Tips for measuring and installing covers on challenging pools

January 1, 2011

With the proper measurements, a safety cover can be designed to look and fit great on any pool, no matter the shape or size.

By J. Kevin Shea

Today’s swimming pools are beautiful—adorned with raised spas, waterfalls and vanishing edges, not to mention exotic caves and bridges. However, as intricate as these may be, at the end of the swimming season, pool professionals are left with the challenging task of measuring and installing safety covers to keep these outdoor environments safe and free of debris, not to mention esthetically pleasing in the backyard.

Safety cover manufacturers are like tailors and fabricating them can be likened to making a suit—with the proper measurements a safety cover can be designed to look and fit great on any pool.

There are many challenges to measuring and installing safety covers on complicated poolscapes, but pool professionals can succeed by following some simple rules and ‘tricks of the trade’ used by seasoned installers.

Measuring: It’s all in the details

Measuring the pool and surrounding obstacles is the primary concern when measuring for a safety cover—especially on a pool that has never had one.

Installers must provide the safety cover manufacturer with a detailed description and accurate measurements of the pool’s perimeter. Before providing the manufacturer with any dimensions, the installer must first check to make sure the pool is ‘square,’ as this could affect the cover’s design (e.g. strap placement) and proper fit.

If the safety cover is for a vinyl pool where the liner was recently replaced, the installer is already one step ahead, as the perimeter measurements should already be on file.

Measure the perimeter

Measuring the perimeter of a pool is a fairly simple process for rectangle, Grecian and oval-shaped pools. However, when dealing with kidney-shaped or freeform pools, a surveying technique called ‘triangulation’ should be employed to obtain perimeter dimensions. With this technique, the area is divided into triangles (one being the baseline) to determine the distance between any two points.

It is also a good idea to use the manufacturer’s safety cover measurement forms and have them on hand at the project site. This helps ensure all the necessary measurements are recorded and eliminates the need to return to the job site because a key measurement was missed.

When dealing with kidney-shaped or freeform pools, a surveying technique called ‘triangulation’ should be employed to obtain the pool’s perimeter dimensions.

Before recording the ‘A-B’ triangulation measurements, be sure both points are exact. If they are off even by 25 mm (1 in.), every measurement in the project will be inaccurate. To avoid this, use well-secured surveying stakes when taking measurements.

“Not only do the plotting pins have to remain secure while you are measuring, they need to remain secure until you have the cover installed,” explains Jeff Knapp from the Pool Doctor in Anniston, Ala., who returns to the job site at least once after providing the initial measurements to the safety cover manufacturer.

“I plan this into my pricing,” he says. “But this makes it all the more important that my stakes are still perfectly secured and my numbered points are still visible, as it allows me to check the measurements I originally provided.”

Knapp uses street chalk to make sure his numbered points can be checked later on.

“I use the type (chalk) kids use; it’s perfect for numbering all of the points around the pool when taking dimensions.”

Gary Tripp from Tripp Construction in Raymore, Mo., agrees, but has found he measures for safety covers on a lot of decks that are too nice to mark up.

“I get nervous when labelling my points on expensive stone that might be easily stained, so I keep blue painter’s tape in my bag of measuring tools,” he says. Tripp labels each point on the tape and leaves it in place so he can refer to the points even when installing the cover.

Note all obstacles

When measuring, it is important to document any obstacles around the pool’s perimeter, including decorative rocks, plants, planters, minimal/limited deck, raised spas, walls, etc.

Each obstacle should be measured using the triangulation method and include ‘numbered points.’ Taking photos of the entire poolscape and sending them in with the dimensions is a great way to ensure nothing is missed.

When measuring, it is important to document any obstacles around the pool’s perimeter. Some covers have several cut outs for ladders, as getting a cover to fit snuggly around a stainless steel tube can be a challenge.

“I start my measuring jobs with my digital camera,” Knapp says. “I take photos of everything around the pool where the cover is to be installed—from far away and close up. A picture is worth a thousand words; if you don’t have a digital camera, get one. It’s a small price to pay versus the costs associated with getting a safety cover that doesn’t fit properly.”

Some safety cover manufacturers offer plotting software that can be loaded onto a laptop, allowing pool professionals to utilize the program on the job site. For example, pool perimeter dimensions can be entered into the program, as measurements are being taken, to allow the technician to verify the measurements as a plotted shape. These programs can also save a pool professional the trouble of having to return to the job site to confirm measurements, saving valuable time.

Ladders, slides and diving boards can present some of the most challenging obstacles to work around. For example, non-removable ladders that are set into the concrete deck or slides and diving boards that protrude extensively into the pool area can be quite difficult to measure. Some covers have several cut outs for ladders, as getting a cover to fit snuggly around a stainless steel tube can be a challenge.

Measure vanishing edges

Measuring a pool with a vanishing edge can present a few challenges; however, it is by no means impossible. On these pools, the safety cover is generally fastened to the vertical wall behind the vanishing edge; in some cases, the collection trough may also need to be covered. Either way, to plot the points along the vanishing edge properly it is important to lower the water level and turn off the pump. Always be sure there is a point at the beginning and end of the edge.

To avoid any problems, simply explain to the homeowner what needs to be done to properly measure the pool’s perimeter and that the process will take roughly an hour to perform.

Measuring replacement safety covers

Now that safety covers have been available for many years and more prevalent the last two decades, many installers have seen a huge increase in demand for replacement covers (most covers last approximately 10 years).

Homeowners are not interested in having additional holes drilled into their deck, so on top of plotting the pool’s perimeter, installers must also plot the existing anchor points in the deck.

Plotting the existing anchors is very important, as not all safety covers are manufactured the same. For example, some have 1.5- x 1.5-m (5- x 5-ft) sections between the straps, while others use 1- x 1-m (3- x 3-ft) sections. Varying amounts of ‘overlap’ may exist between manufacturers as well. Overlap normally ranges from 0.3 to 0.45 m (12 to 18 in.) adding an additional 0.6 to 1 m (2 to 3 ft) to the overall cover size versus the actual pool.

The most common mistake installers make when plotting a replacement cover is taking the measurements from ‘between’ the straps on the old safety cover. This will provide an inaccurate measurement of the safety covers total length.

The proper way to obtain this measurement is to start at the end strap (the perimeter strap that forms the end of a rectangular cover), and measure to the first strap. Then, once again from the end strap, measure to the second strap, and so on. By starting from the end strap each time, the installer will be sure to get an accurate length of the cover.

On freeform shaped pool covers, the end strap is identified as the very first strap that extends across the pool from anchor to anchor. When measuring for these covers, be sure to account for the spacing between the longest length of the pool/cover and the first cross strap, as well as the spacing across the width of the pool, as they are often not symmetrical squares or grids. It is also important to note what end of the pool the measurements started from (e.g. shallow end or deep end) in order to establish the pool’s right and left sides.

Installation: It’s all about positioning

Before drilling any holes in the deck, it is important to lay the cover over the pool first to position it correctly. Some installers use sandbags to hold the cover in place, while others use cinder blocks. If using cinder blocks, place something on the cover to protect it from damage.

When placing the safety cover, start with the ‘critical’ parts (e.g. around obstacles such as slides, diving boards and stairs). Make sure all cut outs are lined up perfectly, then adjust around the perimeter of the pool.

Tethering ropes across the entire width and length of the pool to set the cover on top is an easy way to ensure the cover is positioned properly.

Positioning is key to making sure the safety cover not only fits perfectly, but also has straight straps and no wrinkles, says Trevor Olson, construction supervisor and technician with Classic Leisure Lifestyles in Penticton, B.C.

“I always keep six 19-L (5-gal) buckets in my truck, which I fill with water and use as weights around the perimeter of the cover to ensure it is positioned correctly before I start drilling the anchors,” Olson explains. “Also, I always bring a co-worker with me; the buckets and the second set of hands are key to ensuring the cover fits properly and looks good. “If you don’t have the cover laid out properly, you will find yourself adjusting straps to remove wrinkles, resulting in crooked straps—and homeowners hate the look of a crooked strap.”

Knapp uses a ‘spiderweb’ technique to ensure proper placement.

“We tether ropes across the entire width and length of the pool and set the cover on top of our web to ensure we have the cover positioned correctly,” he says. “We anchor each of our spiderweb ropes with rebar stakes and position and adjust the cover around the hardest parts of the pool first. Once we are satisfied that the cover is positioned correctly we drill our first hole.

“However, rather than following the pool’s perimeter when drilling, we drill the anchor points counter to one another. This crisscrossing technique allows us to adjust as we go, ensuring an even smoother, better fit, without any puckers.”

When drilling anchor points, keep in mind they should not be placed into concrete joints, as chipping can occur, and not too close to the edge of the deck, as a hammer drill can break the deck.

In terms of man hours, it takes most installers approximately one to two hours to plot the measurements for most safety covers; however, it can take half a day to install the cover.

Establish the centre point

It is critical to establish the centre points of the pool and safety cover before beginning to drill.

Not all manufacturers design their covers with a strap at the centre point. It is important to keep this in mind, especially when replacing an existing cover. It is critical to establish the centre points of the pool and safety cover to line them up during the initial placement of the cover before beginning to drill. Chalk lines are ideal for marking the deck and cover to determine the centreline.

Walls, reverse radius curves, raised spas and waterfalls

Design elements around the pool (e.g. raised spas and waterfall walls) often require the safety cover to be secured directly to the feature. To do this, installers need to drill directly into the feature’s wall and use a cable-fastening system, which can sometimes be a challenge.

A common mistake is not using enough eyebolts (cable anchors), especially around radiused features. For this anchoring method, cables are threaded through the eyebolts and pulled tight to secure the cover against the feature. If an improper number of fasteners are used, the cover will bunch up around the feature and cause ‘puckers’ and ‘gaps’ where debris can enter. In worst case scenarios, the safety of the cover may be compromised.

No professional wants to install more anchors into a feature then necessary, but there should be enough to ensure the cable pulls the cover up flush and tight.

Drilling into vertical wall features can be another installation challenge. In most cases, if it is a straight vertical wall there is no need to use a ‘cable’ anchoring system, as clips underneath the cover can be fastened directly into eyebolts on the wall.

“When the feature is only 457 to 610 mm (1.5 to 2 ft) tall, you can hang over the wall,” says Tripp. “However, if the feature is taller or harder to access, we find ourselves entering the pool in waders using battery drills to install anchor points. We have even found ourselves in small inflatable boats drilling around coves and grottos. For features like caves and grotto seats, I also sometimes use D-rings for anchor points.”

Olson also uses D-rings on installations involving narrow decks.

“As backyards are getting smaller and smaller, we are confronted with an increasing number of narrow decks that are only 3.6 to 4.5 m (12 to 15 ft) wide,” he says. “To compensate, we have D-rings installed on the cover straps on the deck’s narrow side; however, this makes placement even more critical, as the regular compression safety cover springs on the opposite side of the pool are forced to ensure a tight fit.”

Finally, make sure the cover manufacturer is aware of the features around the pool as they may recommend adding padding around certain obstacles, or on rough finish decks, pavers and flagstone, to avoid wear and tear on the cover.

Installing anchors into the landscape

Sometimes it is necessary to install an anchor into the ground. In these cases, depending on the soil, Knapp installs a thin wall pipe 152 to 305 mm (0.5 to 1 ft) into the ground. The anchor is then cemented in place and covered with mulch.

On another hand, Tripp has sometimes secured deck anchors on post holes in the ground with concrete, roughly 457 mm (18 in.) deep to create anchor points when dealing with landscaping close to the pool’s perimeter.

Although Olson tries to avoid anchoring straps into the landscape altogether, when other options are not present, he will drive a 12.7 mm (0.5 in.) piece of rebar 610 mm (2 ft) into the ground and fasten a 305-mm (1-ft) extension to it.

“A stake in the ground will still ‘flex’ over time,” he says, “so you can’t get the tightness around that particular anchor, making the other anchors more critical.”

A few final tips

It is important the cover’s fastening springs are not fully or under compressed. If pulled too tight, the springs are not able to expand and contract with the elements, such as additional weight for snow loads and ice. However, if they are not tight enough, safety can be compromised, as it may not prevent access to the pool, as pets and/or children may be able to get under the cover.

Before heading out to the job site to measure for a safety cover, be sure to have the correct tools on hand. Here is a list of items found in the tool bags of some seasoned professionals:
• Plumb bobs;
• Levels (several);
• Surveying stakes;
• Measuring tapes (30 m [100 ft], 7.62 m [25 ft] and 4.87 m [16 ft] lengths);
• Bag of pins;
• Chalk;
• Chalk line; and
• Painter’s tape.
• Good pair of waders (for shallow water);
• Inflatable, one-man raft (for deeper water);
• Drill (with extra bits);
• Hammer;
• Rope;
• Fastening equipment (e.g. compression springs, eyebolts, D-rings, cable, etc.); and
• Big ‘weight’ (e.g. sand bags, cinder blocks or water pails, etc.).


Shea_HeadshotJ. Kevin Shea is the senior vice president and chief marketing officer (CMO) for Vyn-All Pool Products, a manufacturer of inground and above-ground safety covers and vinyl liners in Newmarket, NH. With more than 30 years of pool industry experience, Shea has conducted seminars on measuring and installing safety covers for the Association of Pool & Spa Professionals (APSP) at local, regional and international levels. He can be reached via e-mail at[6].

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