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Package-pool builders and manufacturers are seeking to further blur the lines between vinyl-liner and concrete installations.

It’s a marked departure from the kit-pool mentality now that installers offer an endless variety of shapes and intricate features without affecting the pool’s performance or durability.

But constructing such specialty pools is no cakewalk.

Here, vinyl-liner veterans identify six trouble spots frequently encountered in the field, as well as tips for working through these traditional obstacles.

1. Compact and de-water the soil.

As vinyl-liner installations become more customized, builders are growing increasingly adventurous about grading around the pool.

But if done incorrectly, it can cause the vessel to move, resulting in leaks and other problems.

In fact, when homeowners ask the staff at Burton Pools and Spas to check out a troublesome pool built by another company, leaks are among the most common discoveries.

“Instead of bringing it down to natural grade, properly building it up or using some kind of retaining system to hold in the dirt, they’ll try to just pile dirt and then install the pool,” says Jesse Anderson, construction supervisor at the Fort Smith, Ark., firm, a Pool & Spa News Top Builder.

“Then, two to five years later, you’ve got major settlement,” he adds. “They’re just asking too much of [the ground] to support that weight.”

If you do build up the grade, be sure to properly compact the soil. Consult local codes, which may specify accepted compaction methods or rates. They also may tell you how large a layer, or lift, you can put down before compacting it with water or a tamper.

Some areas require a 95 percent compaction, which often must be verified through testing.

If the area has a high water table, you must find a way to divert the moisture away from the pool. Otherwise, water can build up behind the liner, causing it to float. Anderson recommends deciding how to do this when first surveying the site. It’s always a good idea to make gravity work for you, so figure out how to move the water downhill.

Locate a low point where the water can flow. Surface drains are less expensive and require minimal maintenance, whereas drain pipes must be watched because they tend to clog up.

Regardless of the system you use, just make sure you don’t direct water toward the house.

2. The liner must fit on custom pools.

On rectangular pools, there’s usually little worry that the liner will fit perfectly, and measuring is simple.

But free-forms, particularly the custom variety, can get complicated. When laying out the panels, you have to take many more measurements to plot various points on the curve.

“If you don’t do it right, you’re probably going to have problems with the liner fitting correctly — you will probably have wrinkles,” says Ron Fronheiser, president of Fronheiser Pools in Bally, Pa. “If the pool was supposed to be 14 feet wide at a given point, and it wound up being 13 feet, 8 inches, you would probably have wrinkling going on at that location.”

When measuring for the panels, don’t skip any steps. Take every measurement called for in the plans, and double-check each one before pouring the foundation.

If your measurements can’t be absolutely precise, make the measurements slightly larger. This way, the liner will still fit tightly. This is especially important on the slope between the shallow and deep ends. Otherwise, the slopes on the liner and floor won’t match up.

“If I have a break point on a pool that is supposed to be 15 feet [wide], I try to err on the side of being maybe 15 feet 1 inch, instead of 14 feet 10 inches,” Fronheiser says. “They actually make the liner a little bit smaller than the pool is.”

But don’t vary from the plans by more than an inch or two, he adds, or you risk overstretching the liner.

Burton Pools and Spas uses a different — but no less effective — method to ensure the panels and liner fit like gloves: The company’s crews combine the excavation and panel-setting steps.

“While we’re digging, we’ll be setting our panels and doing our measuring,” Anderson says. “If there’s a mistake, you find it a little faster because your panels are coming together and you see it.

“Then, before we pour our bond beam, we always double-check our measurements,” he adds.

3. Prevent leaking behind water-features and spas.

Special care must be taken when attaching another wet element, such as a waterfeature or spillover spa. As water spills into the pool, it has the potential to wick around and creep behind the liner.

Of course, always apply some kind of waterproofing membrane on the waterfeature structure itself. Also try at least one of the following methods:

  • Run a bead of silicone caulk along the joint between the liner and secondary vessel.
  • Place a drip edge on the underside of all weirs and spillways. To do this, make a saw-cut across the width, a couple of inches behind the edge of the weir or stone, creating a stopping point.

“When water gets to that point, it has a tendency to stop and drop off the edge of the rock instead of holding onto the bottom,” Anderson says.

Even if the volume is enough to sheer off the weir, cut the drip edge for those errant drops that wick back.

For additional waterproofing between the pool and waterfeature or spa footing, place a piece of 1/8-inch rubber liner on top of the pool-wall panel.

“We bolt that down and really caulk and silicone the whole joint where the panel and the rubber meet up,” says Tim Tindall, co-owner of Muskegon, Mich.-based Tindall Construction Inc. “Then we drape it [over the footing]. After finishing the stone and mortaring it in, we cut out the excess rubber.”

Now even water that might otherwise leak through the mortar joints will seep into the pool instead.

4. Use caution when backfilling radiused panels.

Once the panels are up, builders may struggle to pour foundations and backfill behind them without tipping the panels over.

“Sometimes if you backfill and don’t have enough supports inside, you might get a panel that bows in,” Tindall says.

Until the panels are equalized — with water inside and soil outside — they should be supported on the inside with the type of braces used to create concrete forms. (Note that these are different than the back braces provided by manufacturers.)

Rectangular pools are easy. Tindall and his company generally can finish a job with three to four supports on each side. But radiused panels are more likely to bow in or tip completely on their faces.

When backfilling behind these panels, use extra supports, including one at the center of the radius. Then backfill more slowly than you would with straight sides or hard corners. Don’t add more than a foot of soil at a time.

Compacting gravel helps: Because it self-compacts and self-levels, it will exert equal pressure as you add it.

5. Remember unique steps for coping.

More vinyl-liner pool builders are adding cantilever coping to their vessels to prevent them from looking like they came from kits. On such projects, builders must pay close attention to a couple of side issues.

First, be sure to match up the cantilever forms with the track. Both components must come from the same manufacturer or they won’t fit together properly.

“When you pour your concrete, it may slip out on you, it might push away, and then when you pull your form off, your concrete won’t be finished correctly,” Fronheiser says. “It’ll have a little bump out where it’ll be out past the wall of the pool. You can definitely see those things.”

Additionally, watch where you place joints on cantilever or stone coping. If possible, place a coping joint wherever two panels meet.

“Ideally, it should be placed right [over] a panel joint because that’s where the panels can move a little bit,” Tindall says.

6. Properly support waterfeatures.

Waterfeatures remain a fairly new vista for many vinyl-liner pool builders. So there’s still a learning curve.

Adding intricate and heavy rock waterfalls, for instance, requires installers to abandon the kit mentality that usually follows this type of construction.

One challenge in particular involves supporting the rock waterfall so that it doesn’t weigh down the wall panels. On such installations, contact the package-pool manufacturer first.

“Some of them have braces developed to handle a little more weight,” Anderson says. “As long as we know what we’re going to build and how much it’s going to weigh, a lot of the manufacturers we work with will let us know what we need to do.”

On especially heavy waterfeatures, some type of foundation is needed. The manufacturer may recommend pouring concrete piers using Sonotubes, or a more solid footing.

Some builders have found tried-and-true methods for supporting waterfeatures. Fronheiser’s company recently built a 10-foot stone waterfall with a vinyl-liner pool. His crew created a deep footing by pouring concrete in place of the normal backfill, behind the panels where the waterfeature would sit.

“We always pour a concrete footer at the base of our walls,” Fronheiser says. “In this particular case, we just brought the concrete right up to the top of the pool because we were handling so much weight. That’s pretty extreme. Typically, you don’t need to do that much. But we were putting huge boulders on this wall, and we wanted nothing to be able to settle there.”

When working in problematic soil, consult a local soils engineer. These professionals can better anticipate how much pressure expansive soil, for instance, will exert on the waterfall.


MORE INFORMATION

  • Around the Curves

Measuring free-form pools requires extra care.

  • Tight Control

Illustration of a drip edge for use on the underside of weirs and spillways.

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