DIY Sauna Door: A Step-by-Step Guide To Building It From Scratch

When it comes to creating the perfect Finnish sauna experience, the door plays a crucial role.

In fact, from keeping the heat in and the cold out to improving aesthetics and helping with sauna venting, sauna doors do it all. 

But if there’s one question that patrons often ask me, it is whether or not they can build a sauna door by themselves. 

Now, being a sauna installation expert myself, I can tell you that a DIY sauna door project is indeed doable. Moreover, do it right and it can make all the difference to your sauna regimen. 

In this blog, I’ll explain each step of building a sauna door. Also, I will tell you how to design the door for optimal heat, safety, and aesthetics.

So, let’s get started. 

How to build a DIY sauna door?

Building a sauna door by yourself might seem like a big task, and I get it. But let me tell you that with the right materials, tools, and steps, it’s totally achievable.

Moreover, even first-time DIYers can build a well constructed sauna door that retains heat, keeps you safe, and adds a custom feel to your enclosure.

Curious how? 

From the exact tools and materials I use on my own sauna installs to all the steps I follow, I’ve detailed them all here. 

Here’s how to build a sauna door: 

First, get the right materials and tools

Before you can start building a sauna door, you’ll need to get all the necessary materials and tools first. 

You see, getting your materials and tools ready ahead of time is the easiest way to avoid frustration mid-project.

And to that end, here are all the things you should always keep on hand when building a sauna door: 

A. Materials

• Wood (preferably Cedar)
• Rigid foam insulation
• Glass panel (optional material to bring in natural light or keep an open feel)
• Hinges and handles
• Sealant (preferably silicone)

B. Tools

• Measuring tape
• Saw (circular or table saw)
• Drill & screwdriver
• Clamps
• Wood glue
• Sandpaper (120 to 220 grit for a buttery-smooth finish)

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Second, follow the right steps to DIY sauna door installation ​

Now that you’ve got everything ready, it’s time to get hands-on and start building. And to help you out here, I’ll walk you through each step just like I do on my own installs. 

I will explain the why behind every action so you’re not just following instructions, but also understanding the process. After all, every step is key to making sure your sauna door performs like it should. 

Here are all the steps to build sauna door DIY: 

Step 1: Measure the sauna door dimensions

First thing first, you need to get your measurements dialed in. This step is the foundation for everything that follows.

Sauna doors aren’t your average household doors. Instead, they're narrower and slightly shorter, with sauna door size usually ranging from 24" to 30" wide and 72" to 80" tall. 

Why the difference, you might wonder?

Well, it's all about heat retention and efficiency. And a smaller opening helps maintain that cozy consistent temperature that makes saunas so effective.

You can start by measuring the rough opening from the stud-to-stud width and floor-to-top framing height.

​Here, I suggest  measuring in at least three places for both height and width (top, middle, bottom). That’s because sometimes the framing isn’t perfectly square. 

Also, if your measurements vary a bit, go with the smallest one to ensure a snug fit. 

Pro tip: Don’t forget to account for any flooring that might add to the final height.

Step 2: Cut the wood panels

Having precise measurements on you, it’s time to get your hands dirty and let your craftsmanship shine. 

Here, you’re going to need two main sauna wood panels, one for the interior side of the door and one for the exterior. 

Now, use your measured dimensions to mark and cut the panels accordingly. A good practice here is to double-check your marks before cutting or measuring twice, cut once, as they say. 

Personally, I prefer using a circular saw with a fine-tooth blade for cleaner cuts and less splintering.

This is also a good time to decide whether you want a simple slab-style door or if you’d like to add any panel detailing. 

However, keep in mind that the more pieces you add the more chances there are for heat to escape. Meaning it's better to keep it simple for optimal heat retention. 

Pro tip: Lay your boards flat and let them acclimate to the room’s humidity for a day before assembly. This will help prevent any future warping or shrinking once the sauna gets cooking.

Step 3: Add insulation

This is the step where you really start to transform those cedar panels into a functional heat-retaining sauna door. 

I have come across a lot of DIYers who underestimate how important insulation is for a sauna door. 

But as someone who’s spent a lot of time sweating it out in all types of builds, let me tell you this step is critical. That’s because without proper insulation, your sauna will struggle to maintain temperature and your heater will work overtime.

For sauna insulation, I always go with rigid foam board insulation, specifically polyisocyanurate or extruded polystyrene (XPS). These materials are lightweight, easy to cut, and have high R-values, making them excellent at retaining heat.

​Here, you’ll want to cut the insulation so that it fits snugly between your cedar panels with no gaps. Also, you can use a utility knife and a straightedge for nice clean cuts and then test-fit everything before moving on.

Step 4: Assemble the door

Now comes the part where everything starts to come together. And honestly, it’s one of my favorite steps. 

We’re taking those beautifully cut cedar panels and the insulation core and turning them into a solid functional sauna door. 

The goal here is to create a sandwich with cedar on the outside and rigid insulation in the middle. And just like any good sandwich, you want it to hold together firmly and evenly.

You can start by applying a high-quality wood glue around the perimeter of the insulation board and across the flat surfaces of the cedar panels. Here, I suggest you use waterproof heat-resistant wood glue since this door is going to face some serious steam and temperature swings. 

Thereafter, carefully align all your layers ensuring the door looks even and doesn't interfere with the way it swings and seals.

Now, once everything is in place, clamp the entire assembly together. Even if you don’t have long bar clamps or panel clamps, you can improvise by wrapping ratchet straps around the door tightly. 

At the end, wipe away any glue squeeze-out with a damp cloth before it dries and let the whole thing cure as per the glue manufacturer’s instructions. 

Once dry, you’ve officially built the body of your sauna door. 

Pro tip: Sauna doors should always open outward for safety reasons.

Step 5: Install the glass panel (optional)

Although adding a glass panel is totally optional, it really elevates the look and feel of your sauna. And if you’re anything like me, being able to see the warm glow inside the sauna as it heats up adds to the anticipation. 

That said, installing a glass panel requires precision and patience. But it’s 100% doable if you follow these steps.

First, decide on the size and placement of your window. Most people go for a rectangular pane vertically centered on the upper half of the door. 

Also, you'll want to use tempered glass since regular glass won’t hold up to the temperature changes and could become a safety hazard. 

Once you’ve got the cutout ready, dry-fit the glass to make sure it sits nicely with a little bit of space around the perimeter for expansion.

To install it, you can run a bead of high-temperature silicone sealant around the inner edge of the opening. Follow this by carefully pressing the glass into the opening and then secure it with cedar trim pieces on both sides of the door. 

Pro tip: Let the silicone cure for at least 24 hours before exposing it to any heat or movement.

Step 6: Attach hinges and handle

Now that your door is structurally sound and looking sharp with a glass panel, it’s time to hang it up. This is the step where things start feeling real. 

First up, decide which way your door will swing and install the hinges accordingly. Mark your hinge positions, one about 7 inches from the top, one 11 inches from the bottom, and a third in the center. 

Pre-drill your holes to avoid splitting the cedar and then secure the hinges using corrosion-resistant screws. Here, you’ll want to make sure everything is level, so have a friend help hold the door up (or use shims) while you attach it to the frame.

As for the handle, I suggest using a wooden handle, both inside and out. That’s because metal can get scorching hot in a sauna. 

Step 7: Seal the door

At this point, your sauna door looks great, swings like a dream, and maybe even has a beautiful glass panel. 

But there’s one more piece to the puzzle: The seal. 

You see, a properly sealed sauna door is absolutely essential to maintaining heat and humidity inside the sauna. 

So, let’s talk weatherstripping. 

Start by applying the weatherstripping around the inside edges of the door frame where the door meets the jamb. And be sure to press it firmly in place so it sticks evenly and doesn't interfere with the door’s swing. 

I usually apply it in one continuous piece around the top and sides, but I avoid putting it on the bottom edge unless absolutely necessary. 

Once the weatherstripping is in place, test the fit by closing the door slowly and check for any resistance. If it feels too tight, adjust the strip or switch to a thinner profile. 

You want the door to close with a gentle, solid "thunk", not a struggle. And while you’re at it, this is a good time to check for any light leaks. 

​Step 8: Finishing touches

Alright, you've done the heavy lifting. Your door is built, sealed, and hanging strong. 
However, we’re not quite done yet. 

This final step is all about refining and protecting your work so it lasts for years, looks beautiful, and feels like something straight out of a high-end spa.

First up: Sanding

Grab a sanding block or an orbital sander and go over every surface, edge, and joint. I like starting with 120-grit sandpaper and finishing with 220 for that smooth buttery finish. 

Focus on any sharp corners or glue spots, especially if you had any squeeze-out during the glue-up phase. 

You see, smooth edges aren’t just about looks as they prevent splinters and give a more comfortable touch.

Next: Sealing or staining

Now, this is a crucial procedure and you do not want to use any varnishes, polyurethanes, or conventional stains that release fumes when heated. 

What you want is either a natural oil like tung or a sauna-specific wood treatment designed to protect without off-gassing. In fact, some people even leave the wood raw, which is totally fine too since cedar is naturally durable and beautiful on its own.

Apply the finish with a soft cloth or brush, working in the direction of the grain. Let it soak in and then wipe off the excess and allow it to cure fully before using the sauna. 

Finally: Testing

Open and close the door several times. And as you do so, listen for squeaks, feel for drag, check for sealing. 

Also, fire up the sauna and sit inside for a few minutes to check for drafts and fogging around the glass or hotspots. 

Looking for more DIY sauna ideas like this? 
You can go through my blog: A Complete Guide To DIY Sauna Tent. 

Frequently asked questions about DIY sauna door installation

Can you use other types of wood besides cedar?

You absolutely can,
But from experience, I always lean toward cedar. It just performs better in sauna environments. That said, other options like hemlock and spruce are also commonly used, especially in commercial saunas or when you’re working within a tighter budget.

Is a glass panel necessary?

No, it is totally optional. 
However, if you’ve got a smaller sauna or you want a more open spa-like feel, a tempered glass panel can make a huge visual impact. It lets in natural light and helps you keep an eye on things without opening the door. 
Some people prefer total privacy and go with a solid wood door, and that’s great too. So, it’s all about your vibe. 

How do you ensure the door seals properly?
The key here is a combination of things: Your door needs to be square and your hinges must be secure and aligned. 
Also, your weatherstripping has to be top-notch. 
I always test my doors by closing them slowly. 
You can also shine a flashlight from inside the sauna at night and look for light leaks. And if you see gaps, adjust the door or add new weatherstripping.

Can you paint the sauna door?
You can, but I always caution people to avoid painting the interior side of the door. 
Paint, especially standard interior or exterior types, can release VOCs or volatile organic compounds when heated. And you don’t want to be breathing that in during your sauna session.
If you really want to paint the exterior for aesthetic reasons, make sure you’re using a heat-resistant, low-VOC paint, and give it ample curing time before exposing it to heat. 

Conclusion

As you can see, a DIY sauna door is something you can absolutely do right. All you need is the right materials and correct installation steps. 

I’ve built and installed countless sauna doors. And I can tell you confidently that you can build sauna door DIY without hassle. 

Got more questions or need to get a professionally installed sauna in your home? 
You can get in touch with us!

At Steam & Sauna Experts, we are seasoned sauna installation experts with over a decade of experience installing top-of-the-line saunas across South Florida. And we’ve got all your home sauna needs covered on a budget.