Pressure Treated Lumber Decking
As stated above, pressure treated lumber is the dominate decking product in the market. Relatively low cost, excellent strength and workability characteristics, and wide availability are responsible for its popularity. Even if you select another decking material you will almost certainly still have pressure treated lumber used in your deck for all or most of the structural members. Alternative materials are either inadequate or too expensive for structural purposes.

Several waterborne preservatives are commonly used for preservation including Chromated Copper Arsenate (CCA), Alkaline Copper Quat (ACQ), Copper Azole (CA) and Sodium Borate (SBX). As of December 31, 2003 CCA has been withdrawn for most residential consumer treated lumber applications. (See: http://www.backyardamerica.com/cca.htm ). Copper is the primary fungicide in these preservatives. The preservatives are forced into the wood fibers under pressure in large chambers. Southern pine is the lumber species most commonly used for pressure treated decking and framing in the eastern part of the country because its cell structure allows adequate preservative penetration without incising the lumber.

Incising is the perforation of the lumber surface with small slits which allow the preservative to penetrate. It is required for most western softwood species. Pressure treated hem-fir is the most commonly used. Hem-fir actually refers to several western softwoods including Douglas fir, western hemlock,  red fir, silver fir, and white fir. The decking is often pre-stained for a cedar like appearance. When cut or drilled a preservative must be applied to the newly exposed surface to prevent rot.

As the popularity of redwood increased there was increasing concern that all of the redwood forest would be destroyed. That concern led to industry and government actions to preserve the remaining old growth redwood  trees. Today the vast majority of redwood comes from trees harvested from managed  forests on a sustainable basis.

You need to be careful about what you are buying when ordering redwood. There are several grades of redwood that are suitable for use on decks. They vary significantly in appearance and in cost. The grades are primarily concerned with the amount of less durable sapwood compared to the very durable heartwood and with the number and sizes of knots. Before selecting redwood as your decking you should become familiar with the names of the grades, their appearance, relative cost, and expected life of each.

A testament to the popularity of cedar decking is the number of composite and plastic decking manufacturers who have tried to duplicate the grain and color of real cedar decking. Most do not come close to the beauty and texture of the real thing.

Tropical hardwoods have become increasingly popular in recent years as they have become more available and cost competitive. Most can be finished to an almost furniture quality or left unfinished to weather to a silver gray. In this very broad category of decking people are probably most familiar with teak. Although still used for some very high-end residential and commercial decks, teak's high cost has resulted in it is used mainly for furniture and decking and trim for yachts. There are several tropical hardwoods that have many of the favorable characteristics of teak but at a lower cost.

• Ipé (E-pay) or Brazilian Walnut is also sold under brand names such as Pau Lope®  and Iron Woods®. Typically dark brown in color, it may have lighter colored sapwood striping, Ipé has a very fine texture, is very hard, very dense, and very strong. It is difficult to cut and bore, requiring more labor to install than native woods. Ipé is very durable lasting 25 years or more (The Pau Lope® warranty is 40 years!) This decking only requires sealing to maintain its beautiful rich color. Without a sealer it will weather to a silver gray with virtually no splintering. Imported primarily from Brazil and Central America.
• Massaranduba or Brazilian Redwood is similar to Ipé in appearance (although redder in color) and physical characteristics it is often lower cost but not as widely available. Imported primarily from Brazil and Central America.
• Cumaru or Brazilian Teak is also similar to Ipé in physical characteristics - very hard, very strong, and very dense. The color is often described as an orangish brown. Cumaru naturally weathers to a beautiful, silvery-gray patina. Imported from South America.
• Mahogany. There are many different species and sub-species of mahogany. Colors can range from white and yellow to light and dark red. The lauan genus (Shorea) contains about 70 species that are commonly called Philippine Mahogany. These woods are typically sold based on color and density rather than by species. Meranti, a plantation grown Philippine mahogany, is a common variety that has its own faults and a wide range of decay resistance. It must be maintained with water repellant to protect it and keep its dimensional stability.  Philippine mahogany is not as durable or dimensionally stable as real American mahogany, which comes from the West Indies, Mexico, and Central and South America. American mahogany has a beautiful, dark red appearance that will last for decades. Obviously when buying mahogany, research the wood and be sure to ask for the species name and the physical characteristics of the wood you are buying.
   

  Advantages High WOW factor - beautiful when properly finished. Naturally rot and decay resistant with a useful life of 25 years or more. Excellent dimensional stability Available in 1" and 5/4" decking Wide selection of visible and hidden fasteners are available. Extremely strong and hard. Very resistant to scratches and dents. Virtually splinter free.

  Disadvantages Weathers to a silver gray without periodic cleaning and application of stain/sealer. Relatively expensive, comparable to clear grades of redwood and cedar. Oily surface makes staining and painting difficult (but why would you?) Difficult to work, hard on tools and extra labor is required for installation. Not widely available.

  Comments: Above comments do not apply to Lauan or Philippine mahogany which is less durable and structurally inferior. Be very careful when selecting and specifying the lumber grade to be used. Imported woods are not regulated as much as domestic lumber. Often this lumber is sold by brand name. Stainless steel fasteners are less likely to stain the decking. Do not use electro-galvanized fasteners on the decking. Most will require pre-drilling before the decking can be screwed in place. Consider trim head stainless steel screws for minimum appearance and high holding strength as a lower cost alternative to hidden fasteners. Be careful to follow the distributors requirements for spacing and fasteners. Most are dry products , but not always. Use treated lumber for framing to save on cost.

COMPOSITE DECKING
There is a lot of confusion when it comes to composite decking. Some people think all composite decking is Trex (due in large part by a great marketing effort by the Trex Company to introduce composite decking to the market.) In fact, there are over 80 composite decking products currently being offered.  By definition a composite is a material, in which two or more distinct, structurally complementary substances are combined  to produce a product with structural or functional properties not present in any individual component. In the case of composite decking the primary components are most often a plastic and an organic material, usually wood fiber. But not all composites contain wood fiber and new products with new combinations of materials are rapidly appearing on the market. Some things to consider when choosing a composite decking:

• Type of Plastic. The most commonly used plastic in composite decking is polyethylene. High Density Polyethylene (HDPE) is used for things like milk jugs and other similar containers. Low Density Polyethylene (LDPE) is used for bags and wrappers. Both are recycled in huge quantities with decking being a major use of the reclaimed material. Denser, lighter, and stronger, high density polypropylene (HDPP)  is used for portable gas cans, Tupperware, and furniture. Because of its longer life, HDPP is recycled in smaller quantities. Decking made with HDPP is more likely to be all or mostly virgin material. Recently some manufacturers have introduced composite decking using Polyvinylchloride (PVC) as the plastic. PVC is discussed in more detail below.
  
  Which is best? It depends. Polyethylene based decking is more common so your selection is greater. There are more colors, profiles, and textures available. It also tends to be less expensive because of the recycled content. Polypropylene based decking is typically stronger, allowing for greater spans between joists. It will also wear better than polyethylene based decking.
• Profile. Composite decking is available in solid and hollow or ribbed profiles. The solid is easier to work in finishing the edges using a saw or router. The hollow/ribbed is lighter, but must be used with special trims and end caps. Some composites are available in a tongue and groove (T&G) profile which is particularly useful for screened porches.
• Reinforcement. By a huge margin, wood flour is the most common reinforcement fiber used in composite decking. It is readily available as scrap and saw dust from all types of wood product producers. The material is typically ground into a powder before being combined with the plastic. This mixture, along with additives for color and other properties, is blended, heated, and extruded in continuous ribbons of decking. Other materials such as rice hulls are used, but wood is most common.
  The wood fiber is surrounded by the plastic to protect it from moisture. Earlier designs would sometimes have problems  with the wood becoming exposed after the surface has been worn down. This typically results in mold or mildew problems. Newer products seem to have this problem solved - time will tell.
• Fastening System. The first composites (Trex) were nailed or screwed to the framing. The material was so stable some contractors even used finishing nails to fasten the decking - a practice that is not recommended by any manufacturer. Today there are many ways to attach the decking. In addition to nails and screws, a variety of hidden fastener systems are available. Hidden fasteners give a cleaner look and eliminate worries over stains from nails or screws. It is very important to understand the manufacturer's recommendations. Some decking cannot be nailed. Others must be pre-drilled before being screwed to the joist.
• Warranties. Warranty time limits vary from 10 years to "lifetime". Some are transferable if the building is sold. Labor for replacement may be included. In other words there's a lot of variations and it pays to read the fine print to understand the rights that you will have if something goes wrong.
• Color and Texture. When first introduced Trex followed the Henry Ford example and offered any color and texture as long as it was smooth and gray. In time additional colors were added and the most recent models have a wood grain texture and tropical wood tones. Until recently, many people thought that composite decking looked too fake. That is changing as companies have developed more realistic colors and textures. With 80 plus composite decking products you should be able to find a color and texture that meets your expectations.

The table below details these features for some of the most popular and widely available composite decking products.

VINYL DECKING
There has been a surge in interest in vinyl decking recently and there are many improved products on the market. Vinyl decking has two primary profiles and formulations available: hollow and solid.

Hollow PVC Decking
The walls of the hollow PVC decking are normally just a fraction of an inch thick. Many profiles have been designed to achieve the strength and stiffness required to be a acceptable decking surface. Unlike the composite decking discussed above which contain 10% to more than 60% wood or other organic material, vinyl decking has no wood filler. Instead it may be a compound of two or more formulations of polyvinylchloride (PVC) and have additives such as glass or carbon fibers. Most PVC outdoor products, including decking, are now co-extruded with two layers of PVC. The outer layer, or capstock, contains a UV inhibitor, typically titanium dioxide, and other additives that affect the appearance and impact resistance. The inner layer is typically thicker and may contain additives to increase strength and stiffness. There are many variations in formulations and profiles.

Vinyl decking has improved in many ways over in recent years. There are now more color choices and there are several surface textures available. This decking is typically fastened with screws often with a hidden fastener configuration. Most of the newer designs are easier and faster to install than wood or composite decking. Also there are specialty decking models as well that have unique features. We offer an interlocking vinyl decking that is watertight when installed according to the manufacturer's instructions. Another popular variation is vinyl over-decking. This product is about 1/2" thick and be applied over split and discolored decking to renew an otherwise structurally sound  but ugly deck.