Secrets You Need to Know When Using Wood in Wet Spaces

It’s almost counter-intuitive, the practice of putting a material like wood—which has issues with humidity and expansion—in a place that's constantly getting wet, like a bathroom, kitchen, or even the exterior of a building. But with careful detailing and a thoughtful selection of proper species, wood can actually be an ideal material for nearly any location, wet or dry. Here, we take a look at five places where the use of wood might seem taboo at first, and we’ll delve into why wood is actually a good choice for that space or location.

Wood Shingles and Siding

You've probably seen wood siding on the exterior of homes before, and if you really scrutinize the practice, it does seem odd. Why put wood on the outside of a building, and not even coat it with paint? How does it resist rot and decay when it's constantly being exposed to rain and snow? The truth is that not all woods are appropriate for exterior siding, but the group of wood species we refer to as cedar is a common exception.

Cedar is actually a group of more than a dozen different species of trees that belong to different families, and they tend to share similar characteristics of being resistant to rot and decay because of the "resins" or "extractives" in the wood, which are naturally occurring chemicals produced by the tree. This means that there's no need to stain, paint, or pre-treat the wood to make it resistant to rot, but the wood does weather and change in color, aging to a more grayish tone as opposed to the reddish or brown tones the shingles start their lives as. That doesn't mean that unpainted wood shingles will never rot, but in concert with appropriate detailing and installation, like overlapping each shingle so that water drains down off the shingle rather than trapping water underneath it, cedar siding can last decades.

Wood Roofing

Using wood siding or shingles on the roof can seem even more counter-intuitive than using wood siding. However, similar principles apply here too: you want to make sure you're using a type of wood that's resistant to moisture, and that the wood is installed or applied in the correct manner. 

Wood roofs are less common than wood siding, but in colonial America, they were the most common type of roofing material. Today, they're still used, especially in projects that want to achieve a traditional-meets-modern feel or in areas where cedar is easy to obtain and relatively inexpensive. Wood roofing is also seen as more sustainably oriented than other materials. This is because wood is a renewable resource and cedar roof shingles have a relatively long life of more than 60 years (when cared for and maintained). For example, if a wood roof does start to exhibit signs of mildew or moss, you can buy exterior spray applications than can be applied to remedy the issue.

Wooden Kitchen Countertops

Compared to more durable materials like stone, wood countertops might seem inadequate and even inappropriate, especially if they’re used around a sink area, where water is constantly splashing over the edge and pots and pans tend to pile up. However, countertops made out of wood like butcher block (a laminated piece of hardwood) have successfully been used for centuries. Wood countertops, whether they’re made of solid wood like large slabs of walnut or a classic maple butcher block, can create a warm, natural feel in a kitchen and can reduce the noise of pots and pans landing on the countertop. 

But that doesn’t mean that all species of wood make for good countertop surfaces, or that there’s little to no maintenance involved. Softer species of wood, like pine, typically don’t make for ideal countertops because of how quickly they dent and scratch. While it's possible to use sandpaper to refinish wood that’s been scratched, refinishing an entire countertop that’s been dented or damaged can be challenging and avoided if harder woods like birch, beech, or maple are selected. Additionally, wood countertops should be oiled once per month if the surface is unfinished, or refinished every five years if it comes pre-finished from the shop. This will protect the wood from most stains and water damage, but it does require frequent upkeep.

Wood Surfaces in the Bathroom

Given the constant humidity in a bathroom, it's probably not most people’s first choice when it comes to selecting a finish for this room, especially when ceramic tiles and other non-porous surfaces are available in a wide range of colors and prices. However, because of its organic, natural appearance and warmth to the touch, as opposed to the cold feel of tile, wood has become a more common choice in bathrooms. 

If wood is used as a wall, floor, or ceiling finish in a bathroom—especially one with a bathtub or shower—you’ll want to make sure you have a fan installed for proper ventilation. This will also protect the wood from warping and reduce the chance of mold or mildew from growing. Another good idea is to make sure that the wood is coated in some kind of sealant, perhaps boiled linseed oil and/or urethane, to protect it further—and make sure you get all the end grains covered too, even if they won’t ultimately be exposed. Experts also suggest applying a layer of tar paper (usually used under roof shingles) before installing the wood for an added layer of ventilation and protection.

Wooden Bathtubs

Finally, we arrive at the biggest mystery of them all: a wooden bathtub. A bathtub made out of wood feels like it should either leak non-stop or swell up so much that it loses its shape. But many cultures across the globe have been successfully producing wooden bathtubs for centuries: the Japanese have used aromatic woods like cedar and hinoki to make soaking tubs called ofuro, while teak and other woods have been employed in tubs in Scandinavian countries.

The trick to making a wooden bathtub work is—like all uses of wood—to make sure that the proper species of wood are selected from the beginning, and that the wood is regularly maintained. Teak, for example, was often used on the decks of ships, and works well as a bathtub material because of its resistance to rot. Most experts advocate for multiple layers of sealant on wooden bathtubs to provide continued protection against the wet-dry cycles that the tubs go through, which can often make the wood more textured than it initially was, causing hair or skin to get stuck in it. 

For wood that's traditionally been oiled rather than sealed, like Japanese hinoki, sealing the wood cuts off its notorious scent, but allows it to constantly dry and then swell, ultimately causing leakage and staining. To avoid this, it’s best to keep the bathtub out of direct sunlight, apply sunflower oil to all of the tub surfaces, and keep the moisture level constant by using a lid or cover over the tub when it’s not in use.