Building a deck
Who says natural is the only way to
go? Occasionally humans invent
something that not only lasts
longer than Mother Nature's products
but is easier to maintain. In
this article, we'll tell you how to use
some of these materials to build
yourself a deck that will last a long
time, look good and be easy to
maintain. We'll also show you
tricks and tips to make the building
process simpler and “mistake-tolerant.”
Decks are great do-it-yourself
projects, and this one, big as it
looks, is no exception. Although
this multilevel deck looks complex,
you can build it using standard
tools. A circular saw, drill, tape measure,
chalk line, hammer and posthole
digger can be adequate for building
anything from a simple 12 x 12-ft.
deck to an elaborate multilevel
structure. But don't think you'll
knock this one off in a couple of
weekends. This deck took 12
skilled-carpenter days to build, so
if you're new to carpentry, add a
few days for the learning curve,
weather delays, weekend-only
work and family obligations. Realistically,
a deck this size could turn
into a summerlong project.
Our deck is 420 sq. ft. and cost $8,500 (in 2000) including the planters and privacy wall. Using plastic composite decking (we used Trex) instead of cedar or treated added substantially to the project cost, but when you figure
that 15 years from now you'll be
vacationing in Mexico instead of
replacing the old deck, it doesn't seem
so bad. For decking material pros and
cons, see “The Case for Composite
Figure A: Main Deck and Assembly
Figure A shows the footing locations and framing details for the deck and the privacy fence. For a larger, printable version and a complete Shopping List, see Additional Information, below.
The key ingredients that will make your deck last (almost) forever
Decking: The floor bears the brunt of
rot on decks. Because deck boards lie
flat, water collects in cracks and knots and soaks into the end grain—especially
at splices. Because these areas
stay wet for long periods of time, they
are the most vulnerable to decay.
Although we used Trex for the decking,
we chose rough-sawn cedar lumber
for the privacy wall, planter trim
and other exposed wood to give the
project a more natural, tactile character.
Because these items are largely
vertical, they can be made of wood
and will last a very long time.
Lumber: The wood for all the above-ground
framing is .40-grade pressure-treated
lumber, which will last for
decades without any maintenance.
Posts and planter framing that are
underground call for foundation-grade
.60-treated lumber, the same material used for
wood foundations. Foundation-grade material
may be a special-order item in your
part of the country, but most lumberyards
can get it for you.
Hardware: Plan on spending a few
extra dollars to get quality hardware
designed for outside use. That means using double-hot-dipped galvanized
nails or, better yet, stainless steel nails
for all nailing, and exterior-rated joist
hanger nails. You can also use special screws designed for composite decking or buy hidden fasteners designed for decking, though these get expensive. Install drip cap above
the ledger and behind the siding (see
Photo 2). Don't scrimp on hardware;
remember that for the first time
ever, the structure could outlast the
Design: Take pains to plan your deck
for the long term. Think far into the
future to get the size and shape right.
Think in terms of a room addition
more than a deck. We hired an architect
and spent $500, a sum that
bought us a site visit, a couple of preliminary
drawings and final plans. He had numerous suggestions and ideas we
wouldn't have thought of. With the
design fee only 6 percent of the total
project, it was a bargain.
Footings: Make sure your footings are
deep and wide enough for your climate.
When you take your plans in to get a
building permit, your inspector will let
you know about the local requirements.
Here in Minnesota, that means 42-in.
deep footings, but we went 48 in. to
ensure that the deck would be able to
handle the next ice age.
Structure: Build with shorter spans,
narrower spacing and heavier materials
than you would for a normal, wood
deck. Our deck spans called for 2x10
beams and 2x8 joists, but we spent
about extra and upsized the structural members to 2x12 beams and
2x10 joists to give a more beefy, permanent
feel to what we expect will be
an outside living room.
Call 811 to locate and mark underground utilities before digging.
The soil at our site was a combination of loose sand,
rocks and hard clay, so we ended up using a power
auger, a steel bar to loosen rocks and a clamshell-style
posthole digger to extract the rock
and clean out loose soil at the bottom
of the hole. A drain tile shovel is
great for loosening the clay at the
bottom of the hole and for dislodging
Power augers cost about $70 - $90 per
day to rent, and they don't always
make posthole digging a quick, easy
chore. They take two strong people
to run, and they bog down in heavy soil and skip over
the top of any rocks bigger than a tangerine. They are,
however, worth their weight in gold if you have lots of
holes to dig—especially if you're digging in sandy soil.
The corkscrew end on the auger will extract the dirt
more efficiently than the clamshell digger because
sand falls through the end of the clamshell blades
when you're lifting the tool out of the hole. The
pros usually end up hand-digging about 40 percent
of the holes even if they do have a power
auger at their disposal. If you choose to rent an
auger, remember to hand-dig a pilot hole a few
inches deep before firing up the machine. Otherwise
the auger has a tendency to wander at startup and
your hole might shift several inches off your layout.
Use construction-friendly building methods
Follow the photo series for step-bystep
building techniques and keep
these labor-saving tips in mind when
planning and building your deck.
- We employed cantilevers (beams
hanging over posts, and joists hanging
over beams) in our design because
they make layout and construction
much easier. They also give the deck a
floating appearance by moving the
main structural supports in from the
deck's perimeter. Cantilevering also
helps by providing “fudge factors” throughout construction. They allow you to fine-tune the dimensions of the
deck as you build. Non-cantilevered
decks require exact placement of
posts at each corner from the moment
you dig your first posthole. Unfortunately,
all too often you discover only
after setting the posts that footing and
post placement is off by several
inches. You're then faced with living
with an out-of-square deck or making
some very time-consuming fixes.
- Begin construction by installing the
ledger board. (Don't forget the drip
cap! See Photo 2). Use the ledger for
laying out the rest of the deck, including
- Don't cut anything until you have
to. If possible, install members before
cutting them to length to give you the
opportunity to make minor adjustments in the structure as you build.
That means installing posts longer
than they have to be, running beams
longer than the deck is wide and
attaching joists to the ledger before cutting them to their finished length.
- Make your deck at least 6 in. smaller
than the standard 2-ft. increments of
lumber. We made our 12-ft. section of
deck 11 ft. 6 in. and our 16-ft. section
15 ft. 6 in. This lets you trim bad ends
on deck boards, maintain a 1-in.
overhang along the edges, and install
cedar trim boards to hide the treated
The Case for Composite Decking
Decks used to be built solely of redwood,
cedar or cypress because of
their inherent wood preservatives.
But as some of us have learned the
hard way, all wood eventually rots—especially in shady, moist locations.
For many years, preservative-treated lumber has
been the accepted material for a
long-lasting, rot-resistant deck. But
treated wood has its downsides too.
Besides not being particularly attractive,
it has a tendency to split, warp
and twist (and those treated splinters
embedded in the bottom of your
hoofs are no picnic either).
There are now alternatives to conventional
treated and natural wood.
Various manufacturers sell
different versions of plastic or
composite plastic/wood decking.
You'll find everything from basic, square-edged composites to elaborate space-frame
vinyl and fiberglass extrusions with,
of course, elaborate prices. Matching posts, railings and trim are also available for most types. These
products are not available in all
areas. You'll need to visit the lumberyards
in your area to see what your choices are. For more information on options, see How to Choose Composite Decking.
We chose Trex composite decking for this deck
because of its wide availability and
reasonable price. The decking material
we used is the classic 1-1/4 x 5-1/2
in. shape of conventional wood decking. (Visit trex.com to see the latest colors and styles.)
In addition to decking, many composites are available in a variety of non-structural
dimensions such as 2x6s and 2x4s,
which you can use for benches, rails
or privacy screens. Composite
decking is generally limited to 16-in. spans, so
the joists need to be spaced every
16 in. instead of the more common
24 in. used for wood 2x6s. Composite decking can be cut and drilled and shaped just like actual wood, so no extra tools are necessary.
Composites are denser and heavier
than wood. Consequently, they're harder
to haul around and a bit harder to
drive fasteners into. The good news
is that they won't split, warp, twist, cup or
crack—ever. The surface is skid-resistant
even when wet, and you'll get
that warm, fuzzy feeling knowing
that fewer trees gave their lives for
Splice decking with a single seam
The typical way to handle a deck that is wider than the deck boards is
to randomly butt the ends together
and split them over a deck joist. Cutting
and fitting all these joints takes
a lot of time and forces you to butt
two boards tightly together to share
the 1-1/2 in. thickness of a floor joist.
Nailing close to the ends makes
wood split and rot prematurely
because moisture gets into the
splice and doesn't dry out for long
periods of time.
A more elegant, longer-lasting
way is to create a single seam with a
dogeared length of decking perpendicular
to the deck itself. Then toenail
in another floor joist for nailing
the ends of the next section. Having
a full 1-1/2 in. of joist for nailing each
deck board allows for a space
between the end of the decking
board and the splice board for drying,
and helps keep nails away from
the splitting zone.
Construction details for planter.
Figure B: Planter
Planters make a striking addition to the deck, and also create more privacy, making the deck feel almost like a separate room. For a larger, printable version of Figure B, see Additional Information, below.
Back to Top
Think through the rail, planter and step details or they'll trip you up later
Most building codes call for 36-in.
high guardrails on any deck that's
more than 30 in. above ground and
any set of stairs that has more than
three risers. Our deck had only one
side higher than 30 in., so we decided
to handle that area with a 5-ft. privacy
wall (Photo 25) to provide a safety
rail and to screen the deck from a
nearby road. You can copy this design, or use the one shown in Deck Privacy Fence.
For the rest of the deck perimeter,
we built planter boxes in lieu of railings
(Photos 20 – 24) because we
didn't want our lake view obstructed.
We also liked the idea of being surrounded
by a deck-level flower garden.
Frame the planters like a conventional
stud wall made of
foundation-grade lumber and rest
them on a gravel footing. It's important
to make the planters freestanding.
The lack of a frost footing means they'll rise and fall with frost movement
and will lift the deck if they're
attached to it. Don't consider them
as legal guardrails but as a passive
barrier to keep people from accidentally
stepping off the edge. They were designed so the tops were 15 in.
above the deck to double as casual
Tips for laying out and cutting
deck stairs are available in How to Build Deck Stairs. We added
some cosmetic side stringers
(Photo 26) to dress the stair sides
and decked the treads with Trex.
Rest the steps on a gravel footing
topped with a treated 2x10 (Photo
26) using the same setting methods
demonstrated for the planters