Whether they're elaborate entertaining spaces that cost $40,000 or
simple pressure-treated platforms that cost 10 percent of that, all
aboveground-pool decks have tricky angles to work with. Over the
past few years, my company has created systems that allow us to
build some pool decks off-site in a shop, which keeps costs down
and helps us outbid other deck builders while maintaining decent
The first and foremost factor to consider when laying out a pool
deck is safety. Each year, about 300 children under the age of 5
drown, and more than 2,000 are hospitalized for submersion
injuries. If an accident happens, much of the liability falls on
the homeowner. However, if building codes were not followed,
liability falls on the builder as well. Requirements vary locally;
gates, guardrails, fences, and alarms are all safety devices that
may be part of your local building codes and must be taken very
seriously. Never even be tempted to build a pool deck without
permits, and be sure you understand your local requirements before
Access and Other Considerations
After safety, the next consideration is providing access to the
mechanical parts of the pool. Most aboveground swimming pools have
one main pump, jet, and filter, plus a skimmer. The pump and the
filter need to be accessible for routine cleaning and
winterization. The skimmer is generally flush with the surface of
the deck or a couple of inches below and has a prefilter - to keep
large contaminants like bugs and leaves from entering the pump -
that requires regular cleaning. Also, pool vacuums generally plug
into the pool skimmer for suction. Avoid framing directly over any
of these items, and make sure there are a few inches of clearance
to access any mechanical parts. Always get your hands on the pool
manufacturer's manual before designing the deck. There may be
certain construction guidelines or restrictions that can void the
homeowner's pool warranty if not followed properly.
"Where do I put all of my pool accessories?" is a common question
among homeowners looking to build a pool deck. If they don't have a
pool house, they usually need a place to store the chemicals, the
vacuum hose, and a net. Often we'll create a storage space under
the deck for tools and chemicals. Chemicals can be put in a
weatherproof box made from scrap PVC decking. The pool hoses and
nets can be stored on hooks that screw into the posts and beams in
On the recreational side, the owners need a place for the
inflatables, diving rings, and other pool toys. These are used more
often than the cleaners, so I offer to build the owners a bench
with a hinged seat and tie-off points to keep the inflatable toys
from blowing all over the yard when they aren't in use.
Pool deck location is very important. If the pool stands alone,
decks that don't wrap all the way around usually can be put
anywhere around the pool. If the pool is located in a partially
shaded part of the yard, it is critical to understand where the sun
is at the time of day the pool will generally be used. Some
homeowners prefer a shaded area and some prefer the sun. Some
decking gets a lot hotter than others, while other decking will
become very moldy very quickly in a shaded area. I've had good
success with Azek (877/275-2935, azek.com) and TimberTech PVC
(800/307-7780, timbertech.com) decking around pools. And because of
the corrosiveness of the pool chemicals, it's a good idea to use
stainless steel for all the hardware and fasteners, although that
can be a tough sell in a competitive market.
If the owners are going to use the pool at night, I offer
low-voltage ambient lighting. Be careful when wiring, though. Some
lighting and speaker companies have their own guidelines for wiring
near water that go beyond the local building code. And some
jurisdictions require even low-voltage wiring near a pool to be
installed by a licensed electrician.
Rectangular Pool Decks
I build pool decks with beams and cantilevered joists (as opposed
to structural rim beams) for a couple of reasons. When the outside
and inside rims are used as beams, the footing locations need to be
perfect or the posts won't hit the corners properly; with beams and
cantilevered joists, you have more flexibility. Also, when framing
an aboveground-pool deck, it's important to keep the footings at
least 12 inches away from the walls of the pool, and a structural
rim would require footings right next to the pool. It isn't good to
undermine the pool walls with a footing hole because it's very easy
to puncture the vinyl liner with a shovel. And if the electrician
has already done his job, there may also be a continuous grounding
wire close to the edge that we don't want to cut.
My company builds mainly two types of aboveground-pool decks. One
is a large rectangular deck around an oval pool (see illustration).
All the decking gets installed in the same direction, and the
footing and railing installation is the same as for any other
rectangular deck, but with angled sections that go around the
The tricky parts are handled simply with cantilevers and blocking.
A pair of beams run parallel to the long wall of the pool, and
shorter beams handle the load at the short end. Near the curve of
the pool runs an angled beam, over which joists cantilever toward
the pool. My crew will set all of the joists except the outer two
without trimming them to length. Once all joists are set, a chalk
line is snapped from one end to the other and the joists are cut to
length in place. Angled blocking between joists, with a minimum
2-inch clearance from the edge of the pool, keeps the framing from
twisting and provides solid nailing for the decking.
Round or Polygonal Decks
Most aboveground-pool decks my company builds are polygonal decks
that wrap a series of trapezoid modules around a "circular" pool.
Most of the time, when someone refers to a circular aboveground
swimming pool, the only round part is the wall - the pool frame
itself is a polygon.
The trapezoid modules can be built off-site if you have a rainy
week ahead of you. Their modular construction also means they can
easily be taken apart in the future if there is a problem with the
swimming pool. The smaller 8- to 10-foot-deep modules fit the
budget for many people. With this size, one carpenter can frame and
deck two modules, pre-assemble handrail sections, and prebuild the
stairs in one day off-site. If you use footing blocks (because pool
decks are freestanding, the IRC does not require frost footings),
two to three modules (complete with rails and stairs) can be
installed in one day with a three-person crew (27 hours).
Laying Out Polygons
The biggest challenge with polygonal pool decks is layout. For the
math, I use a Construction Master calculator (Calculated
Industries; 800/854-8075, calculated.com). You can do it with any
calculator, or with a pencil and paper, but because the
Construction Master is specialized (it calculates in feet and
inches, for example), it's really the way to go. The company even
has smartphone apps.
To keep the math simple, I am using as an example a deck that
projects 8 feet from the rail of the pool, but the same
mathematical process applies to decks of any depth. Most "circular"
aboveground pools have between 12 and 19 equal-length sides that
make up the top rail (this is what we build the deck against). In
the example, the pool has 16 sides (a hexadecagon). No matter the
number of sides, the pool shape is a regular polygon - a polygon
whose sides are all the same length and whose angles are all the
same. The math in this section can apply to many angled decks, not
just pool decks.
The deck itself is a series of trapezoids - basically truncated
wedges. To find the angles at which the trapezoids will be
constructed, we need to find the interior angles of the polygon
(see illustration, above). The number of polygon sides determines
the angle of the trapezoid modules. The sum of all interior angles
in a regular polygon equals 360°. Thus, 360° divided by the
number of sides yields the interior angle.
360° ÷ 16 = 22.5° per section
The angle where the joists intersect the slanted sides of the
trapezoid will be half of the interior angle.
22.5° ÷ 2 = 11.25°
The angles at the far end of the trapezoid are the complement of
that angle (see illustration, below).
90° – 11.25° = 78.75°
As with any deck, you need exact site measurements before you can
generate a footing layout and cut lists for beams, joists, and
rims. The depth of the deck (distance from the pool) in this case
was 8 feet. The length of the pool sides is the starting point for
all other dimensions; here, the length of one side is 4 feet 8 1/4
Calculate the Outside
Once we know the angle, length against the pool, and trapezoid
depth, we can figure the outside dimensions of the deck module. To
make it very easy, break the trapezoid into two equal right
triangles and one centered rectangle (see illustration,
The first length to find is a in the illustration - the short side
of the right triangle. Using a Construction Master calculator, type
11.25 [Pitch] 8 [Feet]
a = 1' 7 1/8"
Without clearing the screen, hit [Diag] to get the
length of side b in the illustration.
b = 8' 1 7/8"
To find the length of side c, multiply a by 2 and add the length of
the side against the pool, 4' 8 1/4".
(1' 7 1/8" x 2) + 4' 8 1/4" = 7' 10 1/2"
c = 7' 10 1/2"
Start a Cut List
With the lengths of the perimeter sides determined, we can start
generating a cut list for the module. I label each part with a
letter - R for rims, J for joists, B for beams - and a
Starting with the rims, I number each piece clockwise. R1 and R3
run the total width of each end of the trapezoid and R2 and R4 are
installed between those.
All of the rim pieces are cut at a bevel, so I label the points
where the measurement is taken for each cut: LP = long point, SP =
short point, S = square cut.
The lengths of R1 and R3 are taken from the previous example. To
find the length of R2 and R4, subtract the thickness of R1 and R3
from the length of side b from the previous example (8' 1 7/8"). On
a square deck, we would normally subtract 1 1/2" for the thickness
of the rim joist. However, since these joints are at an 11.25°
bevel, we need to figure the thickness of the material at the
bevel. Using the Construction Master, enter:
11.25 [Pitch] 1 1/2 [Inch]
[Diag] = 1 9/16"
The material is 19/16" at an 11.25° bevel.
To figure the total thickness of R1 and R3, multiply 19/16" by
1 9/16" x 2 = 3 1/8"
To figure the length of R2 and R4, subtract 31/8" from the overall
length of side b.
8' 1 7/8" – 3 1/8" = 7' 10 3/4"
The length of R2 and R4 is 7' 10 3/4".
Calculate Joist Length
Next, I number the full-length joists as J1 and the short side
joists as J2 and figure out their lengths. J1 is easy. Just as you
would with a square deck, subtract the thickness of the two rims
(3") from the overall depth (8').
J1 = 8' – 3" = 7' 9"
One end of J2 is beveled; figure the length to the long point. This
will take a few steps. Starting on the side against the pool,
measure the distance from the closest J1 joist to the inside point
at which R1 and R2 (or R1 and R4) join. In this case, the distance
measures 11 1/2".
We also need the length of d. Our joist layout is 16" on-center, so
we know the distance between joists is 14 1/2".
To find length d:
14 1/2" – 11 1/2" = 3"
d = 3"
Enter d as the rise into the Construction Master.
11.25 [Pitch] 3 [Inch]
[Run] = 15 1/16"
Subtract 151/16" from the length of J1 (7' 9") to get the
measurement of J2.
J1 – 15 1/16" = J2
7' 9" – 15 1/16" = 6' 5 15/16"
J2 = 6' 5 15/16"
Calculate the J2 Bevel
The bevel on J2 differs from the bevels of the rim. The angle of
€†J2's bevel is the complement of 11.25°
(complementary angles add up to 90°). To find the angle of
€†J2, subtract 11.25° from 90°.
90° – 11.25° = 78.75°
Calculate Beam Lengths and Footing
I usually make beams from two pieces of 2-by. In cases where the
ends of the beam are beveled, as in the illustration, I calculate
the length of the center of the beam. Figuring to the center gives
me the length to the long point of the bevel on the shorter piece,
and the short point of the bevel on the longer piece. For these
modules, I keep the center of the beam 1 foot in from R1 and 1 foot
in from R3.
To find the lengths of B1 and B2, first find the lengths of e and
f. We know the distances from B1 and B2 to R1 (1' and 7',
respectively), and we know the pitch.
Find B1 on the Construction Master:
11.25 [Pitch] 1 [Feet]
[Rise] = 23/8"
Distance e = 2 3/8"
Without clearing the screen, push [Diag] to get
the distance along R2 from the edge of the pool to the center of
the first footing (F1) .
[Diag] = 1'01/4"
Distance to center of F1 = 1 '0 1/4"
Find the center length of B1 by multiplying e by 2 and adding it to
the length of R1.
(2 3/8" x 2) + 4' 8 1/4" = 5'1"
B1 = 5' 1" (center length)
B1 is made up of two pieces: B1a measures 5'1" between its long
points, and B1b measures 5'1" between its short points, at an
Follow the same Construction Master steps for B2 and F2 using 7' as
11.25 [Pitch] 7 [Feet]
[Rise] = 1' 4 11/16"
Distance f = 1' 4 11/16"
Without clearing the screen, push [Diag] = 7' 1
Distance to center of F2 along R4 = 7' 15/8"
(1' 4 11/16" x 2) + 4' 8 1/4" = 7' 5 5/8"
B2 = 7' 5 5/8" (center length)
Laying out the footings around a pool can be a real pain. Many deck
builders have a hard time finding and calculating the angles, never
mind trying to keep batter boards and strings in place. But another
great thing about working with trapezoidal modules is the easy
footing layout. We already know how far each footing needs to be
from the corner of the pool. All that's needed now is the angled
layout line that the footings fall on. Instead of pulling out a
calculator and trying to calculate hypotenuses, we do the
following, depending on whether the pool has an even or odd number
For even-sided pools, I have one crew member hold a string at the
corner opposite the corner we'll be building from (below left).
Another crew member runs the string directly across the pool to the
side we are building from, pulling the string through the corner of
the pool and about 10 feet beyond. This is the exact line the deck
frame will follow. A third person measures off the corner of the
pool with a tape, and down from the string with a plumb bob to
locate the centers of the footings.
If the pool has an odd number of sides, the crew member opposite
the deck side holds the end of the string centered on the opposite
side of the pool, rather than at a corner (below right). The rest
of the process is the same as for even-sided pools.
Putting It Together
Now we have a complete cut list for the deck framing, along with
footing locations. These should not vary, and you can build as many
modules as are called for. There are several bonuses to these
ˆ™ You can build them on a rainy day in a
ˆ™ If the owner wants to make the deck bigger
down the road, adding another module is easy.
ˆ™ If there is a problem with the pool, the
modules can be unbolted from each other and taken apart for
ˆ™ You can build them at a comfortable working
I have had a lot of luck selling these modules as replacement decks
for older aboveground pools, and I've also had luck selling them
with new pools. My company has a display deck at one of the larger
aboveground-pool distributors, and we offer bundle pricing with
each pool. –
Rob Arnold owns Efficient Exteriors in