Floating deck
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Simple design goes together fast
The simplicity of this
deck makes it fast to
build. With a helper and
all the materials ready to
go first thing in the
morning, you can have a
completed deck before
sundown. If you add a
step to your deck and
use hidden deck fasteners
as we did, you might
need a few more hours
to finish the job.
Most decks are attached to houses, but there’s
no reason they have to be. Sometimes the best
spot to set up a deck chair and relax is at the
other end of the yard, tucked into a shady corner
of the garden. And if you don’t attach the
deck to the house, you don’t need deep frost
footings—which can save hours of backbreaking
labor, especially in wooded or rocky areas
where footings are difficult to dig.
We designed this deck with simple construction
in mind. If you can cut boards and drive
screws, you can build it. The only power tools
you’ll need are a circular saw and a drill, though a miter saw also helps. We used a premium grade of low-maintenance
composite decking with hidden fasteners, which
brought the total cost to over $2,000, but using standard
treated decking and screws would cut the cost by more than half. You may need to special-order composite decking and hidden fasteners if
you use the same types we did, but everything
else is stocked at home centers or
lumberyards.
A few cautions: If all or part of the deck
is higher than 30 in. off the ground, you’ll
need a building permit and railings. If you
intend to build any kind of structure on
top of the deck or attach the deck to the
house, you also need a permit. If you dig
footings, call 811 first to check for underground
utilities. Also, keep the deck at
least 4 ft. back from the property line.
Figure A: Island Deck
The dimensions of this deck are 11-ft. 8-in. square, not including the stairs.
A complete Materials List and Cutting List is available in pdf format in Additional Information below.
Place the footings and beams
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Photo 1: Layout and leveling
Lay a quick foundation
with minimal digging
by setting concrete blocks
on gravel. Level from
high to low spots with
a string level.
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Line level
Stretch a mason's string between stakes at the high and low point, then hang a line level on the string and move it up and down to establish level.
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Photo 2: Square the beams
Take diagonal
measurements and
tap one beam forward or
back to square the beams.
Temporary stretchers hold
the beams parallel.
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Photo 3: Attach angles
Screw on angle
brackets at each
joist location instead of
toenailing, which can split
and weaken the joists
and knock the beams
out of square.
Lay out the two beams parallel to each
other, 9 ft. apart. Screw on temporary 1x4 stretchers across the ends of the beams,
overhanging them each the same distance,
then measure diagonally to make sure the
beams are square to each other. Mark the
location of the gravel pads (see Figure A)
by cutting the grass with a shovel, then
move the beams out of the way and cut
out the sod where the gravel will go.
Establish the highest and lowest points
with a string and string level to get a
rough idea of how deep to dig and how
much gravel to put in to make the blocks
level (Figure A). Tamp the dirt with a
block to make a firm base, then spread the
gravel. Place the blocks and level them
against each other and in both directions
(Photo 1), adding or scraping out gravel
as needed. Use construction adhesive
between the 4-in.-thick blocks if you stack
them, or use 8-in. blocks. If your site
slopes so much that one side will be more
than 2 ft. off the ground, support it on a
4x4 post on a frost footing instead—it’ll
look better and be safer.
Set the beams across the blocks and
square them to each other, using the same
1x4 stretchers to hold them parallel and
square (Photo 2). If the beams are not
perfectly level, shim them with plastic shims (sold in
home centers).
Mark the joist locations on the beams,
starting with a joist on the end of each
beam. We used 11 joists spaced 12 in. on center to keep the composite decking we used from sagging over time, but wood
decking can be spaced 16 in. on center.
Instead of toenailing, which often splits
the wood, use metal angles to hold down
the joists. This also makes it easy to place
the joists. Attach one alongside each joist location (Photo 3).
Cantilever the joists on all sides
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Photo 4: Install the joists
Install the middle and
end joists, then screw
on the rim joists, using
clamps (or a helper) to
hold them in place.
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Photo 5: Add corner blocking
For strong connections
at the corners, set
corner blocking between
the last two joists, then
nail the rim joist from
both directions.
Set the two outer joists and the center joist
on the beams against the metal angles.
Extend the joists over the beam on one
side by 10-1/2 in., but let them run long
over the opposite beam. Trim them to
exact length when the deck is almost done
so you can avoid ripping the last deck
board.
Fasten the joists to the angles with deck
screws. Screw on both rim joists—you’ll
have to take the second rim joist back off
when the joists are trimmed and then reattach it, but it’s needed to hold the
joists straight and to hold the outside
joists up (Photo 4). The decking will hold
the outside joists up when the rim joist is
removed later.
Set the other joists on the beams and
fasten them to the beams and rim joists.
Reinforce the outside corners with additional
blocking (Photo 5). Finally, mark
the center of the joists and run blocking
between each pair of joists. Set the blocking
1/2 in. to the side of the center mark,
alternating from side to side, so that the
blocking doesn’t end up in the gap
between the deck boards.
Add a step
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Photo 6: Add steps
Frame the steps
next. You can avoid
additional footings by
hanging stringers from
the deck joists with
metal angles or 2x4s.
The deck surface should be no more than
8 in. above the ground where you step up
on it. If it’s close, just build up the ground
or add concrete pavers. Otherwise, add a
step.
To cantilever the stairs, extend the stair
stringers underneath four deck joists, then
join the floor joists and stair stringers with
reinforcing angles (as we did) or wood
2x4s, which are less expensive (Photo 6).
Use a screw first to hold the angles or 2x4
blocks in place, then finish fastening them
with nails, which have greater shear
strength.
The 5/4 (nominal) decking we used called for a maximum
spacing between stair stringers of
9 in. on center, but you can space stringers
16 in. on center if you use solid wood.
Hidden fasteners create a clean look
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Photo 7: Attach decking
Attach the deck
boards. Decks look
best when you use hidden
fasteners, but they make
installation slower. Trim
the deck boards flush with
the rim joist when you're
done.
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Photo 8: Screw on the skirt board
Wrap the deck
with skirt boards
that match the decking,
driving trim head screws
just below the surface
at the spacer locations
(see Figure A).
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Photo 9: Finish the steps
Screw skirt boards to
the sides of the steps
for a finished look, then
measure, cut and attach a
riser board to the face of
the steps.
We attached the deck boards with hidden
fasteners (see Materials List in Additional Information below). Other types
of hidden fasteners are available—or you
can use deck screws, which create lots of
holes but save time and money.
Start with a full board at one side, aligning
it with the edge of the rim joist. Leave
the boards long at both ends, then cut
them back later all at once so the edges are
straight. Use four 1/4-in. spacers between
each pair of boards as you fasten them,
but check the distance to the rim joist
after every four boards and adjust spacing
if necessary.
At the next to the last board, remove the
rim joist and mark and cut the ends off
the joists so the last deck board lines up
with the edge of the rim joist. Reinstall the
rim joist and attach the last boards.
Nail 1/4-in. spacers ripped from treated
wood to the rim joist every 16 in. so water
won’t get trapped against the rim joist.
Screw on skirt boards with two screws at
each spacer (Photo 8). Attach the decking
to the steps after the skirt boards are fastened.
Finally, finish the steps (Photo 9).
