Top 5 Most Common Deck Defects

Gingles Inspections - Branson Home Inspector

Does your deck contain any of these defects?

What deck defects do I typically find at inspections?  A deck is a structure that should be carefully planned, built, and maintained.  Here is a short list of the most common defects I find with decks in the Kansas City area.

5. Damaged, decayed, or broken wood.  Damaged or broken wood at the deck surface, support structure or guard railing is a potential injury hazard.  In most cases, damaged or broken wood can easily be replaced.  Decay noted at wood could indicate a moisture problem may exist, or improper contact of wood and the grade or concrete surface.    Replacement or repair is recommended


Decay at a Grandview, MO deck structure.

4. Improper connections.  When the deck is to be supported to the home, the ledger board of the deck is required to be lag bolted, or bolted using threaded rod, washers, and nuts.  Approximately 90% of all deck collapses occur due to inadequate connection to the home.  Deck joists for the floor structure are supposed to have 1-1/2″ of bearing on wood or metal.  In most cases this requires joist hangers.  Toe-nailing joists is susceptible to withdrawal.   Repairs in accordance with present standards and best practices recommended.

Joist connection failure

Joist connection failure at a home in Raymore, MO

Improper connection

Improper deck connection at a Belton, MO home. Nails were used to fasten the deck to the home.

3. Unsafe staircases.  An often found defect is unsafe staircases or steps.  Stairways should not sway or move when traveled.  Improper landings, inconsistent tread height, non-conforming openings, improper connections are just to name a few.  If your deck has a dangerous staircase, you should seek the help of a professional.

Dangerous staircase

This Pleasant Hill, MO staircase had inconsistent tread height, inadequate support, and was shaky

2. Loose guard railing.  Guard railing that may not withstand 200lbs of force is a potential safety hazard for users of the deck.  Notched 4×4 posts, improper or inadequate post attachment, insufficient amount of posts are typical culprits.  I am like most of you – I like to lean on guard railing and any railing that is weak should be repaired or replaced.

1. DIY builds, under-engineered, not to code.  Creative homeowners who have skill yet lack knowledge of code can create dangerous situations as decks age.  Many new construction decks are not built to building codes or standards.
Common defect in this arena is a bolted beam to posts.  This configuration relies on the shear strength of the fasteners used.  Code requires an 1-½” minimum bearing on wood or steel for beams and joists. Notched posts, undersized joists, uneven planes, trip hazards, fall hazards, etc.  Seek the advice of a professional.

Over-spanned structure.

Over-spanned joists at the deck structure. Look closely at the photo and you will notice a sag in the floor structure.

DIY, not to code, under-engineered.

The beam at this Lee’s Summit, MO deck is bolted to the support posts.

In conclusion, what should you do if your deck has some of these problems?  Have it looked at by a professional.  Below are a few links to some guides for building decks while conforming to code.

American Wood Council – Deck Guide

Simpson Strong Tie – Deck Framing Guide

Johnson County Kansas Deck Construction Guide


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