BUILDING A DECK?
HERE
ARE SOME DECK BUILDING BASICS
A
deck is basically a floor structure supported on posts. Loads on the deck from
people, furniture, snow, etc. are transferred from the decking, onto joists, to
beams, down posts, to foundations and into the soil below. All of these
components play an important role in the function of the deck and must be sized
and constructed properly to make the deck safe. Because we construct a deck
from the ground up, lets begin at the bottom.
SOIL AND FOUNDATIONS
Deck piers must extend down to frost line
(30") and be large enough in diameter to support 1000 to 3000 pounds
concentrated on them by the posts. The soil must be stiff and water removed
from the holes before placing concrete. Deck posts should never be placed on an
existing patio. Frost heave and the heavy concentrated loads may cause movement
and premature failures.
POSTS
Typically posts are 4X4 lumber, however on
higher decks, many builders will use 4X6 or 6X6 lumber. Posts must be securely
anchored to the foundations or embedded in the concrete.
BEAMS
Because of the flexibility of deck designs,
it is difficult to give a basic rule of thumb for sizing beams. The beam size
is dependent on the beam span, the number of beams proposed and the span of
joists resting on them. Beams rest on top of the posts or are attached to the
posts with bolts.
JOISTS
Joists are spaced at regular intervals; the
most common spacing is 16". The following is a joist span table for sizing
your joists. This can be used for #2 pressure treated SYP
lumber at 16" spacing:
|
JOIST SIZE @ 16" SPACING |
MAXIMUM JOIST SPAN |
|
2x6 |
9 9" |
|
2x8 |
12 10 |
|
2x10 |
161 |
|
2x12 |
1810" |
Many times the joists are connected to the
house by attaching a ledger board with lag bolts into wood or anchors into
concrete. The joists are typically connected to the ledger board using metal
joist hangers.
DECKING
The deck surface is normally constructed of
2X4 or 2X6 lumber or 5/4 X 4 or 5/4 X 6 rounded-edge deck boards butted
together. End joints for the decking should fall over a joist.
Gaurdrails
All decks that are 30" or more above
the ground must have a minimum 36" high guardrail. This guardrail must
have intermediate members that prevent the passage of a 4" ball.
Guardrails typically use closely spaced balusters (thin vertical members) or criss-crossed lattice to meet this requirement.
STAIRS
Stairs must be stable and have 8.25"
maximum risers (vertical dimension of each step) and 9" minimum treads
(the part you step on). If the stair has 3 or more risers it must have a
handrail. Open risers must not permit
passage of a 4 sphere where they are 30 or more above grade
MATERIALS
Decks in our area are typically constructed
of pressure treated lumber. Deck surfacing materials are also available in an
approved composite material. Both of
these types are resistant to rot and decay. Nails, bolts and screws are hot-dipped
galvanized or stainless steel to resist rust.
Please remember that the Springdale