1.) Decks, a multitude of designs and as many ways to build them. I will describe how to
build a deck that is less than 4' off the ground with handrail and stairs and attached to an existing
structure. You will want to refer to this batter board
before you proceed. It will
also be necessary to know how to crown lumber on this project. All horizontal framing members placed on
their edge, such as joist, need to be crowned.
This is accomplished by simply looking along one of the two narrow edge from one end to the other and if you
see a hump along its length, that is a crown. This should not to be confused with a bow which is a curve
along the wider side of the board. It is possible for a board to have both a crown and a bow. However, it
is easier to straighten a bow than a crown. I will discuss this more later. If a crown is present, it must
be placed with the crown facing upward. If a board is placed with the crown facing down, it has a greater
chance of sagging when a load is applied. A crown in excess of 1/2" in 12' is not acceptable and should be either
replaced or cut into shorter pieces.
2.) Decide where the right side of your deck should be and put a mark on the existing wall. This is
point(A) where the string will start.
3.) Measure from the first mark along the existing wall to where you want the deck to end and place a
second mark. This is point(F) where the string will end.
4.) Determine where you want or need the finished height of the deck including the surface.
•Measure down the thickness of the surface and place a mark on the wall, this will be the height of your deck frame.
•Use a level or better yet, and especially for larger decks, use a water level and place a mark at the frame height beyond
point (A) and point (F), See batter bourd example above.
•In this example the height of the frame is 45" from the ground, then snap a chalk line from one mark to the other.
•Using at least the same dimension lumber as the joist or larger, cut the ledger board 3" shorter than the overall
length needed to allow for the two end joist to fasten to the each end of the ledger (see ledger board drawing).
•Layout for the joist before laying out for the bolt hole locations being careful not to have one interfere
with the other.
•Drill 9/16" bolt holes through the ledger board about 24" apart and stagger the holes.
•Either have someone hold the ledger to the wall or temporarilly fasten to the wall flush to the bottom of the chalk line
and transfer the marks with a pencil.
•Drill appropriate sized pilot hole depending on the material your fastening to and the type of bolt your using.
•If fastening to concrete, an expansion bolt will work well. For a 1/2" expansion bolt you would drill a 1/2" pilot hole.
•The same is true if your fastening to wood using either 1/2" carriage or hex bolts with nuts and washers.
•If your fastening to wood with lag bolts and washers, you would drill at least a 1/4" pilot hole but not over 3/8".
5.) With the ledger secured, tack a nail to the top right corner of the ledger board at point(A) and attach a string. Extend the
string to a nail tacked into the top of batter board #1 at point(B).
Make sure all strings are tight.
6.) Measuring from the wall near point(A), subtract 1-1/2" from the desired distance you want the deck to extend out and place a mark
on batter board #1 at point(C) and tack another nail. Be sure to deduct 1-1/2" which is the thickness of a outer box joist.
7.) Repeat this last step Measuring from the wall near point(F), and place a mark on batter board #2
at point(D) and tack a nail. Again deducting 1-1/2"
8.) Attach a string from point(C) to point(D).
9.) Measure from point(B) to point(E) the same length as the ledger board, place a mark
and tack a nail and attach a string between these two points.
10.) Attach the last string from point(E) to the top left corner of the ledger board at point(F).
•Take a diagonal measurement from the end of the ledger where it meets the wall at point(A) to where the strings
cross at batter board #2 and record this measurement.
•Next measure from the end of the ledger where it meets the wall at point(F) to where the strings cross at batter board #1.
•Compare the two measurements and if the first measurement, at point(a) to batter board #2 is greater, move the nails securing the strings at points(B) and (E) an equal distance to the right exactly 1/2 the difference
in the measurements.
•If the second measurement is greater move points(B) and (E) to the left in the same way.
Lets clarify this. Lets say the first measurement (point A to where the strings cross at batter board #2) is 302"
and the second measurement (point F to where the strings cross at batter board #1) is less at 300", move the nails and strings at point B and E exactly 1" to the right which is 1/2 the difference.
If the second measurement were 2" more than the first, you would move the string to the left 1".
Check the diagonal measurements again, they both should be 301".
11.) Wood being what it is, even treated wood required for residential use today, should be protected from insect and
decay. It is a good idea to coat all surfaces that will be below grade(ground level). I use an emulsified tar and coat
all surfaces that will be buried, then wrap with 4 to 6 mill polyethylene plastic sheathing. When setting posts, surround
all sides and bottom of post in concrete filling hole above grade and slope concrete away from post to prevent water from
12.) Plan where to put your posts using this
illustration as a guide. Locate posts 5 to 6' apart and only place them near the string but not so close
as to push the string. For deck construction where the deck is not more then a few feet tall, dig post holes
a minimum of 18" deep and 6 inches in diameter larger than the size of the post. Fill the bottom of the hole
with 5 to 6" of concrete and mix with water. Press two 6" pieces of #4 reinforcement bar into the concrete at
opposing angles to form an X and let concrete setup for awhile. This reinforcement may not be required
but will add to the strength of the concrete under the post plus support the post while the concrete is not
completely setup. Use a water level to determine the rough length of each post. Posts that will carry the
railing need to be 36" to 42" taller than the top of the ledger board. All others need to be no taller than
the height of the ledger. A row of posts
under the floor that carry a beam to support long joist would be cut the same height as the bottom of the
box joist or ledger. Cut a post a few inches longer then is required and set into the hole. Attach a
post setting level and while holding the post
near the string, plumb the post and fill hole with concrete and water then dig additional holes and set all
remaining posts in the same way. If you determined a center beam is required setup a string and dig additional
holes. This table may help determine the allowable span for joist of a given spacing.
These specs are approximate so consult your local building codes.
Also consider most building codes will require 16" on center joist spacing for a 5/4" deck board.
The question here should be, if I want to span 14' with my joist is it less expensive to use
2x10 joist or use 2x6 joist with a center beam. I would recommend always use a center beam for
low to moderate height decks and save the larger joist for second story applications.
You may if you wish, premix your concrete but it is not necessary. You can install it as described
and it will setup even without mixing. Be sure to plan a location for your stairs for which you will
need a minimum of 36" between posts.
13.) After the concrete has setup, check all strings for tightness and mark each post where the
string passes next to it. Keeping in mind the string can sag over long distances and allowance may
need to be made. Set your box joist around the perimeter flush to the bottom of this mark and any
breaks must fall on the center of a post. Be sure to fasten the two end joist to the end of the
ledger. All posts carrying the railing measure and cut a minimum of 36" taller than the box joist.
Other post not extending through the floor, cut to the same height as the box joist. If post are
ment to carry a center beam under the floor, those post need to be cut off at the same height as
the bottom of the joist.
14.) If your using a center beam, fasten a framing member of at least the same dimension as the joist
to the front and back of the center row and flush with the top of each post, repeat for any remaining
rows. These are to support the joist and need to extend from one box joist to the other. Any breaks
must fall on the center of a post and stagger the break on a different post on the other side.
15.) The box joist that carries the end of the common joist needs to be doubled for extra support
so add another member of the same dimension between each post,
(see example). Now layout the double
box joist to match identically with your ledger board. Measure and cut each joist and tack into position.
Install hangers and fasten joists secure. Be sure to crown the joist before nailing into place.
Straighten all joist before nailing to any center support beams.
16.) Check out this example
to get an idea of the mechanics behind designing a basic set of stairs.
Measure from the ground to the top of the deck frame as it is now and let's say it is 45".
Add the thickness of your deck surface to be installed later and let's say that is 1-1/2"
for a total of 46-1/2". Let's also say that 7-3/4" is the maximum height allowed for a step.
So deviding 46-1/2 by 7-3/4 gives you 6 steps or risers total. Referring to the example just
presented, you will see six risers and 5 treads or runs. We are going to use 11" run for each
tread so 5 runs at 11" equals 55" from where the stairs start at the box joist to where they
end. Place a mark at 55" out and using either a straight 2x4 and a level or a string and a
string level, check the height of the ground at this location. If the measurement remains the
same, set two posts the same distance apart as the two post located at the head of the stairs.
If not either plan on adding a landing at the bottom of the stairs at 46-1/2" or recalculate
the rise and run again keeping in mind there are minimums and maximums to consider. Pickup a
spec sheet from the city or simply review your design with them. The stringers that support
the steps or treads are made from 2x12 pressure treated yellow pine. Select material that has
few knot and no splits. Layout
the first stringer using a framing square. Once you have made your cuts and checked it for
acceptable fit, use it to trace onto the second stringer. Note the 6-1/4" step at the far left,
this is the bottom step, the 1-1/2" difference in height is to allow for the treads, once
they are installed each step will be 7-3/4" tall. If you will be installing riser boards on
each step, the top step (already having a 2x6 riser)
should be cut shorter. For example,
if the remaining risers are 3/4" thick, cut the top step 10-1/4" instead of 11". Now all runs
will be equal in size. It is acceptable to have the treads hang beyond the front of each step
17.) KDAT, this stands for Kiln Dried After Treatment and it is recommended that you use this
type of wood particularly for the surface of a deck. Kiln drying is the process by which
moisture is removed from wood. All wood used for building is dried by one method or another,
such as by air, sun or kiln. Pressure treated wood has been submerged in a chemical
solution and pressurized to force those chemicals deep into the wood fibers. When that happens
of coarse the wood swells. KDAT simply means drying the wood after it has been treated and thereby
removing the excess moisture and the swelling prior to installation. Have you ever noticed a deck
where there were large gaps between the ends and or edges of the boards? This is from using wood
with too high of a moisure content. There are a number of ways to lay the surface...perpendicular
to the joist or at a angle, even at multiple angles to produce a basket weave effect. We will however
lay this surface perpendicular to the joist. For ease of installation I like to start the surface
to the outter edge away from the wall line when I can. That way I can be sure to have the cuts that
fit around the posts in both of the first two rows of surface. You'll get a much better fit
this way than trying to thread the posts through holes in the center of the boards.
Fasten surface with either ring shank or screw shank hot dipped galvanized nails or a better choice
would be screws made specifically for deck installation and also found at most hardware stores.
18.) This example
shows the lower
spindle section of a typical rail system. It can be installed facing in towards the deck surface or
out facing away. After installing this section, install the top rail, in the example a 2x6. Here are
some additional photos
of just such a
rail system, although you'll notice the spacing requirments were not so stringent.