How to Install Composite Decking for a Low-Maintenance Outdoor Space
DIY-savvy homeowners can build a low-maintenance deck in a few simple steps
Is your backyard hangout space looking worse for wear? Swap old wood decking and learn how to install composite decking for a wood look that’s easy to clean. When you finish your composite deck, less maintenance will give you more time to relax and enjoy the outdoors. Learn more about building a composite deck with simple power tools and basic DIY carpentry skills.
How to Prep for Composite Decking Installation
Make sure you have everything you need before building a composite deck, including a solid deck frame and all the necessary tools and materials. Consider the following prep steps:
1. Ensure You Have a Solid Deck Frame
You’ll need a solid frame with a maximum 16-inch joist span for composite decking. If you don’t already have a frame, follow our guide for how to build a deck to frame the structure and set posts in the ground. Adhere to local building codes when adding any kind of deck to your home.
If you have a frame in place, get under it with a flashlight and inspect weight-carrying joists and posts for rot, cracks, or pulling. Make sure joists are level and plane them down with a power hand planer if not.
2. Calculate How Much Decking Board You’ll Need
Take length and width measurements to calculate your deck’s square footage. Since decking is sold by linear foot in various dimensions, you’ll need to multiply the length and width of an individual board to find its board area. Divide your deck’s square footage by the board area and round up by 10% to account for waste. This result is how much decking you’ll need.
3. Synthetic Balusters and Handrails
You’ll also want to purchase synthetic balusters and handrails to match your decking. Many composite decking kits come with these materials and a hidden fastener system that automatically spaces boards for drainage and makes them easy to remove if needed. You’ll also need drills and saws to install and cut each board to length.
4. Gather All Tools Needed
With your decking board, balusters, and handrails ready, the last thing you’ll need to prepare for your DIY composite decking is tools. Below are a few tools for the project:
Power drill
Hand saw
Hammer
Framing square
Jigsaw
Circular saw
End nippers
Utility knife
Level
Goggles
Face shield
Tape measure
Pencil
Chalk
How to Install Composite Decking
Composite decking kits differ slightly between brands, but most contain similar parts, and you assemble them roughly the same way. Your kit will likely have specific instructions which you should follow closely for the best results. However, the process below is universal and will help you know what to expect.
1. Protect Your Frame From Rot
If you have a frame made from pressure-treated lumber, strengthen its rot resistance by rolling butyl tape over the top of each joist before installing decking.
Here’s how to protect your composite decking frame:
Choose a dark-colored tape that won’t be noticeable through the gaps between the decking boards.
Determine how much joist tape you need using a joist tape calculator.
Carefully press the tape across your joists.
Use a utility knife to cut the tape.
2. Fasten Start Clips
Start clips mark where you’ll push your first board. For each linear foot of decking material, you’ll need 0.75 start clips.
With that in mind, here’s what you need to know to fasten the starter clips to your joists:
Start on the side of the frame that sits against your home. If you’re installing composite decking on a floating deck, you can start on any side.
Position a start clip flush with the edge of the frame on top and in the center of the joist.
Using one composite decking screw per clip, fasten each start clip into the frame.
3. Attach First Decking Board
Your first decking board is perhaps one of the most important parts of laying your deck because it sets up the rest of your deck. Be meticulous when completing this step to install your deck correctly.
If you have a downspout to account for, use a jigsaw to cut a hole for it on your first board. Wear protective gear like goggles and a face shield when using power tools.
Push the decking board into the start clips so that they fit tightly into the board’s side groove.
On the opposite side of the board, where the board meets each of the frame’s joists, push a clip prong into the exposed side groove.
Screw these clip prongs into the first board through the center of the joists.
Ensure your board is straight and securely attached before moving on to the next steps.
4. Attach the Rest of the Decking Boards
Get your puzzle skills ready because this next step involves connecting the decking boards on your frame. Here’s how to attach your composite boards:
Cut your next decking plank to length using a circular saw.
Secure another start clip.
Push this board into the clip you just attached so they fit tightly into the side grooves.
As with your first row, screw clip prongs into the opposite side of the row.
The clips should automatically space your boards for proper drainage, but ensure the space between each board is at least ⅜ inch apart to accommodate for heat expansion.
Repeat this process to install the boards until you have only one board left.
5. Attach the Outer Decking Board
Your outer decking board may not need to be full width, so follow these steps to attach the outer decking board correctly.
Measure and cut along the length of the deck if needed, notching it to fit around any posts as necessary.
Use chalk or a pencil on the final joist to mark where the edge of your last board will lie by adding the width of your remaining two boards and the width of the gap between them.
Use the markings to line up and attach starter clips at each end of the frame and on top of joists at regular intervals, like when you attached the first board.
Depending on the clip design, you may need to use end nippers to remove the spikes from one side.
Click a board in place against these clips.
Then, clip prongs onto the next-to-lastboard.
6. Measure and Cut Decking to Length
It’s time to fine-tune your new deck. Wear protective gear like a face shield and goggles when using a saw to avoid getting debris in your face, then follow these steps:
Snap a chalk line across your deck boards in line with the edge of the frame where the boards are hanging off.
Use a screw to fasten a straight-edged board along your line to act as a saw guide.
Guide a circular saw along the straight edge to trim your decking to length.
Remove your straight edge and fill the screw hole with wood putty.
7. Attach the Fascia Finish
Many composite decking products are not the same color through the board, so you’ll want to cover the ends to give your decking a flush finish. Here’s how to add a finish to composite decking:
Measure and cut your composite fascia pieces to size using a saw.
Screw the pieces onto the ends of your frame at regular joist intervals to cover the exposed frame and composite ends.
Tips for Taking Care of Composite Decking
Composite decking is a long-lasting material and resists many types of damage typical to natural wood. However, even low-maintenance decking needs proper care to stay looking new. Use these tips to clean and maintain your composite decking.
Minimize moisture: Redirect downspouts and dryer vents away from the deck and by clearing away standing puddles with a mop or floor squeegee.
Ventilate your deck: Ensure there’s at least 6 inches of unobstructed airflow underneath your deck.
Proper mulch storage: Don’t store organic mulch on, under, or against your deck.
Add protection: Use woven rugs and avoid mats that have a rubber backing, which can trap moisture.
Mind the gaps: Unclog gaps between boards when leaves or grass build up.
Weekly maintenance: Sweep often to prevent debris from getting caught in gaps, especially during autumn.
Regular cleanings: Scrub and rinse your deck with mild water, soap, and a gentle scrub brush if sweeping won’t remove dirt, grease spills, or salt build-up.
DIY vs. Hire a Pro
If your frame is in good condition and you have the necessary skills and experience, you’ll spend between $2,100 and $5,200 on a DIY composite decking project. Compare that to the cost of professional installation by a deck builder near you, which averages $3,600 to $7,200. Keep in mind that hiring a professional deck builder will ensure your composite decking installation goes smoothly and quickly.
Plus, while you might save on labor, DIY mistakes can lead to costly repairs and even personal injury. Be sure your substructure can support the weight without shifting before attempting to DIY. If you decide to hire a pro, get at least three quotes, read online ratings and reviews, and get an in-person consultation before you make a decision.
Nick P. Cellucci contributed to this piece.
Frequently Asked Questions
You need a solid subframe base for composite decking. Your frame can be built from composite, plastic, timber, or metal joists as long as your base can support its weight without shifting. When hiring a professional deck builder, discuss whether they recommend installing the frame for your composite decking on top of a solid concrete base.
You can nail or screw composite decking, though three-inch decking screws are the better fastener choice. Unlike nails, decking screws won’t back out of the composite material over time. There’s also little danger of splitting composite material when driving screws, so you don’t need to pre-drill holes unless otherwise recommended by your decking manufacturer.
The problems with composite decking include a high rate of expansion and contraction from temperature swings. This characteristic can cause boards to split, delaminate, or peel. In addition, significant movement can cause shrinking, warping, twisting, and bending. For this reason, you should minimize moisture and ensure proper airflow below your deck.