Integrating hot tubs into backyard landscapes

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Since 1990, HydroTher Hot Tubs have been the #1 choice of architects, consultants, designers and facility operators for commercial aquatic applications.

By Vic Walker

When considering a swimming pool and hot tub in addition to an outdoor landscape design, many homeowners select a hot tub that is integrated into the pool form. This not only creates a cohesive look, but also allows the hot tub to be used as a design element with water flowing over or out into the pool. This is a common design premise. Installation concepts for portable hot tubs, however, can be a little more challenging when trying to make them look as integrated as their built-in counterparts.

In today’s modern backyard design, portable hot tubs have become quite popular with many homeowners as they are an ideal way to add hydrotherapy options to a landscape design and there are many interesting ways they can be incorporated. Some of the things that should be considered when installing a hot tub or swim spa include: ease of ingress and egress, general location in the backyard relative to the house or property views (e.g. overlooking a lake or other scenic feature) and making sure there is a safe path—to and from—with adequate lighting for safety.

Foundations and grade

Most hot tubs and swim spas are installed on grade (or level) with other features in the backyard. In most cases, they are typically installed on a poured-concrete foundation or other leveled, firm surface. However, while all hot tubs need to be installed on some sort of level ground, they do not necessarily need to be on a poured-concrete pad. Other masonry materials such as interlocking concrete pavers, dry-set tile, or even natural stone will work as long as they are secure. Hot tubs can even be installed on a pea-gravel base as long as it is thick enough (approximately 152 mm [6 in.]) and installed on a compacted soil base. Homeowners can even choose pre-fabricated plastic pads, which are designed specifically for hot tub foundations. These preformed pads are easy to set-up; however, they must be installed on a compacted, level surface as well.

Swim spas on the other hand, due to their size and weight, are typically installed on a steel-reinforced, poured-concrete pad with some form of footing design. Other methods of on-grade installations include using a simple concrete pad, gravel bed, or reinforced-wooden platform. These are some of the easier on-grade methods; however, sometimes they do not look as integrated into the landscape as other installation methods.

The vault

For homeowners looking for a more refined look, one option is to install their new hot tub or swim spa inside a vault. Vault installations offer many functional and esthetic advantages. For instance, they provide easier access for enhanced ingress and egress and can be built above or below grade depending on the design needs. In many instances, the materials used to finish a vault can be the same or complement other materials used in the landscape. For example, the exterior walls of an above-grade vault can be finished in stone veneer, tile, or any other material being used in the backyard.

For below-grade vaults, the access covers and adjacent deck can also be constructed of the same or complementing materials as other features. By using similar materials, the ability to further integrate the design into a landscape is enhanced—even if the hot tub is installed after the initial landscaping has been completed.

In addition to aesthetic concerns, proper design of the vault structure and other items are extremely important as they are essential to the hot tub or swim spa’s long-term stability. Other important considerations include: wall and support construction, drainage, and maintenance. A good vault design also makes routine maintenance easier by providing access to key areas, e.g. pumps and controls.

Basic vault concepts

Vaults are functional enclosures that should be constructed by a licensed contractor as there are many considerations that need to be addressed in order to design/build them correctly. A basic, but important, consideration is soil. For example, various soil types will play a factor in the design and size of the footing required for a vault wall, whether it is being built above or below grade. Further, the type of reinforcement bar required in the construction of the wall and footing will vary according to the wall’s thickness and what building and finishing materials are being used (e.g. stone veneer). Contractors will have experience working with different soils as well as local building codes; therefore, they should have a good idea of what footing design is required for any given design.

environmental water (e.g. rain and melting snow), but also splash out from the hot tub.

Another important consideration is drainage, especially for vaults designed below grade. These vaults require the installation of a drainage system that can not only handle environmental water (e.g. rain and melting snow), but also splash out from the hot tub or swim spa. This is a crucial design element in swim spa vaults as more water is pushed out of these spas during swimming and exercise. Ideally, vault drain systems should be tied into an existing landscaping drain. For projects using a gravel base, a ‘French drain’ (i.e. weeping tile) system can be employed, and depending on soil conditions, these drains are effective at handling excess water. Another option is to install a pump system that ties into exiting drains or evacuates water from the vault to another location. These pump systems use floats, which activate automatically once the water has reached a certain level. These pumps will keep the vault dry in rainstorms and during heavy usage.

Adequate access is also important to the design. The equipment in most hot tubs and swim spas are typically located in one area; therefore, it is a good idea to make this area accessible for routine maintenance and/or repair. Further, as hot tubs and swim spas need to be drained and filled frequently, drain outlets should also be easy to get to. In some cases, contractors can install a simple ball valve that can be easily reached when the hot tub is inside a vault. Water is then emptied right into the vault’s drain system, making this maintenance routine easier to perform. If the exterior cabinet of the hot tub or swim spa will also need maintenance, this should be considered in the design as well.

Finally, another form of access that should be well thought out is ingress and egress. Obviously, a set of integrated steps make above-grade vaults safer to use; however, they can become part of the integrated design by simply incorporating materials, which have been used throughout the backyard landscape, e.g. matching other steps or walls in the yard.

Vault styles can vary

Hot tub and swim spa installations are limitless in style and design. And, thanks to vaults, depending on the homeowner’s preferences and the design theme of their backyard, they can also be installed in a variety of configurations. Many vaults are identified by how much of the product is either hidden or revealed. While these are almost infinite, the following will discuss some of the more typical styles and/or configurations being used today.

Above grade

Above-grade (i.e. on-grade) vaults are one of the most popular styles as they do not require a large excavation. They do still require a footing; however, so some digging is necessary.


These full-vault structures are designed and built on grade to cover all sides of the hot tub. Its walls can comprise poured concrete, brick, or concrete masonry unit (CMU) blocks, and then finished in any one of a variety of hardscaping materials.


A full-height, on-grade vault is one which fully encloses the hot tub or swim spa and extends to the top of the unit. These vaults also typically include a maintenance access hatch in the front where the equipment is located. Often times, steps are built into the sides of the vault walls not only to promote ingress and egress, but to also create visual interest.


A full-height, three-wall vault is another popular option as this design creates more of an alcove by leaving one side of the hot tub exposed. These vaults can be built in a variety of heights depending on what the homeowner wants. For example, a vault can be built to cover only half of the hot tub or swim spa (i.e. a 50-50 installation). In some cases, this is more cost effective (since there is less to build); however, it still helps to blend the hot tub or swim spa into the landscape.

On-grade vaults can easily become the focal point of a backyard as the sides of the vault act as a canvas for the homeowner to decorate as they desire.

Below grade

When vault designs go into the ground, or below grade, they are typically classified by how deep they are set into the ground. For instance, just as its name suggests, half of a 50-50 vault is installed below grade, while the remaining half is above grade.

Vaults that are constructed below grade still provide the option of adding materials to the exterior portion of the walls to help incorporate the design with the adjacent landscaping. The lower height of below-grade walls can be less imposing, whereas the same size hot tub or swim spa feels and looks smaller and/or more integrated in a 50-50 below grade vault than it would in a 50-50 on-grade vault.

When designing and installing below-grade vaults it is important to design the walls and footings with enough retaining force to hold back the soil. Wall size and design will vary depending on soil conditions as well as the vault’s overall height. For example, if the vault is 0.76 m (2.5 ft) deep and has a 0.76-m exposed wall, the overall engineering and footing design will account for a 1.5-m (5-ft) wall. The wall’s thickness will also have a bearing on the footing design. A licensed contractor will be able to assist homeowners in designing these walls and footings; some hot tub manufacturers offer vault kits, which assist contractors when designing these structures to accommodate a new hot tub installation.

Similar to on-grade vaults, a 50-50 below-grade vault can be designed to leave half of the hot tub visible and not include any walls above grade. This variation involves excavating to the required depth and installing all retaining walls below grade, including the required foundation, drains, etc. For this style of design, it is still important to create an access hatch or area adjacent to the location of the pumps and/or equipment for maintenance repairs. The design (or height) variations are unlimited, thus allowing homeowners to select the style of vault that best suits their landscape and lifestyle.

Flush vaults

Just as the name suggests, a flush-vault design is one where the entire hot tub or swim spa, except for the bar top (the part the cover sits on), is recessed into the ground. This design is extremely popular; however, it requires a little more planning and engineering in some instances.


Drainage and maintenance access still need to be addressed; yet, when built correctly, flush vaults can provide the most integrated esthetic look when added into a landscape design. These vaults allow hot tubs to be installed at the same level as the homeowner’s inground swimming pool. Many flush-style vaults are designed with clearance access on all four sides, which is covered by a removable panel system constructed of a complementing material. For example, porcelain tile access panels installed adjacent to stamped concrete. This creates an attractive change in material on the ground and still allows for easy access to the vault.


In other designs, the surrounding materials can be installed flush with the edge of the vault, adding to the cohesive feel of the design by creating a seamless integration between the vaulted hot tub and the surrounding landscape. Only the equipment side of the hot tub or swim spa is made accessible with a removable panel.

When it comes to external views, these vaults provide a unique aspect for bathers. When inside the hot tub, bathers are at grade level with the surrounding landscaping, which enhances the feeling of privacy as well as the hot tub’s integration into the outdoor design.

Vault upkeep

Not only do vaults need to provide access to the hot tub or swim spa they house, but also to the items that might need to be maintained on the vault itself. This includes being able to remove dirt and debris from the vault and/or verify that it does not contain any standing water. Since most vaults have walls either above or below ground, odd items can become trapped inside. It is also a good idea to provide some form of lighting and/or power outlet as a convenient way to help in the maintenance process.

Incorporate a vault into the next project

While vault installations may not be the answer for every homeowner, if designed/installed correctly, they can become a feature item in the backyard. When constructing a hot tub or swim spa vault, one needs to consider the overall landscape design as well as local construction and building code regulations. Building a secure and safe vault will not only provide homeowners with years of use, but will add value and beauty to their backyard project.

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