deck with several types of mood lighting
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How to Add a Little Mood Lighting to Your Deck

Use energy-efficient LEDs to cast a warm glow on the deck, stairs, and trees, and you can extend the party (safely) into the night

Decks are usually built with summer days in mind, but the entertaining doesn’t have to stop when the sun goes down. Installing outdoor-rated LEDs can illuminate your space in a way that promotes both safe footing and appealing ambience—versus the harsh shadows you get from a spotlight on the house.

“Low-voltage lighting is very DIY-friendly,” says Scott Caron, master electrician for Ask This Old House. “The thin wiring is easy to hide on or under the deck.” In addition to putting up festive string lights, he installed three kinds of LEDs on this deck in San Antonio, allowing the homeowners to enjoy their Lone Star evenings. For your own project, start by deciding where to place the transformer, which steps the power down to 12 volts: It needs to plug in to a standard 110-volt outlet, and all your wiring routes back to this point.

Step One // How to Add a Little Mood Lighting to Your Deck

Project Overview

illustrated exploded view of deck lighting
Illustration by Gregory Nemec

Timeline:

Day 1: Install the lights (Steps 2–9).
Day 2: Wire the lights to the transformer (Steps 10–14).

Post light, $92; LED ledge and rail light, $107; up/down light, $128; all in copper, from Focus Industries

Steps // How to Add a Little Mood Lighting to Your Deck
1 ×

Project Overview

 
Step One // How to Add a Little Mood Lighting to Your Deck

Project Overview

illustrated exploded view of deck lighting
Illustration by Gregory Nemec

Timeline:

Day 1: Install the lights (Steps 2–9).
Day 2: Wire the lights to the transformer (Steps 10–14).

Post light, $92; LED ledge and rail light, $107; up/down light, $128; all in copper, from Focus Industries

 
2 ×

Drill a Hole for Wiring

 
Step Two // How to Add a Little Mood Lighting to Your Deck

Drill a Hole for Wiring

Scott Caron drilling a hole for wiring
Photo by Matthew Mahon

Mark the center of a post about 12 inches above the deck—high enough for the light to illuminate the decking but not so high that it will blind seated guests. Use a paddle bit to drill a inch-diameter hole through the post, as shown. Repeat for every post.

 
3 ×

Screw on Post Light

 
Step Three // How to Add a Little Mood Lighting to Your Deck

Screw on Post Light

Scott Caron attaching a post light
Photo by Matthew Mahon

Fish the LED wire through the housing and fresh hole. Attach the fixture to the post with supplied screws, as shown. Secure the wire to the back side of the post with low-voltage staples. Continue stapling every few inches, carrying the wire to the next fixture by tucking it under the handrail or the deck’s framing (you’ll wire it later).

 
4 ×

Build Out the Treads

 
Step Four // How to Add a Little Mood Lighting to Your Deck

Build Out the Treads

Scott Caron installs tread lighting for a deck
Photo by Matthew Mahon

The stairway lights mount to the treads overhanging the risers. If your tread doesn’t have an overhang of at least 1 inch, add one with a 2x2 pressure-treated pine baluster. Measure the width of the tread and cut the piece to fit with a circular saw. Evenly space pilot holes along the front edge of the baluster for 2-inch deck screws. Attach the fixture to the middle of the baluster with supplied screws, as shown, then repeat the process on the remaining treads.

 
5 ×

Drill a Pass-Through

 
Step Five // How to Add a Little Mood Lighting to Your Deck

Drill a Pass-Through

Scott Caron passes wiring through a deck stair tread
Photo by Matthew Mahon

Drill a inch-diameter hole in the riser just below the tread to accept the fixture’s wire. Fish the loose end of the wire into the hole, as shown. Repeat the process on the remaining treads.

 
6 ×

Fasten the Fixture in Place

 
Step Six // How to Add a Little Mood Lighting to Your Deck

Fasten the Fixture in Place

Scott Caron attaches the fixture to the deck stair tread
Photo by Matthew Mahon

Add a bead of polyurethane adhesive to the baluster, then screw the baluster to the tread, as shown, oriented with the LEDs facing the step below. Repeat this process on the remaining treads, then stain the balusters to match the deck.

 
7 ×

Cut a Hole

 
Step Seven // How to Add a Little Mood Lighting to Your Deck

Cut a Hole

Scott Caron cutting a hole in decking with a hole saw
Photo by Matthew Mahon

Locate uplights in the center of deck boards about a foot from the tree to illuminate the bark and the canopy. Use a 2-inch hole saw to cut a hole for each light.

 
8 ×

Add Lights

 
Step Eight // How to Add a Little Mood Lighting to Your Deck

Add Lights

Scott Caron adds the uplights to the deck
Photo by Matthew Mahon

Thread the wire into the hole, then press-fit the light in place.

 
9 ×

Strip the Wires

 
Step Nine // How to Add a Little Mood Lighting to Your Deck

Strip the Wires

Scott Caron strips some wires for deck lighting
Photo by Matthew Mahon

Use 14-gauge wire to daisy chain all the lights of a certain type together—post lights to post lights, for example. To start, use wire strippers to remove about an inch of insulation from the wires attached to the light farthest from the transformer. Measure the distance between this light and the next one and cut a length of 14-gauge wire to that length. Split the 14-gauge wire apart, then strip all four ends.

 
10 ×

Add Compression Connections

 
Step Ten // How to Add a Little Mood Lighting to Your Deck

Add Compression Connections

Scott Caron adds compression connection to the lighting wires for deck lighting
Photo by Matthew Mahon

Insert the first light’s ribbed or marked negative wire into one end of the brass compression connection and tighten the set screw with a hex wrench, as shown. Slip the heat-shrink tubing over the connection, then add the ribbed 14-gauge wire to the other end of the connection and tighten it. Repeat the process on the smooth or unmarked positive wires of the same fixture.

 
11 ×

Shrink the Wrap

 
Step Eleven // How to Add a Little Mood Lighting to Your Deck

Shrink the Wrap

Scott Caron uses a heat gun to insulate the connection for deck lighting
Photo by Matthew Mahon

Cover the connection with the heat-shrink tubing, then pass a torch or heat gun over the wrap, holding it a few inches away, to form a watertight seal, as shown. Continue daisy chaining lights in the series until you reach the one closest to the transformer. Add enough 14-gauge wire to reach the transformer, and secure the connections with waterproof wire nuts. Now join the three 14-gauge wires (positives together and negatives together) and add another section of 14-gauge wire to serve as a pigtail. Hide the wiring under the deck or secure it out of sight with staples.

 
12 ×

Mount the Box

 
Step Twelve // How to Add a Little Mood Lighting to Your Deck

Mount the Box

Scott Caron mounts the transformer box for the deck lighting wire source
Photo by Matthew Mahon

The bottom of the transformer must be at least 1 foot off the ground and within 2 feet of a standard 110-volt outlet. We placed ours inside the house to keep the timer easily accessible. First, use deck screws to attach the mounting bracket to the wall, checking for level with a torpedo level. Attach the transformer to the bracket.

 
13 ×

Wire the Box

 
Step Thirteen // How to Add a Little Mood Lighting to Your Deck

Wire the Box

Scott Caron wiring the transformer box for deck lighting
Photo by Matthew Mahon

Bring the pigtail to the box and thread it through the knockout in the bottom, as shown. Use a small flathead screwdriver to tighten the negative wire into the terminal labeled “common” and the positive wire into the 12.5-volt terminal. Plug the transformer into the 110-volt outlet, then flip the switch to test the lights. Set the timer and install the cover.

 
 
 
 

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