Platform Deck

Platform deck

Before you start, follow this checklist for pre- construction planning:

1. Gain a deck construction overview with videos and tips on all aspects of the process.

2. Call your local building code enforcement office to discuss footing depth, deck location limits, if you need a weed barrier under your deck, handrail requirements, necessary permits, and what inspections will be needed along the way when building your project.

3. Check any neighborhood conveyances or covenants for special rules in your neighborhood governing the deck you intend to build.

4. Once you have an idea where your deck can be located, call 811 for a free service to locate underground utilities.

INSTRUCTIONS:

Footings and Rim Joist

Step 1: After reviewing the layout of the deck, start by setting batter boards and string lines (Project Diagram, Drawing 1) using the second “How to Lay Out a Deck” video as your guide. After the hole centers are marked with a stake, you can pull down the string lines, but leave the batter boards in place for later.

Step 2: Dig 8-inch-diameter holes to the frost depth in your region at each center point. With the holes dug, mix enough concrete to fill the five holes — one in each corner and one in the middle of the deck. Make the tops of the footings even with the ground at each hole (Project Diagram, Drawing 2).

Step 3: Remove the grass from the area under your deck, lay down landscape fabric, and cover it with approximately 2 inches of decorative stone. This will keep the area under the deck looking nice and prevent grass from growing below the deck.

Step 4: Set the strings back up and use a plumb bob from the string corners to mark the center of each post on the concrete footings. Set post base plate anchors at each center point and anchor to the concrete with 1/2-in-diameter concrete wedge anchors.

Step 5: Cut 4 x 4 posts (A) to about 4 inches longer than what is needed for the deck to attach the posts. Level the string lines to determine the lengths of the four corner posts.

Step 6: Secure the post in the anchors according to the manufacturer’s instructions and cut the perimeter boards to length. Then cut the deck ends (B) and sides (C) (Project Diagram, Cutting Diagram) to fit the project as you proceed to account for any variances. With the help of a friend, clamp the rim boards so their bottom edges are 2 inches above the ground at the highest point of the ground. Once each board is level and flush with the adjoining boards, drive 3-inch deck screws to hold them in position.

Step 7: Reinforce the board to posts connection by drilling 1/2-inch holes and adding two 1/2-inch carriage bolts, washers, and nuts (Project Diagram, Drawing 3) to each connection.

Step 8: Cut the top of the post flush with the perimeter boards using a reciprocating saw, after cutting the post, you can concentrate on the framing (Photo 1).

Assemble the perimeter frame of the platform deck

Setting the Joist

Step 1: Lay out the center beam (D) locations (Project Diagram, Drawing 1) centered on the ends and screw double joist hangers to the ends. Place the two center beams in the hangers, but do not attach them yet. Locate the midpoint of the beams and mark the center point of the center post on the concrete footing and measure for the length of the center post. Now remove the center beam.

Step 2: Anchor the center base plate and secure the cut center post to the base plate. Re-insert the center beams into the joist hangers (Photo 2) and secure the beam to the joist hangers and the center post-beam connectors (Project Diagram, Drawing 4).

Add the center beam to the deck.

Step 4: Mark the locations of the short joists (E) (Project Diagram, Drawing 5). Cut them to fit and secure them to the perimeter boards and the center beam with joist hangers (Photo 3).

Install the cross joist

Step 5: Now add the long joist (F) ( Photo 4). Secure the hangers to the frame and joist with fasteners that are approved by the hanger manufacturer, such as the #8 x 1-1/4-in joist hanger screws in the buying guide.

Add joists to each quadrant of the deck.

Step 6: To complete the framing of the deck, each quadrant needs one more joist. These pieces, the long filler (G) and short filler (H) (Project Diagram, Drawing 6), support the ends of the deck boards and the edges of the perimeter deck boards. Cut the blocking joist to fit and install by driving nails at a angle, called toe nailing, into the post and cross beams (Photo 5). The fillers are spaced 3/4 inch from the ends (B) and sides (C).

Add the final joist to each deck quadrant.

Band Boards and Decking

Step 1: To conceal the treated deck framing, use cedar 1 x 12s around the perimeter (Project Diagram, Drawing 6). Mark the center of each side of the deck and then cut the ends of the short fascia (I) and long fascia (J) at 45-degree angles. Clamp them to the deck and mark the corners of the deck where they need to be mitered to wrap the deck (Photo 6). Then nail the boards to the deck. Continue your way around the frame to complete the fascia boards.

Wrap the perimeter of the deck with cedar

Good to Know: If boards are simply butted together at the joints, gaps will form as they expand and contract with changes in moisture. By cutting these boards at an angle, called a scarf joint) (Photo 7) and joining them, the joints are concealed and any gaps become invisible.

Install the perimeter wrap boards using scarf joints.

Step 2: Cut 5/4 x 6 deck boards for the perimeter decking, parts (K) and (L) (Project Diagram, Drawing 7) so that each board overhangs the cedar fascia by 1-1/2 inches and is mitered at the ends (Photo 8). Fasten them in place with stainless-steel trim screws.

Add the perimeter decking

Step 3: Cut and install the center deck board and the two center cross boards using 2-1/2-inch coated deck screws (Photo 9; Project Diagram, Drawing 7).

Add the center deck board and the two center cross boards

Step 4: Cut the remaining deck boards to fit each quadrant and install with screws (Photo 10; Project Diagram, Drawing 7). Lay the boards in each section, they may need to be slightly gapped to create and even deck pattern without the need to rip a narrow board to fill any gap. The max spacing of the boards should be about 1/8-inch.

Add the remaining deck boards

Step 3: With the decking complete, allow the deck materials to dry for one month before applying a preservative. With a big, flat surface like this, a paint roller speeds up the job.

PROJECT DETAILS

Skill Level: Intermediate

Estimated Cost: $1085 + paint

Time Estimate: 1 Weekend

Tools:

  • Shovel
  • Wheelbarrow
  • 5-lb hammer
  • String-line level and string
  • 4-ft level
  • Hammer
  • Hammer drill with 1/2-in bit
  • Posthole digger
  • Cordless drill with bits
  • 1/2-in x 6-in drill bit
  • Powered miter saw

Materials:

  • Download Pattern
  • See Cutting Diagram for lumber:
  • 4 – 2 x 2 x 8 furring strips, #4513
  • 2 – 1 x 3 x 8 furring strips, #4512
  • 10 – Quikrete 80-lb concrete mix, #10385
  • 10-ft x 25-ft black 6-mil plastic sheet, #16924
  • 20 – Quikrete 50-lb. all-purpose gravel, #10439
  • 5 – 1/2-in x 3-1/2-in wedge anchors, #63683
  • 5 – 4 x 4 post bases, #108719
  • #9 x 2-1/2-in coated deck screws
  • 16 – 1/2-in x 6-in galvanized carriage bolts, #67357
  • 16 – 1/2-in galvanized washers, #67342
  • 16 – 1/2-in galvanized hex nuts, #67449
  • 2 – double 2 x 8 joist hangers, #107903
  • 2 – Simpson 4 x 4 twin post caps, #51759
  • 4 – #8 x 1-1/4-in joist hanger screws, #92853
  • 36 – 2 x 8 joist hangers, #108806
  • 2 – 8d galvanized casing nails
  • Stain or finish

* Items may be Special Order in some stores. Product costs, availability, and item numbers may vary online or by market. Paint colors may vary slightly from those shown. Availability varies by market for lumber species and sizes.


 

Products and prices may change; check your local Lowe’s store for details

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