As a
home inspector, I must report that the majority of decks that I evaluate
are built with substandard materials and workmanship that endanger the safety
of the occupants. I urge you to take
a few moments and examine the safety of a few key checkpoints that could ultimately
cause injury or death if not corrected. Let's inspect the deck together from top
to bottom.
First,
walk across the deck and take note of any springiness in the floor frame or
do a little bounce at the center point. Did you know that a springy floor frame is
a telltale sign of a problem? The floor frame should be capable of supporting
live and dead loads without exhibiting movement. If the deck does shake,
rattle or roll, then the floor frame is most likely undersized, over-spanned or both.
Reinforcement is needed to prevent collapse.
While on
the deck, walk to the center of the outside guardrail. Holding the railing
with hands spread wide and feet spread wide apart, shift your weight left and
right while pulling on the railing with the objective of trying to make the
deck move
from side to side. If the deck exhibits lateral movement, it is unsafe and reinforcement
is needed to prevent collapse. Elevated decks are notorious for dangerous
swaying problems.
Let's
take a moment to examine the guard railing. Measure the height of the railing
- it should be a minimum of 36 inches high. Take a look at the balusters, they
should be vertical (not horizontal) and the spacing should not exceed a maximum
of 4 inches. Low railings, large spacing between balusters or horizontal balusters
can all result in a personal injury and are unsafe. Grasp some of the balusters
and give them a little twist test to check for secure attachment. The balusters
are best fastened with exterior screws. Shake the railing and posts, there should
be no sign of movement. The posts that support the railings are best fastened
with carriage bolts that run through the post and rim joists. Did you know that the
railing should be capable of withstanding 200 lbs. of lateral pressure? Even treated lumber requires maintenance or
sun damage and decay may result.
Most of the decks I inspect have never received a treatment with wood preservative
and obvious nail pops and splinters stick up from the floor boards and railings
posing a risk of personal injury. Have you ever had to restrain your child while the
doctor struggles to remove nasty splinters from hands or feet? You should
examine all deck surfaces and replace those boards that have splinters or
decay. Sanding away splinters is not an option, as the grain will continue to
lift. Nail
pops should be countersunk. Last, get out there and apply a wood preservative
at 2-3 year intervals.
Take a look up in the air. If a new deck has
been added and it is located beneath
the overhead electrical wires, there could be a serious risk of shock or electrocution.
A ten-foot clearance is needed. Many do-it-yourselfers never consider
the proximity to the electrical service. Shocking!
Take a walk down the deck stairs. Are the
tread & riser dimensions uniform?
Are the handrails and posts secure? Is a center stringer missing resulting in
springy stairs? Are the bases of the stringers buried in the soil or do they
rest upon a
nice little concrete stoop? Next, take a look underneath the stairs as many that I
inspect a weakly attached to the deck as an afterthought just waiting to collapse. Time to get underneath and take a look at
things. One of the most flagrant problems
that I find when inspecting decks is the omission of lag bolts. Check where
the ledger joist or deck is fastened to the house. If you see only nail heads,
then the
installer failed to properly secure the deck frame to the house frame and the
entire structure could collapse during that graduation party. You should see the presence
of "lag bolts" spaced several feet apart that firmly tie the two
structures together.
Without the lag bolts, the shear strength of the nails alone may fail under load
resulting in total deck collapse! Next, take a look at each end of the floor
joists. You should see the presence of metal joist hangers beneath each end of
each joist. If the hangers are missing, then the
floor joists are only end nailed and could collapse under load. The joist hangers
provide each joist with 1 1/2 inches of required end bearing to safely support
all of your guests. If the joist hangers are present, inspect the nail holes in the
hangers themselves to see that each is filled with a joist hanger nail (not a roofing
nail).
If a main girder is present, it should be
properly assembled so that any splices
fall above support posts and with support posts that are properly sized and spaced.
If you note any evidence of sagging or scissoring at joints then there could be a
problem. If the floor joists are cantilevered beyond a main girder, then as a "rule
of thumb" the cantilever should not exceed approximately two feet. I hope that you notice some support posts
beneath the deck and that they are spaced
about 4-7 feet apart. Examine the joint and the method of fastening where the
posts join the floor frame. Often posts are over-notched, decayed or poorly secured
at this location. Next, probe the base of each post for decay at they are exposed
to constant wet dry cycles. Better builders will raise the base of the posts up
on metal anchors to prevent decay and also to secure the posts to the footings. Sight
down the row of support posts and footings for plumb. If you see any signs of
tilting, then a problems is indicated and repair is needed. Down at ground level, there should not be any
vegetation left under the deck and the
footings should extend below frost level (four feet deep in this area). If you find
that the deck posts only rest on concrete blocks or patio blocks then it is obvious
that proper construction standards were not followed and the deck is vulnerable
to frost movement. If you find that the deck posts are buried within the concrete
footings, then the footings will eventually crack from water infiltration and
frost expansion. Ideally, the footings should be four feet in the ground and should
project slightly above grade.
In closing, your deck is part of the means of
egress for the occupants and another
living space. It must be safely built, safely supported and safely fastened to the
home. Any deficiencies in the above could result in collapse and personal injury.
If you have questions about the safety of your deck, then you should consult
a member of the American Society of Home Inspectors or your local building
department.
Information herein was borrowed from ASHI
