The spa cover is perhaps the most important aspect for retaining heat and minimizing overall operating costs. Besides heat retention,
the cover helps to protect the water from dirt and debris as well as from evaporation. The cover is also one of the greatest security assets, preventing
small children and pets from falling into the spa. Oddly, as important as the spa cover is, it's overlooked by most consumers and passed over by many salesmen.
Determining the actual quality of a cover can be rather difficult. From the outside they pretty much all look the same, making it difficult to
determine a quality cover. Regardless of quality, the spa cover will almost certainly be the first thing that will need replacing on a spa, so it is important
to look for one of quality.
The insulating foam core of almost all covers in "expanded polystyrene" (Styrofoam). The strength and insulating ability of the foam is determined by it's
"density". Foam density refers to the weight of one cubic foot of foam. The higher the higher density, the greater the strength. Higher density also has a
slightly higher insulating factor, but only slight. Typically covers are made of 1#, 1-1/2# or 2# foam. For any spa outdoors in the rain and snow, and over
about 6-1/2' across, 1# foam is not acceptably strong enough. 2# foam can be rather heavy, but in areas that get lots of snow that could accumulate on the cover,
is most recommended. 1-1/2# density foam and an excellent all around choice.
The thickness of the foam of course had a direct impact on the strength and insulating ability as well. The vast majority of spa covers are
tapered, to allow water to easily run off, from 4" to 2". Be careful though, it's not unusual for a cover to be called 4", and yet be as thin as 3-1/2" thick.
There are a few manufacturers using thicker covers, up to 6" thick, and with these, a lighter density foam is more than acceptable. With the larger and heavier
covers, a cover lifter may become more of a necessity.
Hinge Sealing Gasket:
Most spa covers fold in half and the two halves have a gap between them. Typically the covers have some type of "sealing gasket" at the edges of the hinge to
seal the two halves and prevent steam from escaping. High quality covers will actually have a single "gasket" running the entire length of the hinge. This single
gasket can actually add 3% - 5% to the overall insulating ability of the cover.
The foam cores are protected from absorbing water by wrapping them in polyethylene plastic. Higher quality covers will have this "plastic" heat sealed rather
then being taped closed. Normal chemical use in the spa will slowly degrade the plastic to the point of becoming porous, thereby allowing water to enter and begin
being absorbed into the foam cores. The thicker the polyethylene the better, and the thickness can run from 2mil to 6mil thick.
Handles and Tie-Downs:
These are perhaps the weakest parts of most spa covers. Most handles are not designed nor intended to be used for lifting and moving the cover. Tie-downs that are
sewn into only the bottom of the covers skirt tend to fail in windy areas. Handles and Tie-Downs made of nylon webbing and sewn in at multiple points tend to be
Some municipalities may actually not allow a spa to be installed unless the cover meets ASTM standards (American Society of Testing and Materials), unless
approved child-proof fencing is also installed. Covers that meet ASTM standards are required to conform to certain safety aspects that reduce/eliminate access
to the spa by children under the age of 5 years. A cover that meets ASTM standards will be clearly and visibly labeled as to such on the outside of the cover.