A sauna renovation begins with a vision: imagine what your ideal sauna would look and feel like, and consider the features you want it to have. Once you have a clear picture of your dream sauna, it’s time to take measurements. Measure the width, height, and depth of the sauna, as well as the window and door openings. Don’t forget to measure the log, stone, and window surfaces that affect the heating power requirements. This will help professionals select the right sauna heater for your space.

Generally, renovating a sauna in a detached house does not require a building permit or an action notification. Permits are only necessary for demolishing or building a load-bearing structure, or if you’re expanding the bathroom. You must obtain a permit if you’re constructing a completely new bathroom or sauna. In these cases, it’s best to contact the building control services of your local municipality.

If you live in a housing company, you must notify the board of directors before starting any renovation. Housing companies typically require professionals to handle waterproofing and electrical work. Therefore, secure all necessary permits before beginning demolition.

When demolishing an old sauna, inspect the underlying structures and repair them as needed before installing new surfaces. Ensure the aluminum paper remains intact and leak-proof. If it’s damaged, check for underlying issues. If everything is in good condition, proceed with installing the new surfaces.

Glass walls are a popular choice in sauna renovations and can be installed based on the wall and door structure. During demolition, a professional should assess feasibility. If necessary, reinforce the existing wall for added support.

Over the past few decades, construction technology has advanced significantly, offering new solutions and materials to replace older ones. While urethane-based insulation materials have been available for some time, they weren’t commonly used in saunas built 20-30 years ago.

The advantage of urethane sheets as insulation is their thinness. For instance, a 30 mm urethane sheet is equivalent to 80 mm of mineral wool insulation. Replacing the old insulation can save up to 5 cm in wall thickness, which is especially beneficial in smaller spaces. Waterproofing products have also improved significantly, reducing the risk of water damage.

Please note that if you replace a woodburning stove with an electric heater, the old masonry flue cannot be paneled over or have benches installed on top of it if the flue remains in use. Often, there may be a fireplace, iron stove, or similar appliance on the side of the wall, connected to the same flue. While the masonry can be tiled over, nothing can be affixed to it. Always check with the local fire authority to ensure compliance with safety regulations.

Electrical work in a sauna must always be performed by a licensed professional. It’s essential to consult an expert electrical designer well in advance when planning your sauna’s electrical setup. During a sauna renovation, relocating the sauna heater is typically unnecessary. However, if you’re using an electric sauna heater, repositioning is generally possible if desired.

Plan electrical wiring modifications early in the renovation process. Electricians place supply current cables within the wall insulation, so address these considerations during demolition. Once surface materials are installed, modifying the electrical setup becomes impossible.