pipe.  In these instances the design of the pool piping system should have the coefficient of expansion calculated for determination if design accommodations for the expansion and contraction should be included.

In cases where expansion and contraction will be significant, inclusion of an expansion loop or even a mechanical expansion joint can be installed.  A pipe loop is a relatively easy item to include within the piping network.   This pipe loop, or offset, can alleviate the bending stresses that can occur when thermoplastic piping systems experience expansion and contraction.  If expansion joints are required, a detail for the expansion loop may include a specific dimension for the offset lengths.  Mechanical expansion joints work like a piston allowing the pipe to elongate or contract within the pipe run.  The installation of mechanical expansion and contraction joints is critical, particularly cleaning debris (sand, rock, dirt) out of the moving parts.  If small particles come in contact with the mechanical joint mechanism the joints seal can become compromised.

In most instances a linear pipe runs without interruption of bends, joints or pipe size changes is not common.  However, in situations where conditions do allow long pipe runs, your design should pay special attention for need of expansion and contraction loops and mechanical joints.