Framing a Floating Deck

Check the factory end of the board to make sure it’s square, and cut the board to length at the line with a circular saw. Use the same process to cut the other rim joist, and cut the 2-inch-by-6-inch center beam to length to run between the two side joists. Cut the 2-inch-by-6-inch lumber for floor joists, side joists and end joists to length.

With the framing cut to length, lay out the boards for the floor joists, marking where they’ll attach to the beam and rim joists. Center and clamp the beam between the rim joists, making sure that the center of the beam aligns to the center of the rim joists. Clamping them together this way holds them securely aligned so you can accurately mark the floor joist locations on each board.

Measure 16 inches out from the center point and mark. Continue measuring and marking 16 inches out in both directions along the rim joist to mark the center points of the other floor joists. Once you have the joist locations marked along the rim joist, use the speed square to transfer the marks across all three framing members.

On one of the rim joists, locate the marks you made for the center points of the side joists, and use a framing square to transfer the marks down the outer face of the board. These lines will mark where you fasten the rim joist to the side joists. Predrill screw holes along the line, with the top and bottom holes about an inch from the edges of the board.

Position the rim joist with the line at the center of one of the side joists. Make sure the top edges of the rim joist and side joist are even, and drive in coated deck screws to fasten them together. Repeat the process on the other end of the rim joist, and attach the second rim joist to the side joists in the same way.

Measure along a side joist half the distance between the two rim joists — for this deck it’s 83-1/2 inches — and mark. Adjust the support blocks as needed to align the middle of the beam with this mark. Repeat the process at the other end of the beam.

Add the other concrete support blocks for the center beam. Make sure everything is level, and secure the beam to the side joists with screws.

Check the perimeter framing for square by using the diagonal method as you did in Floating Deck Plan and Layout above. For this deck, the measurements between the opposing corners are each 206-1/2 inches. Since they’re equal, the frame is square.

Lock the frame together in square across each corner with temporary 2-inch-by-4-inch braces fastened to the frame with screws. Check the frame for level.

Align the joist hangers to the marks and install them with the appropriate joist hanger nails or joist hanger screws. Make sure the bottom of each hanger is flush with the bottom edge of the beam. Per codes, every fastener hole in the joist hanger needs to have a fastener. Install all of the joist hangers on your beam and rim joists.

Remove the temporary corner braces on one side of the center beam. Place the concrete blocks that'll support the floor joists along the rim joist, near the joist hangers. Test fit one of the intermediate floor joists, placing it in the joist hangers and on the block. Adjust the block as necessary for the joist to rest level so the top edge is flush with the edges of the beam and rim joist. Check the remaining blocks and adjust as necessary. Repeat the process on the other side of the center beam.

Begin placing the intermediate joists in the hangers. The boards will have a slight upward arch or crown along one edge. Place each joist with the crown edge up. Secure the floor joists in the joist hangers with joist hanger screws or nails as you did above. Remember there must be a fastener in each fastener hole.

Cut the framing pieces to length to run between the floor joists. We’re cutting four pieces to double the framing on each side. Cut out the bottom of the inner pieces a little bit using a jigsaw to give the tree a bit more room to grow.

Use double joist hangers to install the framing and further secure with nails or screws running through the floor joists.

For larger trees, or longer joist spans, double up the framing all around the tree. You can use special hangers to attach framing at the corners.

Add the sleepers — the short boards running between the double-end joist and the side joist — to provide extra support.

Install corner brackets inside the frame, securing the rim joists to the double-end joist. Make sure the fasteners are appropriate for the brackets. Install the double-end joist and supports on the opposite side of the deck.

Put the step pieces in place. Check for level front to back and side to side. Adjust as needed.

Attach the front step assembly to the rim joist. Clamp a side step assembly to the front step assembly, making sure they're flush to each other. Use deck screws to attach the side assembly to the double-end joist. Repeat the process on the other side of the deck.

If any of the joists are a little high, use a power planer to even them out.

Apply waterproof tape to the top of the framing. This will help protect the wood and protect against any ice or water that might get in between the deck boards.

Wire mesh or hardware cloth along the edge of the deck will keep small animals from getting under the deck. Attach small blocks just inside the outer frame to support the mesh. Cut the mesh to the correct height and staple it to the blocks.