Design Considerations

Section Contents:

Product Characteristics
Technical Data
Installation
Cost
Maintenance Requirements

 

Product characteristics. Vinyl fencing, decking and railing have come a long way since the days on horse farms. Architects, general contractors, remodelers and landscape architects can now offer their clients products that have exceptional weatherability and durability along with minimal maintenance.

Quality vinyl outdoor living products are designed to remain consistent in shape and tend not to warp or swell. There are no fibers in the product, so there are no burrs, splinters, chips or slivers. Because of added stabilizers and UV inhibitors, the products are weather-resistant and waterproof.

All outdoor products will fade over time. Vinyl outdoor living products are no exception. The advantage that vinyl has over other materials is that it fades uniformly. (See "Technical Data.")

Vinyl won't blister, rot, rust or peel and it weathers uniformly. Because color is extruded throughout the product, it doesn't need paint or other surface treatments such as water sealants and stains. The way it is designed and engineered to be put together, no surface screws, nails or sharp edges show. It is also resistant to stains. Testing for chemical resistivity reveals that vinyl is not affected by rock salt or other chemicals used for snow removal.

Vinyl decks offer slip-resistant surfaces and since vinyl does not splinter or have rough edges, it is a safe material ideally suited for decks. That is also why it is so heavily used in the equestrian sector; direct impact into a rail doesn't cause splintering and minimizes injury to a horse. Vinyl horse fencing systems can be designed to bend back into place. In the case of a concentrated load impact, vinyl horse fencing can simply pop out of a post and quickly be refastened. For example, at the Westwind Arabian Training Center in Westfield, Ind., it was documented that a young stallion ran against some vinyl rails and the fence "popped" the horse back into the pasture.

Under normal use, vinyl fencing will not break when installed properly. If subjected to a direct substantial impact (e.g., an automobile running into a fence line) vinyl fencing can break. Planks, pickets and rails are easily replaced if damaged.

Vinyl outdoor living products stand up to typical North American temperature extremes; although vinyl will become less flexible in colder weather conditions (sustained temperature below 20 F). Nevertheless vinyl will not break or crack unless subjected to an unusually strong impact. Also, it is normal for vinyl materials to expand and contract during temperature changes. Proper design and installation can accommodate this process.

Another product characteristic of vinyl is that minor scratches don't show or lead to bigger problems. With metal, scratches can expose a product to the elements, allowing rust to set in. Likewise, scratches on wood can expose it to accelerated degradation, more swelling and harmful insect infestations.

Typical color choices for vinyl fencing and decking are white, tan or gray. However, new color choices will soon expand the selection. For example, two of the newest colors for vinyl decking are wood tones similar to redwood and pressure-treated wood. Vinyl railing comes in a variety of colors and can be matched to a designer's choice.

Dark colors are not recommended for vinyl planking because they have high heat buildup that could cause unreinforced planks to distort, sag or bend.

Some manufacturers offer lifetime warranties that are transferable with the sale of property. Extended warranties typically last more than 25 years.

Technical data. The performance of vinyl outdoor living products is measured by a variety of physical characteristics. Following is a brief description of each product's standards and testing criteria.

Decking: Vinyl decking is subjected to tests for low temperature, high temperature, puncture loads, blunt impact, uniform loads defined by uplift and live loads, fire resistance, weatherability and stair tread structural integrity.

•Low temperature test - A vinyl plank system is subjected to test loads of 250 pounds at a low temperature of -20 F for not less than four hours.


•High temperature test - A vinyl plank system is subjected to test loads of 250 pounds at a high temperature of 120 F for not less than four hours.


•Puncture Loads - A vinyl plank system is subjected to 200-pound concentrated loads at low and high temperature extremes as described above.


•Blunt Impact - A vinyl plank system should be able to withstand an impact force of 36 pounds at the defined low and high temperature extremes. There should be no visible shattering or cracking of the walking surface area, or disengagement from the substructure or other plank system components.


•Uniform Uplift - There should be no disengagement of the plank system from the joist system or other plank system components when exposed to a 75 pounds per square foot (psf) uniform structural load applied to the underside of the assembly.


•Uniform Live Load - There should be no disengagement of the plank system from the joist system or other plank system components when exposed to 100 psf uniform load to the walking surface side of the assembly.
For more information, see the Draft Voluntary Specification for Performance of Exterior Walking Surface Plank Systems, available through the American Architectural Manufacturers Association (AAMA) (see "Resources").

Fencing: The specifications for fencing differ depending on the type or use of the fence - whether it is for commercial, residential or agricultural use - but all fence profiles conform to the American Society for Testing and Materials (ASTM) standard ASTM F964: Standard Specification for Rigid Poly(Vinyl Chloride) (PVC) Exterior Profiles Used for Fencing. See "Bibliography" for a listing of other applicable ASTM standards.

It is best to check with individual manufacturers on the specific standards that apply to a particular type of vinyl fence. Standard testing for vinyl fencing includes tests that measure its ability to withstand cracking, temperature extremes, direct impact, warping and discoloration.

•Length, Height and Width - The nominal length, height and width of vinyl fencing profiles should be as agreed upon between the purchaser and the seller. The actual length should be within 1/4" of the nominal length and the actual height and width should be within 1/16" of the nominal height and width.


•Flattening - There should be no evidence of splitting, cracking or breaking when fence profiles are tested. Testing involves placing three planks in a suitable press between parallel plats. A uniform load is then applied at a rate that compression occurs within two to five minutes. On removal, the planks are examined for splitting, cracking or breaking. A split or crack of 1/33" constitutes a failure in the test.


•Impact Resistance - Vinyl fence profiles should be tested for impact resistance in both cold and hot temperature extremes.


•Warping - Warping tests are performed on all sides of a fencing profile. Measurements against a straightedge to the nearest 1/16" are conducted.


•Weatherability - Vinyl fence profiles should maintain a uniform color and be free of any visual surface or structural changes such as peeling, chipping, cracking, flaking and pitting for a period of time consistent with the manufacturer's warranty.


•Color - The color of the fencing profiles should be as agreed upon between the purchaser and the seller. The color specified should be uniform throughout the product.
The standard also dictates that the fence be free from visible cracks, holes, foreign inclusions, or other defects. The fencing profiles should be as uniform as commercially practicable in color, opacity, density and other physical properties.

Railing: While the provisions of codes and standards differ slightly, most handrails must be designed and constructed to withstand a concentrated load of 200 pounds applied at any point and any direction. Intermediate rails, balusters and panel fillers are designed to withstand a horizontally applied load of 50 pounds on a one-square-foot area. The top of a guardrail must be at least 36" from the floor. The spacing in the guardrail ornamental pattern, balustrade or pickets must not allow the passage of a 4" diameter sphere. Railing systems, regardless of material composition are identified in three categories: Decorative Grade (for installation less than 30" off the ground); Residential Grade (for installation more than 30" off the ground); and Commercial Grade (a railing height equal to or greater than 42" high).

•Concentrated Load - All handrail assemblies and guardrail systems should be able to resist a single concentrated load of 200 pounds applied in any direction at any point along the top and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building.


•Distributed Loads - Handrail assemblies and guardrail systems for commercial applications should be designed to resist a load of 50 pounds per foot (pound force per linear foot) applied in any direction at the top. To transfer this load through the supports to the structure for one- and two-family dwellings, the minimum load should be 20 pounds per foot.


•Baluster/Picket Load - Intermediate rails should be designed to withstand a horizontally applied normal load of 50 pounds on an area not to exceed one square foot including openings and space between rails.


•Concentrated Post Load - The railing should be designed to withstand a concentrated load of 200 pounds applied horizontally at the top of the post.


•Concentrated Handrail Bar Load Test - The handrail bar should be designed to resist a single concentrated load of 250 pounds applied in any direction at any point. The test should be performed with the handrail bar installed as recommended by the manufacturer.
For all vinyl outdoor living products, weatherability testing is also conducted to measure resistance to the elements including sun, wind, rain and pollution. In addition to accelerated tests conducted in a laboratory, outdoor exposure tests are done in "real time." There are three standard test climates representing the extremes encountered in the continental United States:

•Arizona - Hot and dry, average 300 days of sun per year.


•Florida - Hot and moist with exposure to salty air.


•Ohio - Temperature extremes, from fairly hot and moist in summer to below zero and moist in winter. Testing in this area also allows manufacturers to measure product performance in industrial zones.
Test results reveal that outdoor vinyl products retain a high degree of their original physical properties and color during exposure to these various weathering conditions. Test results are available through individual manufacturers (see "Resources").

In a region such as Arizona, color loss is minimal and generally occurs within the first 12 months of exposure. Color test results for white, tan and gray over a 12-month period showed a Delta E (DE) - which measures total color change loss - of 1.6. Considering that the naked eye cannot detect a change in DE of less than 2.0, this is a negligible amount of color change. Test results are available through individual manufacturers (see "Resources").

Vinyl has a relatively high ignition temperature as compared to other materials. This means that even when exposed to an open flame source, vinyl will resist ignition much longer than most materials, which could serve to slow or even stop the spread of fire.

Installation. Techniques for installing a vinyl fence are similar to those of a wood fence. The same tools and principles apply with the notable exception that vinyl fencing does not require job-site welding and gluing. As with wood, vinyl posts are set in the ground with gravel and concrete. The posthole depth should be below the frost line to avoid the effects of ground shifting and swelling. Two types of fastener systems are commonly used to fasten rails to posts:

•Fence rails attached to posts by galvanized screws hidden in the post so that no screws show, or


•A vinyl or nylon snap-in type system that uses clips to secure rails to posts.
Vinyl deck systems are installed by a number of different methods based on specific designs of the manufacturer. Vinyl deck planks are installed on 16" or 24" centers, depending on design. There is a two-piece installation system that requires long clip strips to be attached to standard wooden deck joists - the supporting structure located beneath the vinyl plank system - by using galvanized screws. Spacing of the strips is based on the width of the vinyl planks to be installed. Then the planks are laid down and secured by snapping into place (typically by using a rubber mallet). Two-piece systems come in either a base profile (plank) with a decorative cap added, or a full profile (plank). Another type of installation is with a one-piece system where the planks directly fasten to the substructure by screws or clips. Vinyl decks are typically installed on a standard wood substructure, but wood members can be clad with vinyl to provide a more finished appearance to the installation. Vinyl deck planks can be cut just like wood deck planks using a power saw. A blade made for vinyl will deliver the smoothest, cleanest cuts. If that type of blade cannot be found, a fine-toothed tungsten carbide blade may be used.

The same tools that are used for wood materials are also used for vinyl fencing, decking and railing. They include:
•electric drill


•post hole digger


•sawhorses


•tape measure


•jigsaw


•hand or power saw


•c-clamp or vice grips


•dead blow hammer (preferred) or rubber mallet


•level


•screwdrivers


•concrete mix


•sledgehammer


•square
Vinyl railing is installed in a similar way to vinyl fencing, with the main difference being the post mount. The first thing that is done when installing a vinyl rail is the attachment of a post mount. The galvanized steel post mount is bolted to both the rim joist and the floor joist. Vinyl posts are then installed by simply sliding over the post mount. Most railing styles feature a bottom horizontal rail; if so, then this is installed next, followed by the pickets and then the top horizontal rail. For railing at ground level and up to 30" above ground reinforcement is used in the bottom rail only. For those railing systems above 30" off the ground, both the top and bottom rails may require reinforcement to be inserted. The bottom rail is installed by sliding it into pre-cut holes. It is centered and secured in place with non-corrosive screws, clips or locking mechanism. Next, vertical pickets are placed into pre-cut holes in the bottom railing. Then the top railing fits over the pickets and is secured into place the same way as the bottom railing. There are several options for post caps to add a finishing touch such as a dome-type cap, gothic style or a New England style cap.

Cost. According to Today's Homeowner, vinyl decking ranges from $7 to $12 per square foot (not installed), which is 30 to 50 percent more than a standard pressure-treated wood deck. In addition, the magazine Workbench reported that vinyl decking could cost twice as much as pressure-treated southern pine, which is the least expensive wood on the market. However, the difference in cost goes down when compared to more expensive woods such as tropical hardwood, redwood and cedar.

Typical costs of vinyl fencing range widely because of its versatility, which allows it to be configured in various styles of functional and decorative fences. Vinyl fences range in price on an installed basis from $6 per foot for a typical ranch rail to more than $40 per foot for custom ornamental fences.

Vinyl railing systems are cost competitive with painted wood railing systems at an installed cost from the high teens per foot up to the upper 20s for basic designs. While the very lightweight metal railing systems can be less expensive than vinyl railings, specialty vinyl railings averaging $50 to $100 per foot are extremely competitive with welded commercial aluminum railing systems.

Despite these higher initial costs, vinyl's lifetime of low maintenance and long-term durability makes it extremely competitive, especially when compared to the lifecycle maintenance costs of other products. When purchasing products made with other materials, there is the initial cost of the product itself and, in cases where painting is desired, the added cost of labor and materials. After that are the costs of repairing and replacing worn boards, adding chemical preservatives, repainting or re-staining and the labor cost associated with maintenance. This can dramatically increase the lifecycle costs of wood and/or metal fencing, decking and railing.

According to one industry analysis, the average cost to maintain a standard wood deck is approximately 76 cents per square foot annually. For a 10' x 20' wood deck, the average annual maintenance cost is $152. A standard southern yellow pine deck will need to be completely replaced every 7 to 10 years, depending on how well the deck has been maintained. Vinyl decks, on the other hand, require virtually no maintenance and will last more than 20 years.

To illustrate the impact of lifecycle cost in fencing materials, the owners of two horse farms in Kentucky kept stringent documentation on maintenance and labor costs on their standard wood horse fences for a period of three years. Periodically the fencing was painted according to installer's recommendations and worn boards were replaced as needed. The records revealed an annual maintenance cost of 50 cents to 70 cents per linear foot. Therefore, maintenance on a 5000-foot horse fence could cost between $2,500 and $3,500 annually. Using this example, the savings on maintenance alone can pay for the difference in original cost of a vinyl fence in seven years or less.

Maintenance requirements. Ease of maintenance is vinyl's most significant advantage over other materials. As with all exterior products, vinyl outdoor living products will become dirty when exposed to the elements. A mild detergent and water should be sufficient to keep the products looking new. For tough stains, a soft abrasive scrub or baking soda works well. Light chalking may appear on the surface of some outdoor vinyl products. This would also be normal on any coated or painted surface. Washed away by rainfall and normal changes in weather, this process helps to keep the product looking like new. There is no need to paint any outdoor vinyl product because the color pigments are added at the beginning of the manufacturing process and are compounded into the raw material prior to production. Although not classified as graffiti proof, most paint can be removed from vinyl outdoor living products with just a little effort. It may require the use of a pressure washer or in an extreme case the use of paint thinner. Four-hundred-grit sandpaper can be used when some spots will not come off using the above methods.

As with other materials such as wood and wood products, direct contact with lawn and garden equipment can cause damage to the posts. Use caution when operating any type of equipment near vinyl posts, especially commercial trimmers.

Vinyl outdoor living products will, when subjected to extended damp weather, collect mold and mildew. They are, however, easily cleaned with a solution of mild household detergent and water.

The phenomenon of tribo-charging - the buildup of static electricity on a flat surface - can affect vinyl walking surfaces. This phenomenon occurs most frequently in dry climates, where hot, dry winds and dust-born particles can create static electricity on the surface of vinyl decks. This static electricity is the same as when people drag their feet across a rug on a dry day or rub a balloon on fur or wool. Some manufacturers are now incorporating anti-static additives to their products to prevent this problem; a quick hosing-down of the deck with water will also dissipate the static electricity.