This is a complete guide to non-toxic decking – types, materials, additives, and brands.
For most people, the main choice is between composite decking and solid wood decking. For the chemically sensitive you will have to get samples yourself of the decking materials as well as the stains needed for real wood – as this choice is very individual.
The long-term benefits of not having to do any maintenance on composite decking can outweigh the initial concerns.
There are also some more unusual options to choose from like aluminum decking.
Composite Decks
Material Make Up
Composite decking material is generally made from a mix of wood fibers and plastic. The plastic is polypropylene (PP) or polyethylene (PE), mixed together with wood dust, pigments, UV inhibitors, and usually borate. This plastic is usually recycled, like from plastic grocery bags.
If you do well with polyethylene or polypropylene that should be OK for you, but ask to see a sample of the ones available near you and see if you can get a sample of one that is as newly manufactured as the one you would buy. These plastics do have a little bit of odor.
Most of them now are capped in an outer layer of plastic. The type of plastic is not always specified, but you should ask, especially if you are avoiding PVC vinyl.
Additional Chemicals During Install
Glue is not used to install composite decks, but you are meant to seal the rough edges of some brands with a lumber wax – be sure to tests out the product that the company recommends if you are super sensitive.
Trex does not recommend using a lumber wax, sealant, or any other glue or sealant in the installation.
The only maintenance needed for most brands is soap and water.
Mold Prone?
Many have reported their composite decking becoming prone to growing mold. Some experts have recommended only going with brands that are capped with plastic on all sides to help prevent this issue. Brands with bamboo fibers might also be less prone to mold since the fibers do not clump as much.
Brands
Capped composites like Trex Transcend or TimberTech Earthwood Evolutions use a traditional composite decking core with an added plastic polymer cap.
Trex is the most well-known brand of composite decking made with recycled bags (PE), and it is capped with an unspecified type of plastic, which they said is not PVC.
Dura-Life brand is a blend of polypropylene (about 20 percent), recycled wood and plastic (about 25 percent), and hardwood flour (about 55 percent). Dura-Life planks have a polypropylene cap outer shell covering the extruded composite core.
I have heard from really chemically sensitive folks who did well with Dura-Life. I sampled this one and I would describe the odor as a fairly mild glue odor when sniffed directly.
A non-wood composite, Lumberock Premium Decking, offers a line of decking materials made from a combination of plastics and mineral materials instead of wood fibers. You might want to check that one out if you are sensitive to the natural odorants of wood.
Wood-based composites do still retain some wood odor. For example, a cedar composite that I tested definitely smelled like cedar. The ones I tested (Trex, Dura-Life) also have an odor that I would describe as a light glue odor.
Cost
A Trex deck typically runs from $9 to $16 per square foot.
Maintenance
Non-toxic cleaning products that won’t damage composite decks are here.
PVC Decking
Material Make Up
Some PVC decking is 100% plastic and some is a composite decking made of PVC and wood fibers.
Many chemically sensitive folks like to avoid PVC since it tends to be higher in offgassing, odors, and added chemicals, however, the odor here of the wood-PVC composites is fairly mild and in my experience was milder than the composites above.
These are some brands that make PVC decking which generally look the same from the atop view as the non-PVC composites.
Additional Chemicals During Install
With solid PVC boards you would not need to seal the edges.
Mold Prone?
Mold growth would only be superficial on solid PVC boards since it cannot grow in the material. With composite products, if they have real wood in them they likely are prone to mold to some degree, especially if not capped on all sides.
Brands
AZEK and TimberTech AZEK products are made from a solid PVC which they claim is highly resistant to stains, scratches, splits, mold, and mildew.
Despite being PVC, I found that the TimberTech AZEK only had a slight odor when new (when sniffing it up close) – less than the odor of TREX and Dura-LIfe composites, in my opinion.
TimberTech Pro and TimberTech Edge are composites – a mix of wood fibers and plastic PVC, capped with PVC. (Not capped in PE as some websites say).
Envision Composite Lumber with no natural wood fibers and PVC. Some lines are capped (in PVC) and some are not.
EverNew by CertainTeed line includes decking materials that are either solid vinyl or a blend of PVC vinyl and wood flour.
Fortress Apex PVC Decking’s “foam core” is cellular PVC reinforced with bamboo. The boards are encapsulated in an acrylic polymer.
Fiberon company makes surface decking, railing components, and fencing products that are made from a solid PVC “Permatek” outer shell bonded to a wood composite core.
Cost
Azek is 2-3 times the cost of Trex composite.
Maintenence
Non-toxic products that won’t damage vinyl decks are outlined in this post on deck cleaners.
Real Wood Decks
Pressure Treated Decks
Pressure-treated wood for decking is usually pine, treated with copper and quaternary ammonia. The ammonia will offgas from the pine, but for those who are extremely sensitive, they can have challenges with this when it is fresh.
I have also seen pressure-treated wood treated with flame retardants, though this is not the norm – examples: wood from Hoover and FRX.
One other challenge with pressure-treated wood is that it can not be sealed or stained for about 6 months when it is new unless it’s already been dried out.
Cedar Decks
Cedar is the most common natural wood option and it’s good for those avoiding toxins since it doesn’t need pressure-treating (with copper-quats) like pine does.
Cedar does have a rather strong natural odor which bothers some people with extreme chemical sensitivity. My post on the odorants of wood looks more at this issue.
Although it doesn’t require pressure treating you should stain it every few years, so you will have to find a sealer you can tolerate. My post on deck sealers goes through the options.
Usually the base structure of decks is made from pressure-treated wood.
Redwood is another naturally rot-resistant wood used for decking in North America. Like Cedar, it is not pressure treated and does require a sealant.
Cedar and Redwood are pricier than pressure-treated pine.
Ipe Decks
Ipe is a wood species for decks that could be ideal for those avoiding toxins.
Though it’s quite pricey, pricier than Cedar and Redwood, it does not require sealing (or pressure-treating). Though adding a sealer can help preserve it. You can choose between natural oil options and a very low VOC oil/water hybrid detailed here.
Other Rot-Resistant Woods Used in Decking
Massaranduba, Cumaru, Tigerwood, Garapa, Mahogany, and Teak are a few other naturally rot-resistant tropical woods that can hold up as outdoor decking.
Out of the woods used for decking, Cedar is the highest odor wood and Garapa is the lowest. If you find yourself sensitive to the natural odorants of wood, get a few samples of different species and see how you do.
Non-Toxic Modified Woods
Thermally Modified Wood
Thermally modified wood for decking is treated with heat. This makes it more durable and gives it protection against rot and termites. No chemicals are used in the treatment. It has the smell of smoked wood.
Thermory is a heat-treated wood brand, they say it lasts as long as a tropical hardwood like Ipe.
There is a wax to seal the edges of Thermory. Other than those edges it comes finished and you don’t have to refinish this again if you don’t want to.
Acetylated Wood
Accoya wood is Radiata Pine and Alder species treated with acetic anhydride. The treatment leaves the wood harder, more dimensionally stable, and immune to insects. Some acetic acid is left in the wood and that does leave it smelling a little bit like vinegar.
You can add a finish or leave it unfinished.
Furfurylated Wood
Kebony is another modified wood. Furfuryl alcohol is impregnated into the wood and is polymerized. I’m a little more hesitant to recommend this type of wood due to more unknowns with this chemistry.
Aluminum Decking
Aluminum decking by Nexum is made from powdered coated aluminum. A chemically inert product and certainly the safest one on this list for the extremely chemically sensitive.
The above type is gapless which can help to provide usable area under the deck.
Related:
Non-Toxic Deck Stains & Sealers
Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.
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Bertie says
Thank you for all of your articles, they are really helping me navigate this horrendous illness.
Before I discovered them I had a wood structure built for the garden using pressure treated wood, and now reacting to them structure. Is there anything you recommend me to do? I’m desperate for a structure and all other attempts have failed due to my severe sensitivity.
Corinne says
it depends on what this wood structure actually is. generally I would just give it time to offgas.
Elliot says
I can get untreated yellow pine deck boards from a local lumber yard. In your experience, would applying Vermont Coatings stain to all sides be sufficient to protect untreated wood from rot? Thank you.
Walt says
I have heard ipe dust is toxic. Would you be concerned about buying a house that already has a ipe deck or since it is already installed there shouldn’t be much concern about it?
Corinne says
All wood dust from all species is harmful to breathe in.
Mia Evans says
Thanks for helping me understand that Trex would be the most popular brand of composite decking which uses recycled bags and is capped with other types of plastics. I might want this material for my backyard because of being made from recycled materials. It will be helpful for the environment if I look for Trex deck building company professionals to install them before this year ends.
Nando says
and what happens to the Trex deck once it’s past it’s useful life or if you or a subsequent owner replaces it? It ends up in the landfill for lord knows how long.
Eli Richardson says
I’m so glad you talked about decks and finding a material for ours that’s not toxic. My wife and I are excited to start renovating our house’s backyard. We’d like to install a deck in a few weeks, so we think it’d be beneficial if we read your tips first. Thanks for helping us understand why we should also consider a deck’s maintenance needs before choosing its materials.
Sheila says
Would the aluminum decking not be a good option for those who are also EMF (electromagnetic fields) sensitive? What about concrete patios? Are concrete patios considered toxic or problematic for chemically-sensitive individuals?
Corinne says
I would not expect a deck to cause EMF problems.
Concrete is usually fine.
sc says
I am super chemically sensitive. I used Vermont Coatings clear for my pressure treated pine deck. It was installed 2017, and smelled so very bad. It was many months before I could go in the backyard. Summer heat really helped the deck off-gas. Then by fall I was putting on the exterior Vermont coatings in clear. It had no smell at all. I like the finish. Dew and rain would bead on the surface. I did have to reapply in 2 years. It is a good product.
Corinne says
It’s an unusual product response in that technically it’s one of the lowest odor finishes but there are some of the most extreme you seem to have a bad reaction to what I assume is the whey.
Donna says
If I am trying to build a deck that is the greenest it can be and free of chemicals ..would that be an aluminum deck?
Thank you!
Excellent article!!
Corinne says
A wood deck can be free of synthetics chemicals as well. It’s up to you.
T says
I try to avoid all aluminum as it is implicated in Alzheimer’s and appears in agricultural products, foods, baking pans, and construction materials, for example fiber glass. Aluminum is a very lightweight metal that melts easily if a house were to catch on fire. Because fiberglass is in a lot of construction materials, if there were a fire, you would be breathing in aluminum. I take this into consideration especially because we have an older home and use a wood stove for heating the house. We also cook a lot at home and have five children. A small house fire at any time is not unthinkable. I’d rather be breathing in all natural wood smoke or natural fiber smoke, and I believe we would have a much better chance escaping a house fire and with fewer potential side effects than if plastics and aluminum are mixed in. By the way, shingles are better to vent a house fire, but we did not know that before we got metal roofing. That said, at least an aluminum metal decking is on the outside of a home, and hopefully would be fire resistant unlike smaller aluminum products and materials inside a wooden building.