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Badly damaged slab
A concrete slab in this condition has to be either broken up and carted away or decked over.
This was the ultimate bad patio:
severely cracked and cratered, some
areas raised by frost, others sunken after
50 years of settling. Originally, it was tiled,
then the tile was chiseled off and the
pockmarked surface got a coat
A slab with this much damage can't be
fixed. But it can be covered up—and this
article will show you how. The results
look just like a deck, but getting them is
much easier and less expensive than
building a deck from scratch. In most
cases, this project is also less expensive
than a new patio installed by a contractor.
Local contractors estimated costs of
$7 to $10 per sq. ft. to remove this patio
and pour a new slab. You could probably
replace your patio yourself for less than
the cost of this project, but DIY demolition
and concrete pours are big, backbreaking
Will It Work On Your Patio?
Even if your patio is in terrible shape, you can deck over it. Cracks, craters and
seasonal movement along cracks are no problem. But beware of these three
- If an area is badly cracked and sinks noticeably year after year, any decking you put over it will also sink and develop a low spot. In most cases, settling concrete stops sinking eventually, so delay this project until it does.
- This project raises the level of your patio by 2-1/2 to 3-1/2 in. (depending on the thickness of your decking and whether or not you put spacers under the sleepers). So any door thresholds adjoining the patio must be at least that far above the concrete. If not, this project won't work for you. If you live in a climate where the ground freezes, allow an extra 1/2 in. so that seasonal “frost heave” can raise the slab without damaging the threshold.
- Stairs connected to the patio can complicate this project. To keep step heights
equal, you'll have to raise the treads by the same distance you raise the patio
(2-1/2 to 3-1/2 in.). On concrete steps, that's a straightforward job: You can
treat them just like the patio, screwing sleepers to the treads and risers and
decking over them.
Time, money and tools
Covering a patio with decking typically
takes a weekend or two. This patio took
much more time—five long days. That's
partly because it's a big one (14 x 28 ft.).
The grid pattern formed with different-colored
decking also added a few hours to the job. But the biggest time factor
was the unevenness of the patio surface.
All those ridges and sunken spots meant
hours of tedious shimming under the
sleepers to form a flat surface for the
decking (see Photo 3).
The cost of this project depends
mostly on the decking you choose.
Decking ranges from about $1.50 per sq.
ft. for treated wood to more than $10 per
sq. ft. for a top-grade manufactured
product. The other materials for this
project add up to about $1.50 per sq. ft.,
so your total cost could be anywhere from $3 to $12 per sq. ft. For looks and
durability, we used two different colors of decking made from PVC, but there are less expensive alternatives.
Aside from standard carpentry tools,
you'll need a hammer drill for this project.
You can get a hammer drill for less
than $50 that will do the job. But consider
spending $100 or more. Even a very
small patio will require more than 50
holes, and a more powerful drill will
make that chore a lot easier. Also consider
buying an impact driver. Impact
drivers pack a lot more torque than
standard drills or drivers and will drive
concrete screws much better. Most
models are cordless, but you
can still find inexpensive corded models online.
Figure A: Deck over a patio
Figure A: Deck Over a Patio
screwed to the
you to screw on
and flashing tape
protect sleepers from
moisture and rot. Fascia
boards hide exposed edges
for a neater look.
For a, printable version of Figure A, see Additional Information, below.
Plan the layout
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Photo 1: Start with a layout
Mark the sleeper locations on the patio. Don't forget
about extra sleepers to support stairs or railings.
The layout of your sleepers will depend on
the layout of your decking. If you want a
standard decking design—all the deck
boards running one direction—all you
need are rows of parallel sleepers. If you
want a more complicated decking pattern,
like the one shown here, you'll need doubled
sleepers to support any boards that
run perpendicular to the others (see Figure
A). We also installed sleepers to support
the steps we later added to the concrete
stoop (see Photo 1).
Solve Water Problems First
This corner of the patio had settled by
more than 2 in. over the years. That
meant a big reservoir after rain—and
water in the basement. So we filled
the reservoir with exterior-grade self-leveling
compound. After the first
batch hardened, we poured on a thin
coat and gave it a slight slope so
water would run away from the house.
Self-leveling compound hardens
fast, so you can get on with the project.
But it's also expensive. If you're not in a rush, you can
get similar results for less than one-third
the cost with concrete topping
mix such as Sakrete Top 'n Bond or
Quikrete Sand/Topping Mix.
We also took a couple of other
water-fighting steps. To prevent
water from seeping down along the
foundation, we caulked the gap
between the patio and the house. At
the other end of the patio, a corner of
the slab had sunk slightly below the
level of the soil and rainwater pooled
there. To correct that, we shaved off
the sod with a spade, dug out a couple
of inches of soil and replaced the sod.
Lay the sleepers
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Photo 2: Predrill for concrete screws
Drill through sleepers, spacers and into the concrete with
a hammer drill, then drive in concrete screws. Overhang the
sleepers along one edge of the patio and trim them to exact
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Photo 3: Screw down and flatten the sleepers
Check for flatness with a straightedge. Raise low spots with
shims. At high spots, skip the spacer; stack up shims instead.
The sleepers don't have to be level‐they
can follow the slope of your patio. But
they do need to form a flat plane. If your
patio is in good shape, you'll get a flat
plane automatically. If your patio has
ridges and sunken areas, you'll spend lots
of time fussing with shims.
To preview the situation, lay a straight
board across the patio in a few spots. Look
for the highest hump in the patio and
fasten your first sleeper there. Then work
outward from the high spot, adding sleepers
and checking for flatness along each
sleeper and across them. Add shims to
raise low spots.
Screwing down sleepers with concrete
screws (Photo 2) is simple, but there are
some things to keep in mind:
- Screws should penetrate the concrete
by at least 1 in., so 3-1/4-in. screws are
perfect. In low spots, where we had to
stack up shims, we switched to 3-3/4-
- As you drill, dust compresses around
the drill bit. That slows you down,
strains your drill and overheats the bit.
To clear the dust, pull the bit completely
out of the hole once or twice while drilling
- Drill the holes 1/4 to 1/2 in. deeper
than the screw will reach. Extra depth
provides a space for dust and grit, so
screws are easier to drive.
- Have extra drill bits on hand. As a bit
wears, it doesn't just drill more slowly;
it also bores a slightly smaller hole and
screws become harder to drive. We
replaced each bit after about 40 holes.
When all the sleepers are screwed down,
take a few minutes to double-check for
flatness. Set a 4-ft. straightedge on each
sleeper, both across it and along it. If you
find spots that are 1/16 in. or more out-of-plane,
back out the screw and add or
remove shims (Photo 3).
Why Use Spacers?
You could lay your sleepers directly on
the concrete, but we bought a 1/2-in.-
thick PVC trim board and cut spacer
blocks from it. Here's why:
- Spacers let you run sleepers parallel
to the house so decking can run perpendicular
to the house (if that's
what you prefer). A patio typically
slopes away from the house so that
water runs off. If you run sleepers
parallel to the house and set them
directly on the concrete, each sleeper
will block runoff. But with spacers,
water can run under the sleepers.
- Spacers allow for longer decking
screws. We wanted to use Cortex
screws, which come with cover plugs
made from the same material as the
decking. They're easy to use and
almost invisible. But they're 2-3/4 in.
long; that's too long to sink into our
decking if we use sleepers only.
- Spacers let the sleepers dry out. If
kept damp, common grades of
treated wood will eventually rot.
Spacers keep the sleepers off the
damp concrete so they can dry.
Install the decking
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Photo 4: Lay the decking
Install the deck boards just as you would on a standard
deck. When you reach the end of the patio, position the last
board, mark the overhanging sleepers and trim off the excess.
Before decking, we covered the sleepers
with flashing tape. Without it, water soaks
the tops of the sleepers and the decking
prevents the wood from drying. Common
grades of treated lumber will rot if kept
permanently damp, and flashing tape is
the best insurance against that.
Installing deck boards over sleepers is
just like installing them over standard
deck framing (Photo 4). We began with the
darker “accent” boards, screwing them into
place temporarily to act as guides for the
“field” boards. When we reached the end of
the deck, we removed the center divider
board and cut it to final length. Then we
removed and mitered the border boards
and trimmed the sleepers to final length.
To cover the ends of the sleepers, we
used a deck “fascia” board made from
1/2-in.-thick PVC. We cut the fascia into
strips and screwed them to the sleepers.
Aside from the decking, here's an estimate of what you'll
need to cover 100 sq. ft. of patio. Exact quantities depend
on the shape of your patio and the layout of the decking.
- 90 linear ft. of treated 2x4
- 90 linear ft. of flashing tape
- Sixty 3/16” x 3-1/4” concrete screws
- 1/2”-thick PVC trim or deck fascia (for spacers), plastic
shims, 3/16-in. masonry drill bits (minimum drilling
depth of 3-1/2 in.)
Keeping it simple
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The simpler you can make your deck plan, the faster and cheaper it will be to build.
For a, printable version of Basic deck, see Additional Information, below.
If you're a beginning DIYer, don't let all the details on
our deck scare you away. Your project can be
a whole lot easier if you choose a
simple decking design like the one
at right. With all the deck boards
running in the same direction, all
you need are sleepers centered 16
in. apart. You won't need to do the
careful measuring required by our
design, or make angled miters and other
fussy cuts. A simple deck design makes this
project almost impossible to get wrong. If you
have a badly uneven patio like ours, flattening the
sleepers with shims (Photo 3) may take hours. It's
tedious but not complicated.
You can slash the cost by using treated wood deck
boards instead of manufactured decking. And if you live in a
drier climate where the sleepers won't stay damp, you can skip
the spacers and flashing tape.
More Ways to Improve a Patio
Whether your patio is in
bad shape or just bland,
there are many ways to
revive it. But before you
weigh the options shown below, there's
one thing to consider…
The crack factor
Cracks in your patio drastically limit your options. That's because cracks tend to move.
Some grow wider over time, while others shrink and widen as the soil freezes and thaws.
Some become uneven as one side of the crack sinks. Any movement happens so slowly that
it's hard to detect. But if you know—or even think—that you have moving cracks, you have to
choose a patio upgrade that can “float” over moving cracks without becoming damaged.
More cover-ups for a cracked patio
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Bury it under pavers
A concrete slab provides a firm,
stable base for pavers. Cover the
patio with a thin layer of sand, lay
pavers over it, and the results look
like a standard paver patio. It's a
fairly simple project and the cost is
reasonable ($3 to $6 per sq. ft.), but
expect a weekend or two of hard
labor. For complete step-by-step
instructions, see How to Cover a Concrete Patio With Pavers.
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Hide it under a rug
The quickest way to hide damaged concrete—or just add
color—is with an outdoor area rug. They're available in a huge
range of colors, designs and prices. The largest
rugs are typically 9 x 12 ft. That may not cover your entire patio,
but just covering most of an ugly patio makes a huge difference.
Shop online or visit a store that handles patio accessories.
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Interlocking plastic tiles simply snap together; no need to
fasten them to the patio. Less expensive versions are plastic only.
Others are topped with wood, ceramic or stone. (Ceramic
or stone tiles require a flat surface—they may crack if
installed over ridges or depressions.) To browse online,
search for “deck tile” or “patio tile.”
Along with the deck project shown on the previous pages, here are some other projects that can withstand moving cracks:
Projects for a crack-free patio
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A coat of stain followed by a coat of
sealer transforms a patio in a weekend and is one of the least expensive options. But there are
downsides: You'll have to reseal every
one to three years and may eventually
have to restain it. Also, stain won't hide
damage, and any repairs will likely
show through the stain. To see how to
apply stain in multicolor patterns, see Renew Your Concrete Patio.
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A concrete patio is a great foundation for tile. And tile is a
great way to turn a bland patio into a showpiece. The cost
depends mostly on the tile you choose; the project could
cost $4 per sq. ft. or three times that. Freezing water can
destroy outdoor tile, so if you live in a climate that freezes,
pay extra attention to the details. For the complete story,
see How to Build a Patio With Ceramic Tile.
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With a coat of resurfacer, you can make an old patio look like new
concrete quickly and cheaply. Just mix the cement-based
powder with water and spread it over the patio. You can repair
cracks and resurface over them, but the cracks may return. Quikrete
Concrete Resurfacer and Sakrete Flo-Coat are two common brands.
If your patio isn't cracked, you could choose any of the options above or either stain, tile or resurface the concrete.