Planning a Diagonal TimberTech Decking Layout

Visual Impact and Design Considerations

The primary reason homeowners and designers opt for a diagonal decking layout is its distinct visual appeal. A diagonal pattern can break up the monotony of a large rectangular deck or add an interesting focal point to a smaller area. It can also create an illusion of depth and width, making a narrow space appear larger.

Consider how the diagonal lines will interact with adjacent structures, such as the house, railings, or landscaping. A 45-degree angle is common, but slight variations can also be explored for unique effects. For example, a diagonal pattern can visually connect different zones of a multi-level deck or lead the eye towards a specific feature like a fire pit or outdoor kitchen.

Material Calculation and Cut Waste for Diagonal Layouts

One of the most significant differences when planning a diagonal layout compared to a straight one is the increase in material required due to cut waste. When boards are laid diagonally, the ends of each board must be cut at an angle, typically 45 degrees, to fit the perimeter of the deck. These angled cuts generate more unusable offcuts than straight cuts.

As a general rule, expect to add an extra 15-20% to your total board quantity compared to a straight layout for a diagonal pattern. This accounts for the triangular waste pieces at the edges and any miscuts. Longer boards, such as the 16-foot or 20-foot TimberTech lengths, can help minimize waste by allowing more continuous runs, but careful planning of cuts is still essential. The 12-foot, 16-foot, and 20-foot lengths are available for TimberTech boards.

For a simple rectangular deck, a rough estimate for diagonal coverage can be obtained by multiplying the deck's square footage by 1.15 to 1.20 (for 15-20% waste). This gives you an adjusted square footage to divide by the coverage per board. However, for complex shapes or decks with many angles, a detailed cut plan is recommended to optimize material use and accurately estimate quantities. It is always prudent to round up when purchasing boards.

Joist Spacing for Diagonal Decking

A critical structural consideration for diagonal TimberTech decking is the joist spacing. Because the decking boards are oriented at an angle, they span across the joists differently than in a perpendicular layout. This can reduce the effective support provided by the joists, potentially leading to increased deflection or bounce if not addressed.

This tighter spacing provides the necessary support for the boards and helps maintain the deck's structural integrity over time. Always verify the specific joist spacing requirements for your chosen TimberTech product line in its installation guide.

This might necessitate adding extra joists to an existing frame or designing a new frame with this requirement in mind from the outset.

Fastening Systems and Edge Details

TimberTech offers both grooved and square-edge boards, compatible with hidden fastening systems or face fastening. For diagonal layouts, hidden clips are generally preferred as they maintain the clean lines of the diagonal pattern without visible fasteners. The hidden clip system creates a consistent gap between boards.

When installing diagonal boards, pay close attention to the perimeter of the deck. Picture-frame borders, created with square-edge boards installed perpendicular to the diagonal field, are a popular choice to provide a clean finish and define the deck's edge. These border boards can be face-fastened with color-matched screws and plugs for a seamless look. Alternatively, fascia boards can be used to cover the exposed ends of the diagonal boards, creating a finished edge.

Worked Example: Calculating Boards for a Diagonal Layout

Let's consider a hypothetical rectangular deck measuring 10 feet by 15 feet (150 square feet). We plan to use TimberTech boards that are 5.5 inches wide and available in 16-foot lengths. Each 16-foot board covers approximately 7.33 square feet (16 ft * 5.5 in / 12 in/ft).

For a perpendicular layout, we would typically calculate: 150 sq ft / 7.33 sq ft/board = approximately 20.47 boards. Rounding up, we'd need 21 boards.

For a diagonal layout, we must account for increased waste. Using a 20% waste factor: 150 sq ft * 1.20 = 180 adjusted sq ft. Then, 180 sq ft / 7.33 sq ft/board = approximately 24.56 boards. Rounding up, we'd need 25 boards. This shows an increase of 4 boards for the diagonal layout.

This example demonstrates the need for additional material. For accurate quantities, especially for complex deck shapes or specific board lengths, a detailed layout plan showing each board's placement and cuts is highly recommended. Always confirm the exact width of the TimberTech boards you intend to use, as this affects the square footage calculation.

Before you order

• Confirm the exact TimberTech product line and board dimensions.
• Calculate the deck's total square footage.
• Apply a 15-20% waste factor for diagonal cuts when estimating board quantity.
• Decide on edge finishing: picture-frame border or fascia.
• Choose between hidden fasteners or face fastening with plugs.
• Consider the visual flow and how diagonal lines interact with the surrounding environment.
• Consult the full TimberTech installation guide for specific product and fastening instructions.

Confirm installation details, approved uses and warranty terms in the current instructions for the exact product and profile. Your installer should verify the substrate, structure and applicable project requirements.

Questions to help you decide

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