- 1 Contracting Best Practices
- 2 Owner Build
- 3 Equipment Pad Best Practices
- 4 Trench to Equipment Pad
- 5 Gravel Use Around Pools
- 6 Soil Backfill and Compaction
- 7 Gunite Spa Design
- 8 Rebar and Gunite
- 9 Gunite Application
- 10 Watering New Gunite and Concrete
- 11 Proper Construction Techniques for Cantilevered Deck
- 12 Sequence of Tile, Coping, Deck for Plaster Pool
- 13 Travertine Quality and SWGs
- 14 Coping
- 15 Waterline Tile
- 16 Plaster Installation
- 17 Well Pit Pipe
- 18 Concrete Deck
- 19 Automatic Pool Cover
- 20 Fences
- 21 Inspections
Contracting Best Practices
Pool construction costs in the US typically range from $35,000 to $65,000. Many construction projects are very successful in terms of quality, cost and schedule while others fraught with problems. All construction projects can be impacted positively from best practices that have been developed and improved over the past 50 years.
One aspect of the best practices is the contracting process itself. Often prospective pool owners face as many challenges in this contracting process as they do in learning to care for their pool until they discover TFP methodology.
Contracting best practices are just as easy for the average pool owner as TFP pool care methodology. This post will document basic best practices in construction contracting as they apply to pool construction and pool renovation.
Develop Scope of Work
The first step in any project is to determine the appropriate scope of work. For pools this can be a lot of fun and a little frustrating. Here’s a good way to make it more fun:
- Start with a realistic amount you can afford
- Decide what the purpose is. Is this for the kids, adults, both? Lap-pool for exercise? Year-round, summer only? Budget driven – how much? This should be something you decide early since it will be important in making final decisions on scope
- Decide on your size and layout. There is software that can be useful just Google “pool design software”. Another good thing to do is to look at other pools in your neighborhood. What are the features you like and dislike? Start a post on TFP this site under pool constructions. You’ll get expert advice from people that are selling you nothing, but they get a kick out of helping you set the design specs for the best pool for you. A very rough estimate can be obtained using information at Home Advisor and other sites. You can also estimate at $100/sq ft. The exact price will only be known with a truly competitive bid from highly qualified contractors with a very well-defined scope of work
- You’ll be tempted to want to start talking to a pool builder, but you should resist until you’ve read this entire process and progressed to step 3. You’ll be in a much better position to engage with a pool builder after you know more about what you want and the contracting process itself. Then you’ll be taking them through a best practice bidding process. You should drive the process but unfortunately many are driving by the pool builder before the competition even starts.
- Inadequate scope definition is a prime cause of construction project failures. Make sure the following are decided BEFORE your bid documents are issued:
- Size, shape, depth and depth gradient
- Specify the depth of the pool every 2' along it's length so there are no disagreements later on slope. Regardless of what is said, there is no standard.
- Integrated Spa?
- Decking type (concrete, pavers, other)
- 2-speed or VS pump
- Filter type (sand, DE, cartridge0
- Controls (timer, automation, wifi?)
- Water Features
- Diving board or platform?
- Special Configurations like never-ending pool
- Pool Sub-Panel and capacity
- Pool finish type and color
- In pool features such as swim up table, sun table etc
- Rails, steps and ladders
- Site access limitations and obstructions
- Final grading and site completion requirements
Develop Bid Package
It is desirable to completely define the scope as soon as possible there are certain scope aspects that shouldn’t be finalized until after the bids are received. Hard scope are differentiated from soft scope in the bid documents. For example, the owner may decide they want a variable speed main pump. So this would be considered “hard scope” They may also prefer a manufacturer but want to see pricing for other manufacturers. So the bidders will have a pricing sheet that reflects this. One column lists all the required bid. Another will give the bidder an opportunity to provide a solicited alternate pump manufacturer. A starting point for the Scope of Work and Bid price sheet is given in Section 2. The final pricing sheet should reflect the owner’s preferences, soft scope, and hard scope.
Document Scope of Work and Pricing
The final step in scope development is to document it in tabular format. After all the decisions are made about scope, hard scope, preferences and solicited alternates there is one final decision. How do we want the pricing broken out? This is important if late changes are necessary since the more detailed the price break-down the easier it is to negotiate fair pricing for changes.
Successful bidding occurs when the following are accomplished:
- Scope of work is finalized and clearly documented
- Obligations of the contractor are clear and understood by both parties
- Obligations of the owner are clear and understood by both parties
- The best possible contractor is found and wins the bid.
Pool construction is complex and there are always some unpredictable events. When the points above are achieved there is a good foundation for cooperation of both parties and the outcome is always the best possible.
Cantilevers generally should only extend 1/3 of the overall length. If you want an 18" overhang then you'd need 36" completely supported behind it. The wider the ledge, the thicker it will need to be.
After talking with Pool Builders and General Contractors you may be tempted to become your own General Contractor in building your pool. Many people have successfully done this and even when using a Pool Builder many owners have found they needed to get involved in the construction to ensure it met their specifications and quality.
Building your own pool can save 10% to 30% or more over a builders costs. In some cases you can save a little bit and get a lot more for your money. Your key cost is your time and effort in planning the build, contracting the various work, getting permits and approvals, coordinating the timeline and build process, acquiring materials, coordinating inspections, and assuming liability for errors.
- Get a pool design and engineering
- Get bids and select contractors
- Complete layout, dig, and steel
- Plumbing rough in
- electrical rough in
- Water edge tile
- finish electrical
- finish plumbing
- Plaster/pebbletec finish
- Decking and coping
- Pool fill and initial startup
Pool Plans, Permits, and Inspections
As the General Contractor you will need to develop and manage the pool plans or hire someone to develop them. Pool plans are generally simple drawings. Your building department may look at your plans and make suggestions over the counter. Some municipalities require an engineers stamp on the pool plans you submit for review and approval.
Inquire at your local building department about the approvals, permits, and inspections that will be required.
You will be required to meet all all local building codes that apply to your property. Also check what HOA approvals may be needed if you live in a planned community.
Most builders subcontract for most, if not all, of the work to the same group of sub-contractors in an area. You can go direct to those contractors.
To find subcontractors in your area you can get on the phone and start making calls. See a pool company sign in the yard? Ask them who is doing their work and if you see a trade truck write down their number and go from there. Once you start calling you find the same names (good or bad) keep coming up. Make a detailed list.
Call the Gunite companies around your area. There usually aren't many, and ask three questions:
- Do you work with Owner Builds?
- What's your price?
- Do you recommend a steel company?
Once you get steel companies, the steel guys also do the layout and excavation. Ask them for a plumber and an electrician.
After that you need a deck, tile and plastering company, there are plenty around. Look for pool renovations, that's all they do, they will also do the startup.
Check that your sub-contractors have the necessary licenses for the scope of work they are doing. For example, plumbing and electrical connections. Also check that the sub-contractors meet your personal requirements for insurance and workman's compensation coverage.
Communication with sub-contractors can a bit of an issue if you don't speak their language such as Spanish.
Establishing a payment schedule for each subcontractor is part of the price negotiations. In general a small down payment and progress payments based on completion of specific milestones limits your risk of a contractor having your money and not completing his work.
Consider obtaining a lien release with all payments made to contractors. The lien release essentially says that the contractor or supplier has been paid for his, her or its services and waives the right to file a mechanic's lien against the property.
The big 3 pool equipment manufacturers - Pentair, Hayward, and Jandy - have all restricted some or all of their equipment through the Internet. Some have models of equipment that is only sold by pool stores. Others have limited the warranty on equipment not installed by pool builders or "professional installers." This area is constantly changing and you need to look at the availability and warranty on the equipment you are considering.
While equipment may not be available on the Internet to click to buy, or have limited warranty if purchased that way, there are pool stores who sell pool equipment at discounts over the phone that can qualify for full warranties if installed following manufactures requirements.
Owner Build Resources
Equipment Pad Best Practices
Trench to Equipment Pad
18" deep minimum. You can start at the level the pipes come out of the pool, then 90 up to the 18" depth. The width should be wide enough that all the suction and return lines can lay horizontally side by side. If you have a spa or water features, the number of lines can add up quickly. A 36"-48" wide trench is not uncommon. A simple pool can be 12" wide.
Placing 2" of clean sand above and below the plumbing will help to protect the pipes.
Gravel Use Around Pools
Soil Backfill and Compaction
When soil is excavated it is fluffed up and aerated. If you just dump it back in the excavation it leaves a massive amount of air space in the soil. Over time the soil will compress and fill the air pockets (settle). This can take many years depending on the soil type and how much moisture is introduced to the area.
The proper way to place soil back in any excavation is to compact it in lifts. This means putting in a maximum of 12" of soil then running a compactor over it which Is rated for that depth of lift and soil type. Then place the next 12" in and rinse and repeat until you get to the top. The compactor compresses the soil to get the air pockets out.
Pools should be placed on virgin soil, never dug soil that was compacted. If areas are overdug they should be filled with the appropriate gravel.
When a Pool Builder dumps dirt for backfill in an area where a concrete deck is planned and they expect the concrete to span over any settling that may occur, the concrete will span settled areas for a while but it will not last. Long term it will be much cheaper and easier to do it right from the start with the proper compaction and gravel. You don't want to be looking at cracks or puddles in a few years
Gunite Spa Design
See Gunite Spas
Rebar and Gunite
Concrete swimming pools are structures and, therefore, by code, require structural engineering. The exact rebar specifications should be designed by a structural engineer for a project.
Without getting into specifics, there is usually a range of specifications for things like rebar size, spacing of the rebar, concrete thickness, concrete strength, etc. At the lower end, the idea is to save money on construction. It is usually worthwhile to go above the minimum to help minimize long term problems.
It is best to inquire about the range of specifications, the cost differences, and the strength differences so that you can make an informed decision.
If you want to know what the specifications of the plans are, ask for a copy of the drawings and discuss them with the PB or the engineer. However if you disagree with the drawing, then you should probably be ready to scientifically / mathematically state your case about why you disagree and which building standard or municipal building code section your objection is covered under.
Try to refrain from requesting that x amount of rebar of your choosing be spaced at y distance. You will only alienate both the PB and Engineer with frivolous requests.
If the soil is an issue, you should get a geotechnical engineer to evaluate and advise. You may need piers if the soil is not considered stable.
It's always best to have an engineer design a plan for your specific project. Using "standard" designs only works for nominally standard projects.
Pool Shell Design
The swimming pool is designed to withstand the forces exerted on the walls and floor by the water which will be in the pool. There are many factors to consider in determining how the wall should be built in order to support the load placed on it.
The size of the rebar, the slump of the concrete, the location of the rebar, the spacing of the rebar the size and grade of the rebar are placed in the pool so it is structurally sound. So it's entirely possible, and even likely, that any given pool will have an assortment of rebar at different spacings. Water exerts a known amount of pressure upon a pool structure and the structure will be designed to withstand that force.
There are special considerations in design if the pool is being built in difficult soils, on a slope, or in earthquake zones.
This is why concrete/ gunite pools are typically designed by an engineer and must meet the structural building codes of your municipality. Also, ANSI has minimum standards that a gunite pool should be contructed to.
After the building plans have been drawn and have all sorts of specifications and info included it's reviewed by an engineer in the building permit department, a building permit is issued if it meets the building code for structural, hydraulic and electrics. The building code guy is there to protect you, and as much of a PITA they can sometimes be, they generally do a good job of protecting us from ourselves as well as keeping our towns and neighborhoods safe from things that could make our lives miserable in the long run.
In many parts of the country, builders already know if the soil is clay, loam, sand, rock, or whatever the case is, and generally how stable it is, and what the water table is. People in the business usually skip a geo-survey and just go ahead and design the pool based upon geographically known conditions and a knowledge base of experience from prior projects.
A soil engineer may need to be involved if you are building on a slope or in an area that has been filled as part of prior construction.
Typical Rebar & Gunite Specifications
- Rebar - #4, grade 60 on 9" to 12' centers
- Number 3 rebar is 3/8 thick and number 4 is 4/8 thick.
- Some builders use number three and some use number four and some that use number 3 beef up the steel in certain places with number 4.
- While rebar can be helpful, tight spacing and big diameter can increase "shadowing", which is where concrete does not get behind the rebar properly and creates weak spots. That is why number 5 rebar is the maximum to be used on pool shells.
- Concrete, 8" to 9" thickness with a strength of 5,000 psi
- Generally speaking, concrete walls are about 8 inches thick and the floor is 6 inches thick. This assumes the soil it's being built on is stable and not located in an earthquake zone.
Role of the Rebar
Rebar is reinforced steel poles.
Rebar supports the concrete which would move or break if set against the soil without rebar. Rebar doesn't really prevent cracking unless rebar is prestressed because rebar doesn't really begin to help until it's under tension.
Rebar will help reduce the size of cracks and reduce the separation of the concrete either opening or shear sliding.
Gunite or Shotcrete
All things considered in a swimming pool, either option will produce a strong shell. The skill and knowledge of the applicator and crew will far supersede any negligible differences between the two.
Shotcrete has the advantage of having larger aggregate in the mix and the yields are typically higher in compressive strength given the same precured cement content. Some may also argue that more pneumatic force can be applied to Shotcrete during application yet produce much less rebound.
Shotcrete can be ordered with the cement, aggregate, and water content (slump) specified which are then measured by a computer and generate a ticket that shows each of those parameters and the batch mix time so you know how long it's been in the truck. On very hot days, plasticizers can be added to replace/reduce the water needed for application without decreasing the ultimate cured strength.
Gunite is much different. It is preferred to have the mix brought dry in a cement truck for the same reasons mentioned above but not all contractors do this. Contrators can dump sand in the street and shuttle it to their equipment with a skip loader where it is then mixed with cement and carried to the nozzle by compressed air. In this scenario the cement/sand ratio is nothing more than an approximate, as is the water/cement ratio as the nozzle applicator controls it basically by sight. The finishers prefer a wetter mix because it's easier to trowel and smooth but this yields a much weaker product that is prone to shrinkage cracks and reduced compressive strength.
Gunite produces significantly more rebound which should be discarded but is rarely done. The rebound is often used in steps and stairs where it will end up causing problems down the road.
Cold joints in shotcrete (gunite) are in some ways a myth. Laboratory testing has shown that multiple layer shotcrete has no anisotropic weakness (cold joint) when the layers are applied within 7 days of each other. In the real world a plane of weakness often develops between layers, but it's almost always due to improper surface prep. Dust, dirt, and rebound from shooting adjacent areas will accumulate on the first layer during/after the shoot, and if not thoroughly removed prior to applying the next layer a plane of weakness will develop. If the first layer is troweled smooth it can also impede bonding of the second layer. If too much time passes between layers a cold joint is possible, but in that case the reduction in strength is pretty minimal as long as the surface is properly prepped.
Gunite Over Multiple Days
The pool shell can be poured over multiple days. There will not be a cold joint if they prepare the unfinished edge correctly. This is common on very large pools and commercial projects since you simply cannot shoot enough gunite in one day.
Watering New Gunite and Concrete
Proper Construction Techniques for Cantilevered Deck
Sequence of Tile, Coping, Deck for Plaster Pool
The consensus seems to be to do tile, then coping then deck although it can vary with the shape, materials, and contractor preference.
Simple logic is you always build from the bottom up not the top down. In a pool you want the tile to set perfectly level so the water line looks correct all the way around the pool. If the coping is set unlevel then they need to adjust the tile and the seam in between the tile and coping will not be uniform and basically throw the whole tile install off.
It can be done either way however if you ask the actual installers most of them would prefer the tile first then coping.
Here are some things to consider:
- Do the tile before coping on gunite pools.
- The coping will set the elevation for everything else around it.
- A professional should be able to take one tile/piece and figure out the measurements.
- You want everything to drain away from the pool therefore you should start at the pool.
- With natural stone coping you lay it first. Don't let anyone tell you otherwise.
- You cannot make demo saw cuts to round the backside for curves with concrete in the way. It can be done but it is not by choice and way more work.
- Coping thickness and setting bed thickness varies. You let the coping set the elevation and work from there.
- You want 1/8" pitch away from pool in all directions and plan ahead for drainage
- Why would you want the coping crew to work on top of your nice finished concrete deck if you don't have to?
- They could lay down a protective layer of some kind, but they probably won't.
Travertine Quality and SWGs
Well Pit Pipe
- going down to depth of pool is the best way
- make hole twice the size of pipe
- 24-30" hole for 13" pipe
- use woven heavy septic fabric
- hang strips of filter fabric down the sides of the hole
- perforate the pipe with a drill to a foot below the top of fabric
- zip-tie fabric to the pipe
- place pipe in the middle of hole
- add some more stone a few inches up then backfill
- backfill with clean 3/4 stone
- pipe the discharge and electric underground
- put a skimmer lid on it or an end cap depending where it is
- While a sand or gravel base is not needed it is helpful over clay. At the very least you want to make sure the subgrade has been compacted.
- Removal and replacement of highly expansive or unstable soil. Fill has to be properly compacted.
- Installation of a 6 inch gravel base to minimize vertical movement from moisture variations in the subbase and frost heaving.
- "Typical" rebar spacing for deck/sidewalk is #3 (3/8" rebar) at 18" spacing. You also see a lot of welded wire fabric for residential sidewalks but don't settle for that in the decking. *Fibermesh (small fiberglass fibers in the concrete) should just be used as a compliment to the rebar and not as a substitute.
- Prior to the pour, water the subbase just short of puddling the water.
- Use 3500 psi fiber reinforced concrete @ a 4.5 inch slump and 6% air. Never exceed a 5 inch slump as this is by far the largest cause of concrete cracking
- Consolidate the concrete with a jitterbug or vibrating screed.
- Bull float and hand float the slab. Never use wood floats on air entrained concrete. Tool or install contraction control joints at this time. These should be a maximum spacing of 2 times the width of the slab or 12 feet apart which ever is less.
- Control joints (either sawed or tooled) will give the concrete a weakened point to crack. Sawed joints give a cleaner look
- Wait until the concrete slakes or skins over before finishing with a magnesium float and steel trowel. Attempting to finish prior to slaking will just lead to overworking the surface. Never splash water on the surface to aid in troweling.
- If you are pouring against coping or existing concrete (foundation, sidewalk, garage, etc) you will also need expansion joints. These are typically black fiber board or redwood. The expansion joints have some compression give and will allow the concrete to expand and contract against to prevent cracking and movement.
- When it is time to install try to have them pour before noon before it gets to hot and they have to add more water to keep the concrete workable (which could result in small hairline shrinkage cracks). If possible, check the time on the concrete ticket to see how long the truck has been on the road, more than an hour is unacceptable and grounds to reject the load. The longer it has been on the road the more water will have been added to it.
- Protect the finished concrete from severe temperature swings or dehumidifying conditions such as wind, sun, hot or dry ambient air conditions etc. with plastic, burlap, concrete blankets, sealer etc. Do not use plastic on dyed concrete. As Henry said, you want it to chemically cure, not dry.
Concrete can expand and contract as much as 3/4 inch over a 100 ft distance with a temperature swing of 40 degrees. With this in mind you can determine placement of expansion joints and control joints.
Expansion joints are the full depth of the slab and should be placed against other foundations such as the pool bond beam and coping, house foundations or abutting slabs. On a rectangle pool you should use expansion joints where slabs are perpendicular. On a continuous run they should a maximum of 48 ft apart.
Control joints aid in preventing shrinkage and contraction cracks and should be a minimum of 25% the depth of the slab and located as previously mentioned.
Automatic Pool Cover
Some factors to consider in the design:
- A cover well that is designed with good drainage and easy access so that the cover can be rinsed as-needed and no stagnant water can build up.
- Connecting the track to the pools bonding wire system. If the track is aluminum then you should have an additional wire attaching it to a magnesium anode buried in moist soil. If your soil is heavy clay or dries out quickly, then the anode should be bagged in a cotton bag with an appropriate media mix to surround it and retain moisture. You could also install a drip irrigation emitter nearby or locate the anode near a sprinkler so that the soil stays moist. Copper wire (unsheathed bonding wire is fine) should be used to make the connection.
- If the track is to be screwed into the coping or fastened with screws, the fasteners should be nonferrous (aluminum) or a corrosion resistant stainless steel.
Automatic Pool Cover with a SWG
You need to look at the specifics of the auto-cover design. Most are aluminum tracks which can be susceptible to corrosion from the higher chloride concentrations found in SWG pools. All chlorine pools will have higher chloride concentration (disinfecting chlorine breaks down into chloride ion) but SWG pools start with a higher overall level (typically around 3200ppm versus < 1000ppm for traditionally chlorinated pools with winter/rain dilution).
Find out who the manufacturer of the auto-cover is and call them to see what they recommend. There may be specific installation requirements for the track and cover well that need to be in place for an SWG pool.
See Safety Fence.
Most areas require several inspections performed during pool construction for rebar, plumbing, electrical, bonding, etc.
Checking the rebar before the gunite is applied is one of those inspections.
Final inspections can include:
- fence height
- bonding grid
- gas/electrical connections
- soil/hill shoring up
Its always good idea for you to be there during the inspections in case you have any observations, concerns, or questions. The inspector should be able to ease your mind about them.