How to Choose the Right Oversized Spa Cover

ChrisG December 20, 2025

An oversized spa cover is any cover larger than 96 inches in length or width.

Once a spa goes beyond standard cover dimensions, the construction, panel layout, measuring process, and final fit require more planning.

At Spa Covers Etc., we build oversized spa covers using panels up to 120 inches wide. Length is much more flexible because additional panels can be added as needed.

That allows us to build covers for very large spas, swim spas, built-in plaster spas, fiberglass spas, and unusual installations that cannot use a standard two-panel cover.

What Is Considered an Oversized Spa Cover?

For our covers, anything larger than 96 inches in either direction is considered oversized.

Examples include:

A spa that is 108″ x 108″
A swim spa that is 90″ x 192″
A large built-in plaster spa
A wide fiberglass spa
An unusually shaped spa that requires multiple panels

Oversized covers are built with Heavy Duty 2.0 lb foam because the larger panels require additional strength.

Depending on the total size, the cover may be built in three pieces, four pieces, or with additional sections.

How Large Can an Oversized Spa Cover Be?

We can build oversized spa covers using panels up to 120 inches wide.

For length, additional panels can be added, which means we can build covers for very long spas and swim spas.

The final number of panels depends on:

Overall length
Overall width
Shape of the spa
Where the cover needs to fold
How the cover will be handled
How the spa is installed

For some covers, a three-piece layout works well. Larger spas may require four pieces or more.

Some oversized covers may also use a special center panel depending on the overall dimensions.

Start With How the Spa Is Installed

Choosing the right oversized spa cover starts with understanding how the spa is installed.

The correct way to measure a built-in plaster spa is not always the same as the correct way to measure a raised fiberglass spa.

This is one of the most important differences between a standard portable spa and a custom oversized installation.

Built-In Plaster Spas

For a built-in plaster or Gunite spa, the cover normally needs to sit securely on the surrounding coping.

The cover should not be made only to the size of the water opening.

Instead, we need to know the water span and then determine how much additional coverage is needed so the cover rests properly on the coping.

In many cases, this means adding approximately 3 to 4 inches per side, or 6 to 8 inches overall, beyond the water opening.

The exact amount depends on the coping, shape, surrounding deck, and where the cover can sit securely.

For oversized built-in spas, the way the cover rests on the coping is just as important as the overall dimensions.

Raised Fiberglass Spas

A fiberglass spa may be installed several inches above the deck.

In that case, the cover can often be built to fit the spa shell itself and use a skirt to cover the exposed side of the spa.

The skirt hangs down around the outside edge and provides a cleaner finished appearance.

For this type of installation, the cover may not need to extend onto the deck at all.

Recessed Fiberglass Spas Require a Judgment Call

Recessed fiberglass spas can be more complicated.

If the spa shell is close to deck level, there may be more than one possible way to build the cover.

For example:

Build the cover to fit the fiberglass spa itself and use little or no skirt
Make the cover larger so it rests on the surrounding deck
Adjust the size based on raised controls, trim, or uneven deck areas
Use a combination of overlap and skirt depending on the installation

This is where experience matters.

The right choice depends on how the spa sits in the deck and where the cover will have proper support.

Should the Cover Fit the Spa or Rest on the Deck?

There is no single answer for every oversized spa.

The best design depends on the installation.

For a built-in plaster spa, the cover usually needs to rest on the coping.

For a raised fiberglass spa, it often makes more sense to fit the shell and use a skirt.

For a recessed fiberglass spa, we may need to decide whether the better solution is to:

Fit the spa closely
Make the cover larger
Let the cover rest on the deck
Use a skirt
Avoid a skirt entirely

The goal is to create a cover that is properly supported, fits the installation, and can be handled safely and practically.

Panel Layout Matters

Large covers need to be divided into sections that make sense for the size and shape of the spa.

A poorly planned panel layout can make the cover too difficult to move or create awkward folding points.

When choosing the layout, we consider:

The total dimensions
Which direction the cover should fold
How the sections will be removed
Where handles are needed
Whether the cover will use a lifter
Whether access is limited by walls, railings, landscaping, or structures

The largest possible panel is not always the most practical panel.

Unusual Shapes and Templates

Oversized spas are often not perfect rectangles.

They may have:

Rounded ends
Oval sections
Large radiuses
Cut corners
Angled sides
Free-form shapes

Some shapes can be built from measurements alone.

More complicated shapes may require a full-size template.

A template is especially important when small differences in shape could affect where the cover rests or how the sections line up.

Heavy Duty Construction Is Standard Over 96 Inches

All of our oversized spa covers over 96 inches are built with Heavy Duty 2.0 lb foam.

The larger size of the panels requires stronger construction than a standard cover.

The final design also depends on the total span and the number of panels needed.

For oversized covers, the complete construction matters, including:

Foam density
Panel size
Reinforcement
Hinge layout
Vapor barrier
Exterior material
Proper fit

Locking Tie-Downs Are Available

Oversized and swim spa covers can be built with locking tie-downs.

These help secure the cover when the spa is not in use.

However, oversized covers over 96 inches are not ASTM child-safety rated.

That distinction is important when choosing a cover for a spa used around children or pets.