What wood should you use to build a sauna?
Look we know you’ve thought about it…
We get it all the time…
We give a potential customer the price of a Sauna, and they think:
“Nah! I could build that for cheaper myself”.
Next thing you know they are popping off to B&Q to buy some cheap tongue and groove and throwing together their very own Sauna.
And it looks alright…for a while….
But then, the wood starts to crack and shrink. Suddenly it doesn’t look so great anymore, and they wonder where they went wrong.
It’s important. I mean, it literally makes up the majority of a sauna. That’s why it’s important to use wood that is suitable for saunas, not just whatever you can get your hands on.
In this blog post we’ll look at why the wood is important, what properties it should have and what wood that we recommend you use for building your sauna.
Bear in mind that we’re talking about wood for indoor Saunas (which is all that we provide). If you are looking at an outdoor sauna (like some of the barrel ones you get), make sure the wood is suitable for our beautifully wet climate in Scotland. What is suitable for some parts down south or abroad, may not love the humidity and wetness of our lovely climate.
Where is the wood in your sauna?
Yeah it might sound like an obvious question, its literally all around.
But there are a few different places that wood will be found in a sauna.
Wood will be in the:
- Framing (ie. what you don’t see)
- Wall/Ceiling cladding
For the purposes of this blog we’ll be looking at the benching (what you sit on) and the wall and ceiling cladding, as it’s what is most important.
What properties does your sauna wood need to have?
There are a couple of properties that a sauna needs to have in order to make it effective, and worth the money. It needs to:
- insulate well
- remain cool(ish) to touch
- remain the same size (ie. not shrink)
- be durable
- be cost effective
And of course, it needs to look good (yes, even if it’s hidden away in a cupboard).
Softwood vs hardwood. Which one should you use for your sauna?
Have you ever sat on a leather couch on a hot day?
Then you’ll know that some materials heat up more than others.
Saunas reach temperatures of up to 80/100 degrees Celcius.
While wood is a great insulator (which is essential for keeping a sauna hot), some types of wood conduct the heat too well and the surface will heat up (it will always heat up a little but we don’t want it to be to a dangerous level)
So, it’s essential that you use a wood that will still be comfortable to sit on when the sauna is at full temperature (especially if it is going to be running for a while).
This is usually down to wood density, and that is what retains the heat.
Hardwoods tend to have a higher density than softwood, as they are, as the name suggest, harder. No prizes for guessing that.
So, in terms of durability you might think that hardwood is a winner. But, due to this density hardwood can become VERY hot to touch. Making it uncomfortable and potentially dangerous to sit on.
After the first thirty minutes or so, it is likely that the walls and benching would become too hot to sit on.
So this rules out a lot of hard woods such as Mahogany, Oak, Beech and Walnut or Teak for saunas (they are also most likely cost prohibitive).
Some hardwoods such as Alder and Aspen have a lower density and offer a good compromise between durability and heat conduction, so are used in saunas.
However, more often than not, softwoods with a good durability are used to build saunas such as cedar, spruce or pine.
How do you make sure the sauna wood doesn't shrink or crack?
One of the most important things to consider (and something that people who go and buy their wood from B&Q skip) is that the wood in a sauna needs to be kiln-dried.
Saunas are heating upwards of 80 degrees Celcius, in an almost 0% humidity environment.
As it heats up, any moisture in the wood is drawn out. Wood is a pourous and fickle little thing, and it will contract as expand as this process happens.
If it happens to much your wood will split and crack.
Standard wood has a moisture rating of approximately 14%. Kiln-dried wood is slowly heated, to reduce the moisture content below 9%.
This means that there is less moisture to move around when you heat the sauna, and the wood is less likely to crack and damage.
It’s very important the wood you use for your sauna is kiln-dried.
Should your sauna wood be knot free?
The answer for this depends on whether you are looking at he cladding or benching.
For the cladding the answer doesn’t matter much. However most people like a finish with limited knots. Wood with knots can be more susceptible to cracking. And you should make sure that there is a low sap content, as this can heat and burn and stain, which can be unsightly and a hazard.
However, when it come to benching you will want a wood with no knots. This will ensure less splinters or abrasion to the skin.
Which wood do we use for your sauna?
So, what do we use?
Firstly, for the cladding and ceiling we have a couple of different options depending on availability and budget, but we usually use tongue & groove:
- Aspen, OR
- White pine
Regardless of what we use, we always buy our timber directly from Finland, and we always use sustainably sourced, Scandinavian timber.
Sustainably sourced means that for every one tree felled, other seedlings are planted. And care is taken to ensure the natural habitat and environment for the wildlife is not disrupted.
For the benching we always use Obeche. It is a hardwood, but it’s very popular in benching as it’s highly durable, knot & splinter free (so will not catch your legs or back), has a low resin content (so less sap to heat and burn) and remains cool to the touch.
Should you DIY your sauna?
There are always some people who wonder about DIY-ing a sauna – it’s why we often get asked about what type of wood we use.
And DIY-ing a sauna is totally possible if you have the skills and the time.
But there are a couple of things to consider…
Firstly, it’s still pretty expensive to DIY your sauna.
Unlike some things that can work out A LOT cheaper, building a Sauna is still pretty expensive even if you do it yourself.
Sure, it will be cheaper than if you hire someone to do it. But the cost of the materials are still pretty high. Remember it’s not just the wood you see. It’s framing, insulation, foil, electrics, your door and your stove. And if you are not able to buy these at trade prices, then the material cost will still be fairly high.
Plus, there is the time consideration.
If you buy a sauna from us we will be in and out in an average of three days (depending on size) and you’ll be left with a fully functioning, ready to use, sauna.
If you are building a sauna in your spare time, without the necessary skills and experience then it will likely take you a lot longer.
So yes it’s possible. But doing it on the cheap is not advisable, and often not possible. Plus you’ll likely spend a lot of time on it still.
If you do opt for DIY make sure you buy the right wood for your sauna, or that could be an expensive mistake.
We do offer material sales, so get in touch if you would just like to buy the wood and stove.
As you might have guessed, the wood in a Sauna is kind of a big deal.
It literally makes up the bulk of your sauna so it’s important that you chose wisely, and don’t get sucked into buying any old wood.
We recommend that you use sustainably sourced softwood, that will give you a balance between durability and suitability for sauna use.