The Best Decking for a Hot Tub Stands Up to Moisture and Chlorine

The best decking for a hot tub is moisture resistant

Hot tubs require decking that is well protected from their salts, chemicals, and moisture.

I spent some of the best years of my life living on the coast, building and repairing houses when I wasn’t enjoying the salty air. Almost every vacation rental I worked on had a hot tub on the deck, and amazingly, some of them had more than one! I’d frequently notice that the decking on these houses was in great shape on every part of the deck except around the hot tub.

Having a hot tub is one of the great treats in life, but the unfortunate truth is that splashing and the treading of wet feet can lead to a very wet deck. This water, along with the chemicals in it, isn’t good for a wood deck, and will cause your decking boards to deteriorate much more quickly than they would otherwise. Most wood decks require plenty of TLC to keep damage from moisture at bay, but there are alternative options that play much better with hot tubs than traditional wood does. The best decking for a hot tub looks great no matter how often you use your hot tub, and doesn’t require a lot of effort to keep it that way.

How Hot Tubs Can Harm a Deck

Whether they sit right on top of the deck or are recessed within a cutout in the deck, hot tubs frequently bring all sorts of challenges. Most of the hot tubs that I’ve dealt with have been placed on top of decks, so my advice here will be specific to that situation, however, many of the difficulties I’ll describe apply to both arrangements.

  • Trapped Moisture: Whether through splashing or through evaporation and condensation, moisture inevitably finds a way to collect precisely where you don’t want it–just underneath the hot tub where it’s difficult to protect the deck. Over time, the boards under and around the hot tub begin to take on water and break down.
  • Salts and Chemicals: The salts and chemicals used to keep hot tubs hygienic aren’t friendly to wooden decking.  With salt water tubs, wood fibers draw the salt water inside and when the water evaporates, salt crystals form disrupting the wood’s cells.  Chlorine breaks down wood proteins, and although the chlorine in hot tubs is less than what is found in bleach, over time it will start to have an effect, and can sometimes alter the wood’s color. An ozone-based system may have less of an effect on your decking–if you need help deciding what system to use to keep your water clean, there are resources available such as first-time hot tub buyers’ guides that lay out the options for you.
  • Weight: A hot tub filled with water and people is very heavy–they generally weigh several thousand pounds. The substructure beneath the deck needs to be able to support the weight. Once you’ve determined that your deck can bear the weight of a fully filled hot tub, you still have to take into consideration how that weight, and the moisture from splashed water, can damage your deck’s boards over time.

How to Protect Your Deck from a Hot Tub

There are a few simple and effective steps that can be taken to protect a deck from the negative effects of a hot tub. While making wise design choices up front is often the easiest solution, all of these solutions can also be implemented after the fact:

  • Restoring Drainage and Airflow: Drainage is something that is set up when the hot tub is first installed, but over time leaf litter and other debris can work its way into the space between the hot tub and deck and block water and airflow.  Regular cleaning around your hot tub will keep the air flowing, allow trapped moisture to dry, and will extend the life of the deck underneath.
  • Special Paints and Sealants: Using a marine grade coating on your decking boards (I like marine grade paints) can be a little pricey, but if you have the money upfront, it is well worth it. Obviously, it’s much easier to do this before the hot tub has been installed. I am not a big fan of attempting to prep a surface for painting while playing musical deck furniture.
  • Fully Capped Composite Decking: A high-quality, well-protected composite decking board will perform just as well as a wooden board protected by a marine grade paint or sealant. The best lines of composite decking are protected with a sturdy enhanced resin cap, which seals the core of the board off from moisture and chemicals.  Fully capped composite decking won’t require repainting, either, and they come in styles that look like real wood, or like rustic-style reclaimed decking boards.

 The Best Decking for a Hot Tub? High-Quality Composite

Most people seem to enjoy having to do less maintenance rather than more maintenance–at least I do! As such, when I come across a deck that is having trouble with its hot tub or I get to plan for the imminent arrival of a hot tub, I typically suggest using high-quality, fully capped composite decking for the decking surface. It simply takes up less time and effort over the long haul than wood and is more reliable and better looking than various jerry-rigging schemes to prevent wood from deteriorating.

It’s important to note that not all composite decking is made to the same standards. Some decks are only capped on top, which can cause all sorts of trouble when excess moisture from the hot tub gets under or between the boards. And not all fully capped boards perform in the same way, either. Some caps have proven to be weak, either peeling off or being prone to gash or scratch easily, another way in which moisture infiltrates the boards. With that in mind, seek out a board with as strong and durable a cap as possible.

Among the better fully capped decking boards I’ve worked with is Infinity decking, produced by Fortress Deck. I direct people to the Fortress Deck site because their composite has a capping made of tough, rubbery, enhanced resin. Not only does it do a good job of keeping moisture, salts, and chemicals out of the decking board, it also gives the boards some traction, making them slip resistant as well as moisture resistant. In addition to decking materials, Fortress also produces a full line of building materials which is also well worth looking into if you’re in need of other high-quality, weather resistant products like fencing and railing.

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