How to Prepare Your Garden for an Outdoor Sauna Installation

Whether you're installing a compact two-person sauna or a large family-sized outdoor cabin, this guide explains everything you should do before delivery day, from choosing the right location and preparing a solid foundation to understanding UK planning rules, electrical requirements and the finishing touches that transform a sauna into a complete wellness retreat.

1. Choose the Best Location for Your Outdoor Sauna

The location of your sauna will affect far more than its appearance. It influences installation costs, electrical complexity, privacy, drainage and—perhaps most importantly—how often you'll actually use it.

Many homeowners instinctively place a sauna in the furthest corner of the garden, believing it should be hidden away. Whilst this might seem logical, it often creates unnecessary complications. Longer electrical cable runs increase installation costs, excavation becomes more expensive and walking across a cold, wet garden during winter is considerably less appealing than stepping just a few metres outside the back door.

If your goal is to build a sauna habit, convenience matters. A sauna that's easy to reach becomes part of your weekly routine. One that's tucked behind sheds and flower beds often ends up being used far less than expected.

Privacy should also be a priority. Few people want to cool down after a sauna while overlooked by neighbouring properties. Positioning the sauna behind fencing, hedging, decorative screens or carefully planned landscaping can create a much more peaceful and secluded environment without making the space feel enclosed.

Think about your surroundings too. A sauna overlooking a garden, woodland or open countryside naturally creates a more relaxing atmosphere than one facing a brick wall or wheelie bins. Whilst views may seem like a luxury, they can dramatically improve the overall experience and encourage more regular use.

Before committing to a location, ask yourself:

• Is it easy to reach all year round?
• Is there enough privacy?
• Will rainwater drain away naturally?
• Is there sufficient room around the structure?
• Will electricians and installers have easy access?

Choosing the right location at the outset prevents costly compromises later.

2. Build a Proper Foundation Before Installation

Every outdoor sauna is only as good as the surface beneath it.

Timber cabins are engineered with remarkable precision, but they still rely on a perfectly level, stable foundation to perform properly for decades. Installing a sauna directly onto grass, soil or uneven paving is one of the biggest mistakes homeowners make.

Whilst the sauna may initially appear level, the ground beneath it will naturally expand and contract with changing weather conditions. The UK's wet winters, occasional frosts and increasingly dry summers all contribute to seasonal ground movement. Over time, this can cause the structure to settle unevenly, placing unnecessary stress on doors, glazing panels and roof joints.

A poorly prepared base can lead to:

• Doors becoming difficult to close
• Windows falling out of alignment
• Timber movement and distortion
• Water collecting underneath the sauna
• Reduced structural lifespan

For most installations, a reinforced concrete slab provides the best long-term solution. It distributes weight evenly, offers excellent durability and requires very little maintenance.

Other suitable foundations include:

• Concrete paving slabs laid on a compacted MOT Type 1 sub-base
• Structural reinforced decking designed for heavy loads
• Engineered gravel foundations specifically built for garden buildings

Whichever option you choose, the foundation should support not only the sauna itself but also the heater, sauna stones, benches and several occupants. Depending on size, a fully assembled outdoor sauna can weigh hundreds of kilograms before anyone steps inside.

A properly prepared base may add a little time at the beginning of the project, but it protects your investment for decades.

3. Do You Need Planning Permission for an Outdoor Sauna?

One of the first questions most homeowners ask is whether planning permission is required.

The good news is that, in many cases, the answer is no.

Most domestic outdoor saunas are treated as garden outbuildings and fall under Permitted Development Rights, meaning formal planning permission is often unnecessary provided certain conditions are met.

These generally relate to:

• Overall building height
• Distance from boundaries
• Position within the garden
• Percentage of garden occupied by outbuildings

However, there are important exceptions.

If your home is listed, located within a conservation area, situated in a National Park or subject to Article 4 Directions, different rules may apply. Larger sauna buildings or those intended for commercial use may also require planning approval.

Even if planning permission isn't required, it's worth checking with your local planning authority before ordering. A quick enquiry can prevent delays and provide complete peace of mind before installation begins.

4. Plan Your Electrical Supply Early

Electrical installation is one of the areas where homeowners most commonly underestimate both complexity and cost.

Unlike many garden buildings, an outdoor sauna contains a powerful heater designed to raise temperatures to between 70°C and 100°C. That requires a properly designed electrical supply capable of handling continuous high loads safely.

The exact specification depends on the heater you choose. Smaller models naturally have lower electrical demands than larger family saunas, but virtually every electric sauna benefits from a dedicated supply installed by a qualified electrician.

The final installation may involve:

• A dedicated circuit
• Appropriate cable sizing
• RCD protection
• Weatherproof external connections
• Compliance with Part P of the Building Regulations

The further your sauna is from the consumer unit, the more cable, excavation and labour will be required. For some properties, simply moving the sauna 10 metres closer to the house can reduce installation costs significantly.

If you're purchasing your sauna before arranging an electrician, ask the supplier for the heater specifications early so installation can be planned well in advance.

5. Don't Ignore Drainage

Outdoor saunas are designed to cope with British weather—but standing water is still one of their biggest long-term enemies.

Even pressure-treated timber benefits from being kept as dry as possible. Constant moisture beneath the structure slows airflow, encourages algae and moss growth and creates an environment where timber remains damp for longer after rainfall.

Before installation, inspect how your garden behaves after heavy rain.

If puddles regularly form where you intend to install the sauna, choose another location or improve drainage before work begins.

Simple improvements include:

• Installing gravel around the perimeter
• Creating a slight fall away from the structure
• Using permeable surfaces
• Adding drainage channels where necessary

Good drainage not only protects the timber but also keeps the surrounding area cleaner, reducing mud, standing water and slippery surfaces during winter.

6. Check Delivery Access Before You Order

One surprisingly common reason installations are delayed has nothing to do with the sauna itself.

The installers simply can't reach the garden.

Before placing your order, walk the delivery route from the road to the installation site.

Measure:

• Garden gates
• Side passages
• Alleyways
• Steps
• Narrow corners
• Height restrictions
• Overhanging trees

Many outdoor saunas arrive as large flat-pack components rather than individual pieces of timber. Whilst they are designed for assembly on site, wall sections and roof panels can still be substantial.

Restricted access may require additional labour, specialist lifting equipment or even cranes in some situations.

Five minutes with a tape measure can save hundreds of pounds in unexpected installation costs.

7. Leave Space Around the Sauna

A common mistake is trying to squeeze the sauna into the smallest possible corner.

Whilst this maximises garden space initially, it often creates problems later.

Leave adequate clearance around the building for:

• Routine maintenance
• Cleaning
• Ventilation
• Roof overhangs
• Future servicing
• Timber movement

Good airflow helps the exterior dry naturally after rain, reducing moisture build-up and prolonging the life of the timber cladding.

It also makes annual maintenance such as cleaning, staining or oiling considerably easier.

Think of the sauna as a small building rather than a piece of garden furniture.

8. Create a Complete Outdoor Wellness Space

Installing the sauna is only the beginning.

The most successful outdoor wellness spaces are designed around the entire experience rather than the heat alone.

Traditional Finnish sauna culture revolves around cycles of heating, cooling and resting. After leaving the sauna, the body gradually cools before returning for another round of heat.

You can recreate this at home by adding complementary features such as:

• A cold plunge tub
• An outdoor shower
• Comfortable seating
• A fire pit
• Soft garden lighting
• Timber decking
• Privacy planting
• Storage for towels and robes

Even relatively simple additions can completely transform how the space feels.

Lighting deserves particular attention. Warm, low-level lighting creates a relaxing atmosphere for evening sessions whilst improving safety during darker winter months.

Similarly, adding evergreen planting or ornamental grasses around the sauna helps soften the structure visually, making it feel like a natural extension of the garden rather than an isolated cabin.

These finishing touches often make the difference between simply owning a sauna and creating a space you'll genuinely look forward to using every week.

Common Outdoor Sauna Installation Mistakes

Many installation issues are entirely avoidable with proper planning.

Mistake	Potential Consequence
Installing directly onto grass	Structural movement and uneven settlement
Choosing poor drainage	Standing water and reduced timber lifespan
Not planning the electrical supply	Unexpected installation costs and delays
Forgetting delivery access	Difficult installation and additional labour
Placing the sauna too far from the house	Higher electrical costs and reduced day-to-day use
Ignoring planning restrictions	Potential planning complications
Leaving insufficient clearance	Difficult maintenance and poor ventilation

Outdoor Sauna Installation Checklist

Before delivery day, make sure you've completed the following:

• ✓ Selected the best location
• ✓ Built a level, stable foundation
• ✓ Checked planning requirements
• ✓ Arranged a qualified electrician
• ✓ Planned drainage around the base
• ✓ Measured all delivery access points
• ✓ Allowed sufficient clearance around the sauna
• ✓ Planned any additional wellness features

Frequently Asked Questions

What is the best base for an outdoor sauna?

A reinforced concrete slab is generally considered the best option because it provides exceptional stability, durability and load-bearing capacity. Well-installed paving or structurally engineered decking can also work provided they remain completely level and adequately support the sauna's weight.

Can I put an outdoor sauna on decking?

Yes, provided the decking has been specifically designed to carry the combined weight of the sauna, heater, sauna stones and occupants. Standard domestic decking may not always provide sufficient structural support.

Do I need planning permission for an outdoor sauna in the UK?

In many cases, no. Most outdoor saunas fall within Permitted Development Rights. However, listed buildings, conservation areas and certain larger installations may require planning approval, so it's always worth checking before purchasing.

How much electricity does an outdoor sauna need?

The electrical requirements depend on the size of the sauna heater. Larger heaters require more substantial electrical supplies, so always consult both your supplier and a qualified electrician before installation.

How close should an outdoor sauna be to the house?

There is no fixed rule, but placing the sauna reasonably close to your property usually reduces installation costs, shortens electrical cable runs and makes it far more convenient to use throughout the year.

Final Thoughts

Installing an outdoor sauna is about much more than assembling a timber cabin. Proper preparation determines how well the sauna performs, how much it costs to install and how enjoyable it is to use for years to come.

By choosing the right location, investing in a stable foundation, planning your electrical installation, ensuring effective drainage and thinking carefully about the wider wellness space, you'll avoid the most common mistakes homeowners make and create an outdoor retreat that's built to last.

Take the time to prepare your garden properly before delivery day, and you'll be rewarded with a sauna that's not only easier to install but one that becomes a genuine part of your everyday lifestyle.