Deck Design Guidelines & FAQS

Plastic Lumber FAQS

1) Composition
Our plastic lumber is a solid, non-hollow foamed recycled product made from Recycled High Density Polyethylene ( ReHDPE ) plastic. Common HDPE ( recycling code # 2 ) products are gallon style milk, water and juice containers, as well as some detergent and shampoo bottles. Our plastic lumber is 100% plastic with no wood fillers to rot, peel, weather or blister, and generally contains over 90% recycled HDPE plastic material.

2) Color
Our plastic lumber utilizes Ultra-Violet (UV) stabilized colorants added during the manufacturing process to ensure a long lasting, fade resistant product requiring no staining, painting or sealing of any kind. Even when cut, the exposed product is colored. Standard deck colors are: White, Ivory, Oak, Dove Gray, Dark Gray, Black, Teak, Weathered Teak, Redwood and Hunter Green.

We also have special order colors available subject to an additional charge.

3) Texture
Our plastic lumber is manufactured with a slight wood grain-like texture, creating an easy to clean surface that is no more slippery when wet than a painted or sealed wood deck. A natural film, which can’t be seen or felt, is left on the surface of the material after manufacturing. Sunlight will normally burn off this film in a few weeks. A rougher, slip resistant ( knurled ) finish is available if required and lead time may be a factor. Keep in mind that the coarser the surface finish, the more likely dirt will tend to collect on it.

4) Product Life
Our plastic lumber is still going strong after over 20 years of accelerated weather testing. We haven’t seen the total life span of the product to date. We do have product installed on boat docks since 1976 with no sign of degradation.

5) Maintenance
Our plastic lumber is virtually maintenance free! No staining, painting or sealing is ever required! Washing with a garden hose or mop is about all that is needed under normal circumstances. For stubborn stains, a mixture of bleach and water (1 part bleach to 10 parts water) can be used without harming the product. After all, bleach and acids are normally sold in HDPE plastic bottles.

6) Tools
Standard woodworking tools can be used. You may have to use a lower speed with your router or planer/jointer to prevent gumming up of the router bit or the planer/jointer knives. Carbide tipped bits and blades are recommended. Always use tools according to manufacturer’s instructions, and wear protective clothing and safety glasses for your safety.

7) Weight
The weight of this product is comparable to Oak lumber.

Sizes and Shapes available for decking:

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Flooring: Standard = 3/4″ x 6 1/2 T&G or 3/4″ x 5 1/2″ flat (typical 1x 6)
Special-Order: 3/4″ x 3 1/2″ Flat or T&G (typical 1×4), 1 x 5 1/2″ (typical 5/4) or 1 1/2″ x 5 1/2″ Flat or T&G (typical 2×6)
Railing: Standard = 1 1/2″ x 3 1/2″ flat (typical 2×4) or 1 1/2″ x 3 1/2″ Deluxe Handrail
Spindles: Standard = 1 1/2″ x 1 1/2″ (typical 2×2)
Special Order: 1 1/2″ Round or Full 2 x 2
Posts: Standard = 3 1/2″ x 3 1/2″ (typical 4×4)
Fascia / Skirting: Standard = 3/8 x 6 T&G or 1/2″ x 8 or 5/8 x 12
Other: View our profile listing on our web site for other sizes and profiles available.
Railing: Standard = 1 1/2″ x 3 1/2″ flat (typical 2×4) or 1 1/2″ x 3 1/2″
Deluxe Handrail Spindles: Standard = 1 1/2″ x 1 1/2″ (typical 2×2)
Special Order: 1 1/2″ Round or Full 2 x 2
Posts: Standard = 3 1/2″ x 3 1/2″ (typical 4×4)
Fascia / Skirting: Standard = 3/8 x 6 T&G or 1/2″ x 8 or 5/8 x 12

Plastic Lumber Deck Guidelines

1) Board Length
Our plastic lumber will expand and contract along its length, similar to vinyl siding, with temperature changes (see Expansion / Contraction chart below). It is recommended that the deck boards should not exceed 16 in length. Apply deck boards across the shortest length of the deck whenever possible. Use of multiple deck levels to create transitional zones, or use of board patterns such as herringbone, checkerboard, angles, change of direction, etc. can all be used to increase the overall deck size while maintaining a minimum length on the deck boards.

Working with deck sections larger than 16
Installation of lengths longer than 16 should be avoided due to the expansion and contraction of recycled plastic decking. This can be accomplished by using any of the following techniques.

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Option 1 (for decking surface):
Use feature boards to break up the deck into manageable sections of
shorter lengths. The structure must be modified to support the feature board while also supporting the ends of the deck boards running up to it.

To do this, a wood 6×6 is installed directly below the feature board and two joists are installed on either side of the 6×6. These are all joined together using bolts with nuts and washers (see end-view illustration).

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Option 2 (for decking surface):
Use T-Strip / Joint Covers to break deck up into manageable sections of shorter lengths. The structure must be modified to support the T-Strip while also supporting the ends of the deck boards running under it. To do this, a joist is installed directly below the feature board with a joist installed on either side of it. These are all joined together using bolts with nuts and washers (see end-view illustration). The decking boards can be installed first leaving an adequate gap between then to allow for the installation of the T-Strip.

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Option 3 (for decking surface):
The layout of the deck can be designed in a way to break a very large (i.e. 24″ x 24″) deck into quadrants of alternating board directions (see top-view illustration).

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Option 4 (for decking surface):
To avoid having to run joists in the long direction, over-length decks can be installed using wood 2×4 sleepers laying flat on 12″ centers across 2x joists on 16″ centers. This allows the frame of the deck to be installed as usual while working with the shortest length of the deck.

2) Joints
Avoid butt joints whenever possible. If unavoidable, use either installation option 1 or 2 as illustrated Here.

3) Railing
Railing should not exceed 48″ between posts on all-plastic rails The bottom rail, when used, should be supported in the center to prevent sag.

Deluxe Rail with stainless steel channel should be used on rail sections that are 48″ to 72″ wide.Rail sections should be designed with spindles flush with each end of the rail with spindles evenly spaced between making sure distance between spindles conforms with local building codes. Rails sections are then mounted between the posts by screwing through the outside spindles into the posts.

DO NOT toe nail rails into the posts. Screws will simply pull out when rails contract in cold temperatures.

4) Substructure
Our Premium Grade plastic lumber is not suited for structural purposes. We recommend using a high quality kiln dried treated wood product, or galvanized steel, for your substructure to prevent warping and bowing. We also offer Structural Grade Plastic Lumber. Wind bracing should be installed on a 45 degree angle to the joists, at 4 to 6 intervals, especially on larger decks. Traditional blocking methods may also be used.

The top surface of the joists must be flat to avoid the flooring taking on any peaks or valleys of the joists. Be sure all bowed joists are installed with the bow up if they must be used. Badly bowed joists should not be used. The joist system should be properly square.

ACTUAL LUMBER SIZE ( inches ) MAXIMUM AVAILABLE SPANFOR 40 psf ( inches )
3/4 x 5 12″
3/4 x 6 T&G 12″
1″ x 5 16″
1 x 3 16″
1 x 5 23″

5) Fascia / Skirting
All exposed wood joists, and optionally the area between your deck and the ground, should be covered to complete the deck. 3/8 x 6 T&G, 1/2″ x 8 or 5/8 x 12 Plastic boards are designed for this application. It is recommended that these boards be installed vertically or diagonally due to the effect of expansion and contraction. Horizontal installation is acceptable with the use of expansion gaps and caps covering the expansion areas. Contact Plastic Lumber Yard for more details.

Wrapping Wood Posts
Wood support posts can be wrapped with plastic lumber materials. This will enhance the overall look of your deck as well as further reduce the maintenance your deck will require.Use either 1/2″ or 5/8 thick materials wide enough to be ripped down to the widths necessary to cover the post. Be sure to only fasten plastic to plastic and to leave a gap at the bottom to allow for movement. This gap can be covered with cutoff trim pieces. DO NOT fasten the material to the post (See end-view illustration), except at one point at  the top to hold it in place. This will allow the expansion and contraction of the material.

Installation:

1) Posts
Posts should be mounted before installation of the flooring. The posts should be thru-bolted to the joists using a minimum of two 1/2″ carriage bolts with the nuts to the inside of the deck. This will allow the bolt heads to be easily covered later with a fascia board if bolted through the rim joist.

NOTE: Be sure the rim joist is securely braced wherever a railing post is to be fastened to prevent movement of the post in the finished railing assembly.

2) Board clearances
Ideally, plastic boards should be installed at the midrange of normal temperatures for the area at the time of installation (i.e.: approx. 60F in northern climates).

A space must be left next to building walls and around posts to allow for expansion and contraction of the plastic lumber. Generally, a 3/8 gap is sufficient, depending on the temperature of the boards at the time of installation and the length of boards being installed. Please refer to the expansion / contraction chart below to verify this. A trim board can be used, if desired, to cover the gap. Pre-cut post base trim pieces are available.

NOTE: When cutting notches into plastic lumber, drill or router a rounded corner in the cut out to prevent cracking at the corner, as you would with any other hard surface material. This can be accomplished by drilling a 1/2″ hole at the corners of the notch and then cutting up to the drilled holes.

3) Board Edge Overhang
A 1 finished overhang of the deck boards beyond the rim joist is recommended.

NOTE: It is generally easier to allow additional overhang of every floorboard during installation, followed by trimming this overhang on a straight line when finished. A slight radius can be added to the trimmed floorboards top edge with a router to create a more aesthetically pleasing effect.

4) Fastening
3/4″ x 6 T&G floor boards Blind screw through the tongue into each joist with # 7 x 2 1/4″ self-tapping stainless steel trim head screws. This results in a very clean and neat looking deck floor with no visible fasteners.

NOTE: No pre-drilling is required with this installation method. Firmly secure decking starting nearest to the house, working away from the house, down the entire length of the board. 3/4″ x 5 1/2″ Flat floor boards. Face screwing with two # 10 x 3 self-tapping stainless steel screws into each joist is recommended. Boards should be predrilled and slightly countersunk to have the cleanest looking installation.

NOTE: If you don’t pre-drill, you may want to tap down the little mushrooms that may form when using self tapping screws. This will hide part of the screw head for aesthetic purposes.Firmly secure decking starting nearest to the house, working away from the house, down the entire length of the board.

Note: Installer and/or purchaser should consult local building codes prior to the building process.

Note: Our premium plastic lumber should be stored on a flat surface prior to installation, and boards should be carried on edge for better support.

Note: Two cuts must be taken when rip cutting plastic lumber. This is due to the difference in density between the outer skin of the board and the boards center. For example, if a 3/4″ X 5 1/2″ board needs to be ripped to 3/4″ x 4, 3/4″ should be ripped from both sides.

Information included in this guide is subject to change without notice.