ShadowDeck™ Installation Guide

Table of Contents

Planning Your ShadowDeck™

It is important to take some time to plan the layout of your ShadowDeck™. We recommend running the decking boards parallel to the house to highlight the timber and conceal the 3mm gap, but ultimately, it's a matter of personal preference.

Calculating Fasteners & Lineal Metres

To work out how many fasteners and the lineal metres of decking boards required, use the formula below.

Area (m²)
Width × Length = m²
Example: 3m × 4m = 12m²

One box will fasten 12 square metres using our Kwila 140mm wide decking.

Linear Metres in One Square Metre
1000 ÷ (board width + 3mm gap) × 1.1 (wastage)
1000 ÷ 143 = 7.7 linear metres per m²

Total Linear Metres Required
m² × 7.7 = Total linear metres
Example: 12m² × 7.7 = 92.4m

Note: You will also need to account for ShadowDeck™ 180×19mm fascia boards around the outside of your decking.

Board Spacing & Layout

The standard width of the decking boards is 140mm, on top of which you must allow a 3mm gap. Divide the width of the deck by 143mm (140mm board width + 3mm gap) to work out the number of boards required, adjusting as needed to ensure you use the full width of the decking boards from start to finish. This helps to avoid having to rip down any boards.

Make sure your perimeter joist ends 30mm shorter than your last decking board. This will allow the fascia board to tuck up nicely under the last decking board with a 10mm clearance.

Allow a 12mm space between the house and your first decking board. A ShadowDeck™ 12mm House2Deck Spacer makes this easy to achieve consistently.

Example Calculation

If you wanted to build a 2m deck out from your house:

  • 2000mm ÷ 143mm = 13.98 boards → round up to 14 boards
  • 14 × 143mm = 2002mm
  • Add 12mm house gap = 2014mm total deck width
  • Outside boundary joist = 2014mm − 30mm = 1984mm

This allows for a fascia board to be fitted to the boundary joist with a 10mm overhang.

Joist Spacing

If your decking boards run parallel to the length of the house, joists should run perpendicular to the house at 400mm centres. Once your boundary joists are in place, evenly space your joists at 400mm centres.

Picture Framing Considerations

Picture framing the perimeter of your deck gives a superior detailed finish. When picture framing with a picture frame board or a Bullnose board, you will need to add extra joists where the picture frame board and the butt ends meet. This picks up the ShadowDeck™ T-Shaped Fastener, which locates the picture frame board to the correct height. A second joist 45mm out from this joist is needed for a 3mm fastener. See Picture Framing Your ShadowDeck™.

Services & Structures

If you plan to add seating, handrails, or overhead structures, consider adding posts and framing to support the decking boards. For lighting, water, or gas services, plan ahead to have these utilities in place before your decking goes down.

For an estimate of how much timber and fasteners you need, use our online calculator at www.ShadowDeck.co.nz.

Transport, Storage and Handling

All decking timber should be kept dry until installation. Store on site in a cool, dry place, kept off the ground on bearers approximately 100–150mm high. If stored outside, cover with a tarp to protect from the elements.

Ventilation

Free air circulating under the deck is essential — it helps to minimise cupping and warping following installation. Proper ventilation minimises the difference in moisture levels between the top face and the underside of the decking, extending the life of the deck.

  • The underside of the deck should have at least 450mm clearance from the ground.
  • The ShadowDeck™ fastener provides an even 3mm ventilation gap between boards.

Note: Failure to provide suitable and adequate ventilation at construction is a major cause of early decking failure.

Installing the First Board

Once you have fixed your ribbon plate with the ShadowDeck™ 12mm House2Deck Spacers and finished framing your deck, you can start laying.

  1. Slide the first decking board into the ShadowDeck™ 12mm House2Deck Spacer.
  2. Tighten the first decking board using the ShadowDeck™ wrench.
  3. Insert a ShadowDeck™ Fastener into the slot and move into place using the joist locator on the fastener.
  4. Screw down at a 35–40° angle using the screws provided.

Important: Do not overtighten the screw — this will bend the lip of the fastener, making it difficult to fit the second board.

Installing Decking Boards

Using ShadowDeck™ 140×21mm pre-grooved domed decking, follow these steps for each board:

  1. Place a ShadowDeck™ fastener on top of the joist and slot it into the grooved edge of the decking timber.
  2. Move the locator pin so that it touches the side of the joist — this ensures the fastener and screw are centred on the joist.
  3. Use the ShadowDeck™ Deck Wrench to pull the decking board in tight and straight against the fastener. This creates a uniform 3mm gap between boards.
  4. Fix the fastener to the joist using the screws provided at a 35–40° angle.

Important: Do not overtighten the fastener — this will warp it and make the next board difficult to pull in. Work along each joist to ensure boards are pulled in tight and straight.

Repeat this process until you reach the last board.

Installing the Final Board

The final outside board is fixed in a similar way to the first board, with the inside face secured using a ShadowDeck™ Fastener.

To secure the outer edge of the final board, screw up at a 40° angle, 25mm down the boundary joist face. Repeat at 400mm centres along the boundary joist.

It is recommended to clamp the last board down while fixing it. You may also choose to use glue for added strength.

Tip: Use an off-cut to push the last board firmly into the fastener. Screw the off-cut horizontally into the boundary face to tighten the last decking board into the fastener. You can then screw up through the boundary joist into the bottom of the board to fix it down.

Installing the ShadowDeck™ Fascia Board

Once you have your 29mm overhang, you can install the first fascia board to the outside perimeter joist.

  • Screw and plug 20mm down from the top and bottom edges of the fascia board.
  • Glue can be used between the board and the joist for best results — this will reduce the number of plug & screws required.

Note: Fascia boards come in 180×19mm widths.

ShadowDeck™ Butt-Joint

[Diagram: ShadowDeck™ Butt-Joint — add image here]

Important: We do not recommend aristing the edges of your butt-joint using a plane, as this highlights your joints and channels water directly into them. This is an outdated technique that will shorten the life of your deck.

When building a ShadowDeck™, the aim is to blend the butt-joints, not highlight them.

The image below shows a finished ShadowDeck™ butt-end joint.

[Photo: Finished ShadowDeck™ butt-end joint — add image here]

ShadowDeck™ 12mm House2Deck Spacer

The ShadowDeck™ 12mm House2Deck Spacer creates a clean and tidy 12mm space between the house and deck, and helps pick up the first board — allowing water to drain away from the house effectively.

Use the House2Deck Spacer at 450mm centres along the ribbon plate. You will need a spacer at both the top and bottom of your ribbon plate to ensure it is square and level to the house.

Tip: To set the spacers at the correct height, use a pre-grooved off-cut decking board. Place the off-cut on top of the joist, position the House2Deck Spacer on the back of the ribbon plate, and insert the off-cut into the spacer so it sits flush with the top of the ribbon plate.

Once your spacers are screwed at 450mm centres, pre-drill through the centre hole using a 12mm drill bit. This hole is used to fix the ribbon plate to the wall with an M12 coach bolt and square washer.

Note: Please check current council requirements before fixing. Ensure your ribbon plate is level and square to the house — if not, pack out as needed to ensure your first board runs straight.

[Diagram: ShadowDeck™ House2Deck Spacer — add image here]

Picture Framing Your ShadowDeck™

Picture framing creates a beautiful border around the perimeter of your deck. This is achieved by creating a mitre join on each corner board and using a biscuit cutter with the 100mm Butt-Joint Biscuit supplied with your ShadowDeck™ Fasteners.

When picture framing, you will need to allow a 29mm overhang for a 140×21mm picture frame profile. This is an important decision as it determines the layout of your joists — getting this right at the start will save a lot of heartache later.

Important: It is critical to lay out your joists correctly so your butt ends finish on a joist.

[Diagram: Picture Frame Layout — add image here]

Ensure that the butt ends are straight and cut to the same length so the picture frame board butts up tight against them. For best results, use a rail plunge saw to cut the ends of the decking boards so they are all even and ready to receive the ShadowDeck™ T-Shaped Fasteners and the picture frame board.

Once you have inserted the ShadowDeck™ T-Shaped Fasteners into every 3mm gap, clip your picture frame board into these fasteners. The T-Shaped Fastener ensures the decking and picture frame boards are at the same height and adds strength to the joints.

Make sure your picture frame board is tight against the butt ends and held down using clamps. This is important to ensure the picture frame board is fastened tightly to your perimeter joist.

Fastening the Picture Frame Board

Once clamped, measure down from your perimeter joist outside face 25–30mm (approx.) and mark all the way along. Screw up at a 40–45° angle into your picture frame board.

Important: Avoid screwing through the face of your picture frame board.

Note: Most species of timber will shrink 1–2mm end grain over time. Ensure your picture frame board is hard up against your butt-end joins to account for this.

Screw & Plug Technique

In some cases you will need to screw through the top of a decking board. The best method for hiding these screws is to plug the hole for a clean, professional finish.

  1. Drill a pilot hole with a 4mm drill bit.
  2. Using a larger drill bit that matches your plug size, drill the same hole to a depth of 6–8mm only.
  3. Drive your screw into the hole so the head is countersunk by the same depth.
  4. Take an off-cut of the same decking timber and cut plugs using a plug cutter.
  5. Apply glue to the bottom of the plug. Align the grain of the plug with the grain of the board for a professional finish.
  6. Push the plug in by hand, then give it a couple of taps with a hammer.
  7. Allow the glue to set for the recommended time.
  8. Using a sharp chisel, trim off the excess plug flush with the surface.
  9. Sand the surface smooth and apply a small amount of decking oil with a clean rag or small brush.

Tip: Plug cutters are available at most good hardware stores. You can also speed up the process by using a 2-in-1 drill & countersink decking tool.

Teak Plugs are available in bags of 100 — the ideal ready-made solution for a consistent, colour-matched finish on Kwila and hardwood decking.

ShadowDeck™ Steps

Steps can provide safe access and great functionality to your ShadowDeck™. We recommend using three ShadowDeck™ 140×21mm decking boards wide to provide comfortable and safe access to your deck.

As with picture framing, ensure the last decking board overhangs the joist by approximately 30mm. If you are using the Bullnose profile, allow a 50mm overhang. It is important to lay out your framing to allow for this overhang before you begin.

[Diagram: Steps Layout — example 1258×448mm standard step layout — add image here]

[Diagram: ShadowDeck™ Step Close Up Side Profile — add image here]

Installing Step Fascia Boards

  1. Screw and plug 20mm from the top of the fascia board. Glue can also be used for extra strength.
  2. Once the fascia board is in place, biscuit cut into the bottom of it over the joist to set up for the next step. The minimum cut depth using a biscuit cutter is 8mm.
  3. The ShadowDeck™ decking is pre-grooved at 6mm from the bottom edge. You will need to pack the joist by 2mm to align the two slots for the fastener. Use 50mm×2mm Malthoid Bituminous as a packer (not PVC plastic).
  4. Insert the fastener into the fascia slot and screw down. Be careful not to overtighten and bend the fastener.
  5. Insert the next decking board and fasteners and continue the process.

Important: Do not fit all fascia boards first. The last decking board needs to be screwed up at a 40° angle before the fascia board is installed.

Repeat this process for each step, and screw and plug the last board if required.

ShadowDeck™ Picture Frame Step

For the ultimate finish, you can picture frame your steps. You will need to add additional framing to pick up the picture frame board, in the same way as you would for a deck picture frame.

[Diagram: Picture Frame Step — add image here]

Using a Bullnose Profile

A Bullnose profile can be used for seating, stairs, or deck edges, giving your ShadowDeck™ a softer, more refined look.

Allow an overhang as the Bullnose profile comes with a groove on the underside, specifically designed for a fascia board to slot into. You may need to pack out the fascia board to ensure a snug fit.

Fixing the Bullnose Board

  • For deck edges: screw up at a 40° angle, 25mm down from the top of the face of the perimeter joist, into the underside of the Bullnose board.
  • For stairs: screw from the bottom of the joist up into the underside of the Bullnose board. Use clamps to hold the board down while screwing to prevent it from rising.

Once fixed, slot a ShadowDeck™ 180×19mm fascia board into the underside groove of the Bullnose board. No fastening into the groove is required — glue can be used on the fascia board for added strength.

Tip: To ensure a snug fit into the groove of the Bullnose, use some Malthoid to pack out the step facing board.

Maintenance of Your ShadowDeck™

A ShadowDeck™ is designed to stand the test of time and give you and your family years of enjoyment. We strongly recommend cleaning and applying a fresh coat of ShadowDeck™ Decking Oil each year — more often depending on the deck's location — to keep it in peak condition. Decking oil provides a barrier against the elements and protects the wood, similar to the way sunscreen protects our skin.

Cleaning Your Deck

  1. Use a stiff brush to remove surface mould and clear the gaps between boards.
  2. Use a deck cleaner to remove any build-up of resin or extractives that may leach from the timber over time. If your deck is above another surface, be mindful of residue transfer.
  3. Allow the deck to dry completely before oiling.

Applying Decking Oil

Once clean and dry, apply a coat of ShadowDeck™ Decking Oil. For best results, apply 2 coats with at least 5 hours drying time between coats. A third coat applied three weeks later is also recommended.

Note: Boards should be free of all surface marks and stains before coating.

Tips to Keep Your Deck Looking Great

  • Do not place pot plants directly on the deck — use risers
  • Keep the deck free of leaves and debris
  • Move furniture regularly to avoid UV bleaching spots
  • Do not water blast at close range — this breaks away timber fibres and speeds up deterioration
  • Apply a coat of oil at least once a year to help the timber stand up to NZ weather

Tools Required for a ShadowDeck™

Essential Tools

  • Drop saw with fine tooth blade
  • ShadowDeck™ Deck Wrench
  • 18v Drill
  • Sharp chisel
  • Tape measure
  • Sharp pencil
  • Square
  • Plug cutter & drill bits

Recommended Tools

  • Plunge saw
  • Multi tool
  • Jigsaw
  • 2-in-1 drill bit
  • Caulking gun for wood adhesive

Safety Equipment

  • Ear plugs or ear muffs
  • Safety glasses or goggles
  • Gloves
  • Safety shoes

3×2m Deck Layout Example

Below is an example of a 3×2m deck layout with a picture frame.

[Diagram: 3×2 Deck Frame Layout Example — add image here]

[Diagram: 3×2 Finished Deck Layout Example — add image here]

Thank You!

Thank you for taking the time to review this installation guide. We know you will love your ShadowDeck™ for years to come. If you need any more information or want to request a quote, just click the link below and we will get back to you as soon as possible.

Get in Touch!