The Complete Guide
Custom Made Outdoor Spa Covers — The Complete Owner's Guide
A portable spa or hot tub is a significant investment. The cabinet, plumbing, and control systems are built to handle water from the inside, but they are not always designed to cope with years of direct sun and weather from the outside. This guide explains how an external cabinet cover works and how to measure for one.
What this cover is for
It is worth being clear about what this product does. A portable spa has two distinct things that need protecting. The first is the water surface, which is typically covered by a foam-filled vinyl lid that sits directly on the water. That lid usually comes with the spa.
The second is the external cabinet — the panels on the sides and base of the unit that enclose the plumbing, motor, heating elements, and control systems. Most spa owners do not think about covering this part until something goes wrong.
This cover goes over the whole outside of the spa cabinet. It is fitted when you want to protect the exterior from extended exposure to UV, rain, bird mess, falling leaves, and anything else that lands on the outside of the unit.
How to measure the cabinet
Width
Width is the longest outside measurement of the cabinet, taken at the widest point. On most rectangular spas this is straightforward. On square spas, width and depth will be the same. Measure the cabinet itself, not any steps or handrails placed alongside.
Depth
Depth is the measurement across the shorter side, front to back. Take it at ground level across the cabinet panels. If the cabinet tapers slightly at the base, measure at the widest point.
Height
Height runs from the ground to the top edge of the cabinet, which is the lip or frame that the inner lid sits on. Do not include the inner lid, the foam cover, or any accessories that sit above that lip. The cover is for the cabinet, so the height measurement ends where the cabinet ends.
Why the cabinet needs protection
The cabinet panels on most portable spas are made from a synthetic wood composite or a UV-stabilised polymer. Both are designed to resist normal outdoor exposure, but neither is completely immune to extended UV in outdoor conditions.
The problem compounds over time. UV breaks down the surface finish on the panels, which makes them more porous. Once the surface starts to crack or fade, moisture can get behind the panels, which causes warping and eventually compromises the panel fixing points. Replacing cabinet panels is expensive and on some spa models is not straightforward.
The control panel area is another point of concern. Most spa controls are rated for splashing from inside the spa, but prolonged rain exposure from outside can get into seams and connections over time.
Material for spa cover use
Woven polypropylene base
The cover is made from silver laminated woven polypropylene. The base is a tightly woven polypropylene, which is strong, tough, and resists tearing. A spa cabinet has corners and edges that put strain on a cover, so the weave matters. It holds together where a thin sheet fabric would split.
Silver reflective laminate
The outside of the fabric carries a silver laminate coating. That coating is reflective, so it bounces sunlight away from the cover. The result is that the cover and the cabinet underneath stay cooler and are shielded from sun and UV. The same coating is water resistant. It sheds rain and keeps it off the cabinet panels rather than letting it soak through.
Weight and durability
At 350gsm this is a heavier, more substantial fabric than the thin covers sold for the same job. The extra weight helps the cover hold its shape over the cabinet instead of flapping or bunching. It is still a cover, not a tarp, so one person can fit it and take it off without help. Cheap covers tend to fail fast in the sun and wind. A heavier coated fabric lasts through more seasons before it shows wear.
Fitting and care
Fit the cover over the cabinet when the spa is not in regular use, such as over winter or for extended periods away from home. Remove it before use and allow any condensation or moisture to dry before refitting.
Rinse the outside of the cover with a hose occasionally to remove dust, bird marks, and general buildup. Do not machine wash. Spot clean any marks with warm soapy water and a soft cloth, then allow to dry completely before storing or refitting.