One of the hardest parts of a deck project is selecting the surface material. At this point many people immediately start to think about what color they want their deck to be, but choosing the material can be a harder decision; there are a lot more options out there today than you may be aware of. It’s no longer a simple choice between natural wood or a man-made product. Your choice not only affects the look of your deck, but, more importantly, how it functions.
The goal of this article is to give you a basic understanding of the different decking materials available today and the benefits and drawbacks of each. There are essentially five different material types: natural wood, pure PVC (polyvinyl chloride), wood composite, composite core with PVC cap-stock, and finally, modified wood products. There are a number of different manufacturers for each of these products, and their prices vary depending on style and color. However, aside from some minor variations due to their exact compositions, the materials in each category are relatively similar in terms of performance.
Wood is a fantastic environmentally friendly product. Softwood species like cedar and a variety of tropical hardwoods will all show the natural beauty of a wood deck. People have also been known to install pressure-treated wood (PT) and Fir on decks, but these are not materials we would recommend (in fact, we won’t install them) because PT will splinter and warp over time, and Fir is too soft to hold up to the brutal assault of insects and mother nature.
- Natural beauty: A man-made product simply cannot match the subtle variations in colors and wood grain that are found in natural wood.
- Environmentally friendly: Since wood is a natural product and if the deck is maintained properly will last for many years. The scraps and cut-offs will eventually decompose in a landfill. We keep our scraps, especially the hardwoods, to burn in our campfires. (How decadent it is to toast marshmallows over Mahogany!) There are a wide variety of programs around the world that are dedicated to responsible forest management and ensuring the sustainability of wood products, which often travel fairly long distances before reaching the U.S. market. Programs like the FSC (Forest Stewardship Council) have found ways to document every step of the process from the time the tree is cut to the delivery at the jobsite, but FSC certification has not yet been adopted by all distributors because it can be moderately expensive and complicated.
- Strength and durability: Wood is naturally strong, and tropical wood is very dense. If you choose a tropical wood it will stand up well against scratching and dings. Also, wood can be repaired.
- Color: Wood can be oiled, stained with a solid-body (opaque) stain, or left alone to “silver.” The oils we use can either be clear or slightly tinted. There are a variety of colors of stain that can be applied to the deck, but they tend to cover up some of the natural tones of the wood. When unfinished tropical woods “silver,” they essentially lose their pigment and turn a nice shade of grey. This is purely aesthetic.
- Insect resistant: Since tropical woods are very dense, they are unattractive to insects and pests.
- Needs seasonal maintenance: A wood deck needs to be maintained in order to keep up its appearance and not silver. Maintenance involves washing and seasonal oiling, including completely stripping and reapplying the oil every few years. Solid-body stained decks don’t need to be recoated as frequently (once every two years or so), but there is still maintenance involved. If you let your wood deck silver, significantly less maintenance is needed, but it’s very hard to undo if you don’t like the look.
- Movement with temperature and humidity: Because of its cellular structure, wood is prone to shrinkage, swelling, and movement due to moisture. This is affected by both humidity and temperature. If not installed properly the boards can warp and cup, at which point a repair can be tricky.
- Prone to staining: Spilled foods and other things that are left on the deck will cause permanent stains. Be very careful of grease dripping from the grill.
- Warm to the touch: If your looking to walk around barefoot of your new deck in the summer the heat from the sun will be retained by the decking. How hot your deck actually gets will depend on what type of finish you choose.
Polyvinyl chloride (PVC) is made by combing a variety of raw materials and extruding them to create the different sizes and shapes. The specific ratio of ingredients differs between manufacturers, but they all essentially act the same.
- Durable: PVC is a non-porous product and is therefore resilient against staining. PVC will last forever; it will not rot or degrade. Most PVC decking is scratch-resistant, but it will dent if something hard is dropped on it.
- Minimal maintenance: At most all you will need to do to your PVC deck is give it a quick wash to remove any surface debris.
- Recyclable: Our supplier has a recycling program in place to keep PVC scraps and cut-offs out of landfills so they can be reused to make new products. We simply bring our scraps back to them when we are done.
- Insect proof: PVC is not a food source for insects and they will avoid it.
- Environmental impact: PVC is not biodegradable. (In fact it is used to line landfills to keep pollutants out of surrounding areas.) If a recycling program is not in place, scrap PVC can end up in a landfill. The PVC manufacturing process is energy intensive and produces significant amounts of pollution.
- Movement with temperature: Depending on the manufacturer, some PVC products can shrink and swell significantly as the temperature changes. This can cause uneven gaps at the edges of each board and, if not properly installed, could cause more significant problems.
- Hot to touch in the warm months: PVC decking can retain a lot of heat in the warm months, which can be uncomfortable for bare feet.
- Limited colors and patterns: The color choices available are mostly variations of either brown or grey. While some of the embossed “grain” patterns are very disappointing, there are a few that are either believable or at least not distracting. The patterns can be fairly repetitive and if the decking is not installed without care, you can end up with boards that look identical next to each other.
Composite decking is made from a mixture of organic cellulose (a byproduct of other wood manufacturing processes) and other non-organic materials (plastics). Like PVC, the ingredients are mixed together and extruded into deck boards. Composite decking has come a long way in the last five years or so, and many of the problems that initially haunted it, such as cracking and swelling around the fasteners, have since been resolved.
- Environmental impact: Since the wood fibers are byproducts from other wood production, and the plastics are generally made from recycled materials, composites can have significantly less environmental impact than solid PVC products.
- Cool to the touch: Composite decking does not retain as much heat as PVC and is more comfortable underfoot in the summer.
- Minimal movement with temperature: Composite decking is less prone to movement due to temperature and humidity than PVC and solid wood.
- Low maintenance: The care and maintenance of a composite deck is simple; occasional washing is all it should need.
- Insect resistant: Because it contains plastic, composite decking is highly insect resistant.
- Prone to staining: While composite decking is fairly easy to maintain, because of its porous nature it is susceptible to staining. Spilled foods and other things that are left on the deck will cause permanent stains.
- Mold and mildew growth: Manufactures are now putting additives into the products which are supposed to inhibit growth of mold and mildew but we find older decks or new decks that have been roughed up do show signs of growth The material can collect and hold moisture, which can promote mold and mildew growth and in some case cause the boards to swell.
- Fading: Ultraviolet (UV) light can cause the deck boards to fade over time.
Cap-stock decking is a fairly new material that has a composite core with a PVC shell. It has the surface durability of standard PVC without using as much PVC as a solid material.
- Increased durability: Cap-stock’s PVC shell resists stains and scratches.
- Low maintenance: As easy to maintain as PVC.
- Insect resistant: Both PVC and composite decking are insect resistant, so combining them together does not change this.
- Holds heat: Because of the PVC shell, material can still hold heat in the warm months, but still less heat than solid PVC.
- Product failure: Because the shell is made up of different materials than the core, it is possible, however unlikely, that they will shrink and swell at different rates. This can cause cracking or splitting of the boards and funny looking ends where the core is either shorter or longer then the surrounding PVC. The technology has greatly improved in recent years and manufacturers insist they have fixed this issue.
- Mold & Mildew: As with the 100% composite decking described above, there is still organic material in the cap-stock product and there is still a chance of issues arising due to moisture reacting with the organic materials, especially if the surface of the product has been compromised or the end cuts are ragged or split. Mold and mildew need to be dealt with.
Modified Natural Wood
There are two ways to modify a species of wood that can’t normally be used as a outdoor product. One way is heat treatment, like PureWood. The wood is heated at a specific rate to just below the temperature at which it burns. This process alters the structure of the wood enough to make it usable outdoors. It reduces the strength of the wood, but not enough to make it unusable as a decking product.
PerennialWood has come up with a different way to modify the wood structure. They introduce a chemical compound into the wood as it is heated under pressure. This process expands the wood’s cellular structure and hardens it, which prevents swelling and cracking.
- Resilient against insects and decay: After treatment the wood is no longer attractive to insects and resists rot.
- Reduced movement: After treatment the wood is more stable and is less affected by the natural enemies of wood, heat and humidity.
- Creates a harder and more durable surface: The decking is much less prone to dings and scratches. This is a big advantage over soft wood like cedar.
- Environmental impact: Because the wood can be sourced responsibly, there is less of an impact with these processes than PVC or non FC lumber. The chemical compound used by PerennialWood is non-toxic, which is a big plus over the heavy metals used in the traditional pressure treated process which use copper and arsenic.
- Limited colors: Until the popularity of these products increase there are only four to five color choices available.
- Limited number of species: [PerennialWood only] While the heat modification process can be used on a variety of species, currently the chemical modification only works with southern yellow pine (SYP).
- Lower strength of wood: [PureWood only] The heat treatment process reduces the “ultimate stress,” or strength, of the wood. This is not as much a factor for decking products, but should not be overlooked.
- New Process: Both of these processes are relatively new and have not been scrutinized by the building industry.
Nailing and Screwing Methods
Once you have chosen your deck material there are a variety of both hidden and visible fastening methods, which we will go over with you to help you decide which is best for your needs. We will address both what’s most visually appealing and what fastener works best with what decking product.
To give you an idea of what the products cost in relationship to each other I’ve listed some prices below. Actual price will vary depending on color and manufacturer.
(based on 5/4”x 6”decking per square foot)
- 100% composite $6.54
- 100% PVC $6.86 * imprinted wood grain
- Cap stock $ 7.25
- Modified wood $7.41
- Mahogany (wood) $7.43
- 100% PVC $8.25 * multicolored textured and wood grain…better visual quality
Summing It All Up
Clearly you have a lot of options when it comes to decking. Even after you choose a material, there are more decisions to make with specific brands of decking, fasteners, and railing systems. But don’t worry. We know these decisions can be tough. We’re always happy to help you find the products that best suit you and your family and get you on your way to a beautiful new (or restored) outdoor space. We love building decks, and our clients love living on them!