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Top 10 Mistakes of Deck Building

Between 2000 and 2008, there were at least 30 reported deaths from deck collapse.  More than 75 percent of people on a collapsing deck were injured. Most collapses occur on decks that are more than 20 years of age or older.  With over 40 million decks in the United States it is important that you check the safety of your deck.  Here is a link to a deck safety checklist.

Mosby Home Consultants inspect several problem decks a month, and these are the 10 most common mistakes they see:

10. Unsealed wood
Unsealed wood decks can age and deteriorate faster than sealed decks.  Proper sealing prolongs the appearance and life of a deck well beyond unsealed decks.  Avoid the “worn out” look by sealing it.

9. Stairs with open risers or missing railings
Open space between steps invites accidents.  Avoid injuries and create a tailored look by covering the risers.  Hand railings are fundamental to the safety of a stairwell.

8. Improper railing height and baluster spacing
Building codes have very specific measurements for railings and balusters to avoid accidents and injuries.

7. Undersized structural members
An undersized structural member increases the risk of deck collapse and can create sagging and improper weight distribution.  Avoid deck warping and collapsing by properly sizing all members and components of your deck.

6. Missing or improper joist hangers
Nails alone are not enough to counteract the shear forces on a structural member.  Joist hangers are an essential element in creating reinforced connections and supported decking. Ensure the safety of your deck by using properly sized, engineered, and correctly installed joist hangers.

5. Improper Deck Materials
Weather resistant materials are necessary on exterior structures to prevent rot or deterioration.  There are specific fasteners for exterior conditions and it is critical that the proper fasteners are used.   Select materials that are expressly made to withstand all weather conditions.

4. Undersized footings
Footings create a solid base for the posts of your deck.  Undersized footings can lead to sagging, warping or collapse.

3. Improper attachment to structure of house (incorrect fasteners)
How your deck attaches to your home determines its safety and durability. This is an area that you may want to overbuild beyond the minimum standards or requirements.   Again material, size, and quality are critical.

2. Improper or missing flashing
Every deck must address water management.  Water can soak into your home at the point where the deck connects to the house.  Properly installed flashing will prevent erosion to the structural integrity of your deck and home.

1. Not obtaining a permit to build a deck
Obtaining a permit is the most overlooked step in deck building.  Safety is the main focus of following the permitting process of your town.

The majority of deck building mistakes can be avoided by applying for a building permit through your City Hall. The permit process requires drawings and specifications of the proposed deck.  Building Inspectors will verify that the deck plans meet the local building and safety codes. This crucial step will save you from making costly mistakes before the first hammer swings.  The permit process requires on-site inspections during construction phases to insure the deck is being built according to code.

It is crucial for the safety of your family and your guests that a deck is built properly.  Learn more about Mosby Building Art’s deck services here. For deck inspection, design, construction, or repairs call the Mosby office at 314.909.1800 or contact them here.

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  • deck building

    Make sure to follow these deck building tips in order to avoid what happened here

  • Deck Revive

    Thanks for sharing this wonderful Blog! After knowing these mistakes, it would be easier to avoid them while creating decks. Every process should have a proper planning. So make sure to pre plan the deck structure and its advantages. Analyze all the aspects of manufacturing of deck whether your planning will succeed or not.

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  • Frankie Little

    I suggest to choose expert deck builders who can assist you in imagining, designing, and creating the deck you’ve always wanted.

  • Frankie Little

    Thanks for sharing this article. Here are some great deck building tips from the experts for first time deck builders.

  • I recently built a dock/deck combination and a laser level came in very handy to get the height of the piers and posts correct across the water and land, saving me a ton of time getting things level. I picked a reasonably priced one… no need for something contractor grade.

  • Nick Overby

    Great article! So many people do not know the proper way to build a deck. It is very important to use these methods in your deck build. Improper deck building can lead to a very dangerous structure.


  • Super helpful tips! I completely agree with #1 on people forgetting to get a permit. It’s easy to think that they aren’t necessary but you don’t want to get caught without it. I built a deck this past summer and almost forgot. I found some helpful tips on how to use my laser level for the deck project at

  • Nathan

    Imus Cap is a joist cap that will seal the top of joists and beams from moisture.