Today’s pools are often adorned with raised spas, waterfalls, vanishing edges and exotic caves. But as beautiful as these may be, professionals are left with the task of outfitting them with safety covers. With the proper measurements, a safety cover can be designed to look and fit great on any pool. Yet there are many challenges to measuring and installing safety covers on complicated poolscapes. Here are some simple rules and tricks of the trade used for measurement and installation.

Measuring the perimeter

Measuring a pool’s perimeter is simple for some shapes. However, with kidney-shaped or freeform pools, a surveying technique called “triangulation” (also called “plotting” or “A-B”) should be employed. It’s a good idea to use the manufacturer’s safety forms and have them on hand at the project site.

Before recording the A-B triangulation measurements, be sure both points are exact. If they are off by even 1 inch, every measurement in the project will be inaccurate. To avoid this, use well-secured surveying stakes when taking measurements. The stakes must remain secure until the cover is installed. If you need to return to the site to clarify a measurement for the manufacturer, the stakes should still be perfectly secured and the numbered points still visible to check the measurements originally provided.

Some manufacturers provide plotting software which can be entered on a laptop at the job site. This can identify points that are not plotting out correctly BEFORE you leave the site and turn these measurements in to the manufacturer.

Marking measuring points

Street chalk is commonly used to number points that can be checked later on. For decks that are too nice to mark up, blue painter’s tape comes in handy. Label each point on the tape and leave it in place to refer to the points even when installing the cover. Avoid duct tape — sometimes the glue comes off after being heated by the sun and it can be cumbersome to remove the residue from the coping.

Note all obstacles

Document any obstacles within 3 feet of the pool’s perimeter, including decorative rocks, planters, minimal/limited deck, raised spas and walls. Remove all obstacles, including rails and ladders, when possible. It is a good idea to take photos of everything around the pool because many questions can be answered just by seeing it.

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 cutouts for ladders because getting a cover to fit snuggly around a stainless steel tube can be difficult.

Measure vanishing edges

Measuring a pool with a vanishing edge can present a few challenges. On these pools, the safety cover is generally fastened to the vertical wall behind the vanishing edge; in some cases, the collection trough might 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.

Measuring replacement safety covers

Many installers have seen an increase in demand for replacement covers. 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 or at least the points at which the straps cross the cover’s perimeter. Sometimes if the anchors were not positioned correctly to begin with, plotting to the anchor points can make matters worse. Use your best judgment but be consistent with your method.


Before drilling holes in the deck, it’s important to lay the cover over the pool first to position it correctly. Sandbags or cinder blocks can be used to hold the cover in place, but if using cinder blocks, place something on the cover to protect it from damage.

When positioning the safety cover, start with the areas around obstacles. Make sure all cutouts are lined up perfectly, then adjust around the perimeter of the pool.

Some installers use a “spiderweb” technique to ensure proper placement. Tether ropes across the width and length of the pool, then set the cover on top of the web. Each of the ropes is anchored with rebar stakes to allow adjustments in positioning the cover. Once the cover is positioned correctly, you can drill the first hole.

Many installers follow the pool’s perimeter when drilling, while some drill the anchor points counter to one another. This crisscrossing technique allows installers to adjust as they go, ensuring a smoother fit.

Anchor points should not be drilled into concrete joints because chipping can occur. Nor should they be placed too close to the edge of the deck because a hammer drill can break the deck. It is also important that 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 and ice. But if they aren’t tight enough, safety can be compromised, and children and pets might be able to get under the cover.

Elements around the pool, such as raised spas and waterfalls, 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. The safety of the cover may even be compromised. Don’t install more anchors into a feature than 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 because clips underneath the cover can be fastened directly into eyebolts on the wall.