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.
Foam Density:
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.
Vapor Barrier:
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 significantly stronger.
ASTM Listing:
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.
