Should My Sauna Be on Concrete, Wood Decking, Gravel or Grass?

In short, concrete and wood decking are perfect and, if built properly, are the best ways to have a solid foundation for your outdoor sauna. Gravel and grass are not recommended, as both can cause movement or sinking.

Are you considering adding a sauna to your home? Before you can start relaxing and enjoying all the sauna health benefits, there's one important question to sort out first. What should your sauna actually sit on?

The base you choose affects how stable your sauna feels, how long it lasts, and how easy the setup is. The good news is you’ve got a few solid options. It really comes down to what you already have in your backyard and how permanent you want the setup to be.

Quick Overview

• ✅ Concrete: most stable and low maintenance

• ✅ Wood decking: looks great, works well if built properly

• ❌ Gravel: not recommended

• ❌ Grass: not recommended

• Always aim for a flat, level surface

• Make sure there’s good drainage underneath

Is a Concrete Base good for a Sauna?

Image: Verified Buyer Lex G.

Yes! A concrete pad is the most common choice. It's level, stable, and built to last. It gives you a flat, solid surface that won’t shift. Once it’s in place, there’s not much to think about. It handles weight well and works in all weather conditions.

If you're starting from scratch, talk to a local builder about pouring a simple concrete pad. A thickness of around 100mm is usually plenty for a residential sauna.

Best for: Long-term installations, flat sites, and anyone who wants a set-and-forget foundation.

Is a Wood Decking good for a Sauna?

Yes. Kiwis are deck lovers, and plenty of our customers already have a beautiful deck that's crying out for a sauna. The great news is that most well-built decks can handle the load. However, you have to check with a professional first. Wood decking looks more natural and blends in nicely with outdoor spaces. You just want to make sure the deck is strong enough to support the sauna.

 It's also a good idea to ensure adequate ventilation beneath the deck to prevent moisture buildup over time.

Tip: It's also a good idea to ensure adequate ventilation beneath the deck to prevent moisture buildup over time.

  Existing outdoor living areas, elevated sections, and creating that resort-style backyard vibe.

Best for: Existing outdoor living areas, elevated sections, and creating that resort-style backyard vibe.

Is a Gravel Base good for a Sauna?

No. Gravel is not recommended as a base for an outdoor sauna, as it can cause movement or sinking over time.

Is a Grass Base good for a Sauna?

No. Just like Gravel, Grass is not recommended as a base for an outdoor sauna, as it can also cause movement or sinking over time.

So, Which Base to Choose For my Sauna?

Honestly, Concrete and Wood Decking (if built properly) work well. Concrete gives you maximum stability and decking integrates beautifully with your outdoor space. The most important thing is that your base is level, stable, and allows for drainage. We have small outdoor saunas (1-2 people), medium outdoor saunas (3-4 people) and large outdoor saunas (5+ people).

If you’d like personalised advice, our team is always happy to help you compare models and find the perfect fit for your home. We've helped Kiwi right across the country find the perfect sauna setup.

Also check out our The Ultimate Sauna Buyers Guide: Benefits, Costs, Installation & More in New Zealand or visit our Alpine Recommender™: