Updated 10.02.2026

Building an outdoor sauna is becoming one of the most popular wellness upgrades for UK homeowners. According to the British Sauna Society, the number of public saunas in the UK doubled between 2023 and 2024, and were expected to double again by the end of 2025!

Google searches for “home sauna” rose 37% and “infrared sauna” 76% from Dec 2024 to Feb 2025. The overall UK sauna market hit USD 78.5 million in 2024, projected to grow at 7.3% CAGR to 2033, including outdoor and residential segments.

Traditional saunas offer an authentic way to relax, rejuvenate, and create a peaceful retreat in your own garden.

Whether you’re considering a DIY sauna kit or a fully custom build, understanding all the possible associated costs is key to setting up your home wellness space – on your terms.

In this guide, we’ll take a detailed look at what goes into the cost of building an outdoor sauna, so you can make the right investment for your garden and lifestyle.

Before we get started, a quick word…

Choosing the right sauna can quickly become a headache.
Behind the facade of perfect descriptions and attractive photos, many sellers rely on hidden compromises:

• Thin wood panels that feel flimsy underfoot and warp over time
• Bargain timber that can’t handle the heat cycle, cracking and degrading prematurely
• Insufficient insulation or wall thickness – bleeding heat almost as quickly as it arrives, along with your money
• Poor construction causes noise and creaking on every movement, a reminder that this sauna may not last for many seasons

These issues are rarely visible at first. They reveal themselves in everyday use: long heat-up times, stifling rather than enveloping heat, creaking sounds, visible cracks, or early breakdowns that turn relaxation into frustration.

This is precisely what Summerhouse24 saunas are designed to avoid.

Summerhouse24 designs and manufactures its saunas in-house, in Estonia – Finland’s cultural sibling, sharing the same long-standing sauna tradition.

Each model is developed by specialists raised in authentic Nordic sauna culture, with a practical understanding of real-world use – not just theory.

In practice, this means:

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At Summerhouse24 were not here to close a sale – we’re here to open the door to a sauna that feels just as right a decade from now

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Understanding outdoor sauna costs in the UK

Outdoor sauna prices in the UK can vary widely depending on the size, materials used in the build, and the construction method. In 2025, homeowners can expect to spend anywhere from £2,000 for a compact, prefabricated unit to £15,000 and above for a large custom-built sauna with premium finishes.

💡Prefabricated sauna cabins usually offer the best value, provided you choose an experienced manufacturer and seller, such as Summerhouse24.

Summerhouse24 combines traditional Finnish sauna cabin design with modern manufacturing efficiency – allowing you to enjoy a genuine sauna experience without the unpredictable costs of a sauna built on site. Why not have a look at some of the sauna cabins right now?

Key cost factors to consider

Size and capacity:
Naturally, a 2-3 person sauna will cost less than a family-sized cabin designed for 6-8 people. Larger structures require more timber, insulation, and installation time, all of which increase the price.

Material quality:
The type of wood used is one of the biggest factors in price. Nordic spruce is the traditional choice for authentic saunas – it’s dense, durable, and retains heat exceptionally well. It does cost more than softer, southern woods, but the difference in longevity and comfort is noticeable.

Heating system:
Wood-burning saunas are generally cheaper upfront, though they do require a chimney. Electric heaters, on the other hand, provide precise temperature control and ease of use, but they may slightly increase running costs. The Finns and Estonians, known for their sauna tradition, typically prefer wood-burning saunas, since electric saunas tend to have dryer air.

Foundation requirements:
Most outdoor saunas require a solid, level base such as concrete or paving slabs. A concrete base is one of the most expensive types of bases and can cost anywhere from a few hundred pounds to thousands, depending on the size and your location. Unless you are experienced in this type of work, it’s not recommended to undertake building the foundation yourself. An uneven foundation can cause damage to the structure on top or even be a safety hazard. 

Additional features:
Windows, changing areas, covered terraces, and premium glazing all add comfort – but they also cost more. It’s a good idea to first be clear on what are the most important elements you don’t want to skimp on.

DIY outdoor sauna cost

For hands-on homeowners, DIY sauna kits have the best balance. A DIY outdoor sauna kit typically costs between £3,500 and £8,000, depending on size and specifications.

Good quality prefabricated DIY sauna cabins are specifically designed for straightforward self-assembly. Summerhouse24 kit components fit together systematically and even the holes for screws are pre-drilled. Every design is based on authentic Finnish and Estonian saunas – ensuring a genuine sauna experience that stays true to tradition.

Why DIY sauna kits are cost-effective

High-quality prefabricated sauna kits often include premium components as standard – things that would add hundreds or even thousands to a bespoke build. Summerhouse24 sauna kits include:

• German-engineered tilt-and-turn windows with multi-locking points
• Toughened safety glass
• Double glazing
• Factory pressure-treated base timbers ready for immediate installation
• Heavy-duty roofing capable of withstanding up to 200 kg/m² of snow load

Smaller models are perfectly suited for weekend assembly, often requiring just one or two days with a helper. Still, it’s always worth checking with the supplier about your site conditions before you start!

Outdoor sauna installation cost

If DIY isn’t your style, professional installation is readily available. Installation costs for Summerhouse24 prefabricated saunas range from £1,250 to £2,890, depending on model size.
Smaller 2–3 person saunas start at around £1,250 for installation, while larger 6–8 person models can reach £2,890.

Electrical work

If you decide to opt for an electric heater, a Part P certified electrician is required for installation. Expect an additional £300–£600, depending on cable distance and electrical circuit requirements. Always include this in your budget planning.

Cost by Sauna Size

Size	Capacity	Sauna Kit	Installation	Ideal For
Small (2–3 people)	2 m × 2 m	£3,500-£5,500	£1,250-£1,600	Couples or solo users
Medium (4–5 people)	3 m × 2.5 m	£5,500-£8,500	£1,800-£2,200	Families and wellness fans
Large (6–8 people)	4 m × 3 m+	£8,500-£12,000+	£2,200-£2,890	Social use or semi-commercial setups

Larger builds may require planning permission depending on floorheight and proximity to boundaries, so check with your local council before starting.

Complete outdoor sauna investment breakdown

Initial costs:

• Sauna kit: £3,500-£12,000
• Professional installation: £1,250-£2,890
• Foundation: £300-£800
• Electrical connection: £300-£600
• Delivery: £150-£400

Additional essentials:

• Heater (if not included): £400-£1,500
• Sauna stones: £30-£80
• Accessories (bucket, ladle, thermometer, etc.): £100-£200
• Wood treatment: £80-£150 (make sure to choose a high-quality one)

Running costs:

• Electric heaters: approx. £1–£2 per session; annual use (2–3 × weekly): £150–£350
• Wood-burning sauna: approx. £80–£180 per year for firewood
• Maintenance: £100–£200 annually for cleaning, treatments, and minor repairs

Outdoor sauna & steam room combo cost

If you’re after a luxury spa feel, a sauna-steam combo is the top-tier option. Prices for combination units start from £12,000 and can reach £25,000 for high-end designs with dual heating systems, waterproofing, and enhanced ventilation.

While energy costs are around 30-50% higher than a standard dry sauna, these multi-functional cabins offer the best of both worlds for true wellness enthusiasts.

How do I choose the right sauna?

When weighing your options, think about your lifestyle and how often you’ll use your sauna:

• DIY enthusiasts: Get satisfaction and savings with self-assembly kits.
• Busy homeowners: Choose professional installation for convenience.
• Families: A medium-sized model balances cost and capacity.
• Hosts & entertainers: Larger cabins are perfect for group use and relaxation.

Ultimately, investing in an authentic cabin from an experienced manufacturer ensures lasting sauna performance, energy efficiency, and genuine wellness benefits for years to come.

Your outdoor sauna isn’t just a structure – it’s a long-term investment in health, relaxation, and quality of life. By understanding the real costs and choosing wisely, you’ll create a space that brings warmth and wellbeing to your garden for decades. 

If you have any questions about Summerhouse24 sauna cabins, don’t hesitate to call us at 020 3807 0369 (weekdays: 9 am – 5:30 pm, weekends: 10 am – 4 pm.)

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Sources:

1. https://www.britishsaunasociety.org.uk/
2. https://www.grandviewresearch.com/horizon/outlook/sauna-market/uk