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Water & Rot Resistant Timber Species: The Best Types to Choose & Finishes to Apply

Don’t let a little moisture dissuade you from timber. Wood can provide a beautiful, natural touch, even in places where water might be encountered.

As it’s a natural, porous material, wood can be susceptible to rot and decay if it’s overexposed to moisture. The wood can swell and shrink depending on humidity, which may lead to warping and cracking. Given the weather in Britain, this is certainly a consideration!

However, not all woods react the same way when exposed to moisture. By choosing the correct species of wood and applying an appropriate woodcare finish, you can have some exceptionally waterproof wood on your hands — whether you’re working on decking, cladding, fencing, outdoor furniture, a bathroom — or even a boat.

A close up on a recently sealed deck after summer rain. Water beads up in reflective pools as the sun begins to shine.

The best water resistant wood types & species

Iroko, Oak, Western Red Cedar, Cherry, Maple and heat-treated woods are just a few examples of timber that boast excellent dimensional stability and high resistance to shrinking and warping in the face of moisture. To maximise their performance, these woods can be further treated with a sealant.

Starting with external woods and then moving indoors, let’s explore these species in a little more detail, before touching on some finishes for your wood. All of those we select in this guide are commercially available in the UK, unlike some recommendations in guides you might find elsewhere. So, you can be sure of it being a realistic option for your project when you enquire.

Iroko (and other African hardwoods)

Because of all its natural oils, teak is generally considered the most naturally water resistant wood — but it’s not really particularly affordable, sustainable or easy to get your hands on.

So, if you’re looking to mimic the luxury and opulence of teak (at a fraction of the price), why not choose a wood that goes by the nickname ‘African teak’? Iroko is a highly durable, dense wood, resistant to swelling, shrinking, warping and cracking. It also finishes well.

A mainstay of boatbuilding — testament to its water resistance — Iroko has another well-earned moniker: the Rolls-Royce of decking. It’s also commonly used for fencing, flooring and furniture projects.

You’ll find that many other types of African hardwood are equally adept at resisting water. Suiting your project might be the dramatic ultra-dark look of Wenge, or to make a real statement, look no further than the inimitable, eye-catching stripes of Zebrano.

Oak

Generally speaking, heavy woods provide superior water resistance compared to more lightweight options. At around 675kg/m³ and 755kg/m³ density respectively when dried, this certainly applies to European Oak and American White Oak. Species of oak tend to finish very well, too.

Species of oak generally finish very well and are highly resistant to absorbing water, guarding against warping. Colour variation is a hallmark of oak, but expect a timeless light tan to medium golden brown.

This hardwood has been around for as long as humans have been building with wood. It’s not hard to see why. Oak is popularly used for furniture (inside and out), flooring, cladding, decking, timber-framed garden structures, construction and even boat frames.

A stylish oak gazebo.

Western Red Cedar

The popularity of Western Red Cedar cannot escape mention. Often recruited for cladding and fencing projects, its warm, alluring reddish-brown hues are eternally popular. It’s a wood that ticks the two important boxes: visually outstanding and technically exceptional.

Despite being lightweight, Western Red Cedar has a low shrinkage factor — superior to the vast majority of fellow softwoods — and is particularly resistant to warping and checking when properly installed. Also, because the wood has natural oils, it repels insect and fungal attack, making it extremely durable and decay resistant (even without treatment).

Since the wood is pitch and resin free, cedar finishes very well. In fact, we’ve written a full guide on the treatment options for yours!

If you’re looking to make a saving on your project but still want a wood that’s durable when faced with the wet, Alaskan Yellow Cedar might be up your street, popular for cladding and fencing. Not only does it share many of the same durability properties of Western Red Cedar, but can closely resemble its beauty when treated with a stain.

A designer outdoor space making use of Western Red Cedar cladding.
A stylish exterior slatted fence made of Western Red Cedar.

Heat treated Ayous (and other modified timbers)

Some of the most exciting, innovative new timber products out there are those that have been modified. This process improves the durability dimensional stability of the wood, making it less prone to the damage associated with water.

On trend at the moment are the exotic medium-brown tones of Thermo-Ayous, a popular cladding choice. Be sure to also check out Thermo-Tulipwood, a beautiful clear-grade option, as well as ThermoWood’s tropical dark brown tones. These types of heat-treated woods are not only durable but an eco-conscious choice.

A building stylishly clad using Thermo Ayous wood.

Douglas Fir

A highly resinous softwood, Douglas Fir naturally defends against the wet, with its resistance to expanding and contracting bolstered by a water-repellent finish. With a versatile yellowish-brown colour, it also looks mighty fine whilst doing so — and often comes in a cheaper price than other woods.

Cherry

Moving onto woods that are more at home inside, the beauty offered by cherry’s rich reddish colour is matched only by its exceptional moisture resistance — it’s a fantastic wood for resisting warping and shrinking; ideal for humid environments where changes in temperature could cause warping problems.

Colour and appearance of American Cherry wood.

Maple

A perennial favourite of home improvers, maple’s creamy white and pinkish brown hues slot seamlessly into almost any architectural vision. Packing in a dry density of 705kg/m³, the wood is very hard wearing and does not easily absorb moisture — but be sure to give it a treatment.

It’s particularly popular for furniture and flooring, especially in Scandi-inspired interior spaces. The wood’s tendency to have unique figuring — such as tiger stripe, birdseye and quilting — only adds to its character.

A stylish, contemporary kitchen making use of maple wood for countertops and tables.

Walnut

This is another dense choice that adds a classy, dramatic look to a darker-themed space, or for contrast in an airy room. We wouldn’t recommend walnut outdoors, but it’s fantastic for interior furniture, floors and countertops that might need to withstand some water. A well-chosen finish can practically seal it from any moisture-related warping and checking.

Colour and appearance of American Black Walnut wood.

The best products for waterproofing your wood

For maximum moisture protection, even the most water resistant wood types can benefit from a finish. The type of finish you choose will usually depend on whether the wood is indoors or outdoors.

Waterproofing your wood for outdoor use

There are many excellent products available, but be sure to choose a finish that penetrates the surface of the wood for a long-lasting finish, rather than one that risks forming a film. For woods intending to be used outdoors, we’d recommend a product from the Owatrol range.

  • Owatrol Seasonite — this product is specially designed for wood in its first year of use to prevent damage associated with excess moisture. A water-based, colourless treatment, it prepares the wood for a recoating after around 6–12 months of weathering with another finish. A great solution for that first sealant application.
  • Owatrol H4 Wood — this is a hydrophobic (water repellent) finish that will seal the wood from water. This product is completely clear, having no immediate impact on the colour of the wood. When used outdoors, it will allow the wood to weather naturally to a silvery-grey, whilst protecting from water damage like splitting, cracking and warping. Perfect for those who want the natural, on-trend grey rustic look.
  • Owatrol Textrol HES — this is a powerful, penetrating oil-based sealant for wood. This product is available in a range of shades depending on your aesthetic preference. It provides a matt-sheen oil finish.
  • Owatrol Aquadecks — a penetrating, water-based finish that provides a long-lasting protection against moisture by saturating and stabilising the wood. It is suitable for new or weathered wood and, like Textrol, is available in a range of tints and leaves a rich, matt finish.

All of these products can be applied to dry wood with a brush, roller or airless sprayer, but if time permits, we’d always recommend a brush for the best results and most even application. Allow the wood to dry completely and be sure to check the product manufacturer’s guidelines during the entire treatment process.

Reapplication timelines can vary depending on the product, but are typically required every couple of years. This can vary depending on the exposure your wood has to water, the sun and even salt spray (if you’re in a coastal area).

Waterproofing your wood for indoor use

If you’re looking to seal some wood internally, a wood oil will do a good job. Products containing danish, linseed, teak and tung oil are popular choices for a beautiful, waterproofed finish.

Many of the internal wood finishes you’ll find commercially available will have a mixture of oil, polyurethane and mineral spirits to improve the application process and drying times. Be sure to follow the manufacturer’s guidelines for the best result.

A man applying a protective finish to a wooden table.

Planning a timber project? Need some more advice?

Home improvers, architects, specifiers — we’re here to help. As a leading UK timber importer and merchant, we source over 20 species of hardwoods from across the world and a range of clear-grade softwoods.

As well as a range of quality sawn timber, we offer cladding, fencing and decking, all machined on-site from kiln dried stock and ready to go for your next project, however big or small. For treating and sealing your wood, we also offer the full range of Owatrol woodcare finishes.

As a third generation family business, we pride ourselves on unbeatable customer service, top-notch quality products and flexibility, able to select timber to specification for your next job.

The moment you enquire with us, you’ll be assigned a project handler to guide you through the entire process, from ironing out finer details through to the delivery of your products. Whatever you’re working on — some outdoor furniture, decking, cladding, a bathroom, garden room or even a boat — our team’s on hand to help.

Drop us a message using the button below. You can also reach us through our website contact page, by phoning 01765 640 564 or by emailing sales@duffieldtimber.com.

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