home deck inspection

10-Point Deck Inspection Checklist

David Sherwood Sherwood Inspection Services, LLC 1 Comment

As a homeowner, it is important to ensure your deck is safe to prevent risks to your family and loved ones. No one wants to have a tragedy occur during a backyard barbecue, but an unsafe deck will pose that risk.

There are a number of components of a deck that need to be maintained to ensure deck safety. We discuss how to inspect these components in our deck inspection checklist so you’ll be covered.

home deck

Deck fact: The stairs leading up to a deck are often one of the most overlooked areas and pose one of the largest risks. Our company has inspected thousands of homes with decks and approximately 80% of deck stairs that we’ve inspected are not installed or maintained properly.

Deck Inspection Checklist for Homeowners

The following is a deck inspection checklist you can use to keep your deck safe. This checklist includes 10 areas you should check to ensure that your deck is in good shape:

  1. Base Support
  2. Soil Under the Deck
  3. Structural Support
  4. Flashing Details and Fasteners
  5. Attachments
  6. Framing Brackets
  7. Decking
  8. Wood Condition
  9. Stairs and Steps
  10. Deck Railings

  1. Base Support (Footings & Columns)

    • Footings are usually made of concrete. Poured concrete is typically best and should be installed in the ground below the frost line (or at least 30” into soil and min. 6” round). Check local jurisdiction requirements
    • Keep gutter leaders and water drainage away from footings to prevent erosion and possible movement of footings
    • Columns should have full barring on the concrete footing
    • Wood should not be in direct contact with the concrete as it can cause rot to a main support.
    • Check for rot, movement, and splitting of the column
    • Check the base plate, top plates, brackets, bolts, and fasteners for rust, rot or missing parts and replace as needed
  2. Soil Under the Deck

    • Soil under the deck is mostly forgotten and can cause insect and moisture damage to the deck if not maintained properly
    • Should slope out and away from the house and deck
    • Should be free of any plant growth and weeds
    • Cover soil with plastic or landscapers burlap and cover that with gravel/stone (not mulch)
    • Soil should not come in contact with the wood
  3. Structural Support

    • Structural supports are the framing members or wood boards under the deck flooring that support the deck
    • Check the wood for rot and insect infestation that would look like damage to the wood. This can be from termites, carpenter ants and carpenter bees
    • Look at the wood for severe warping or twisting that pushes the wood out from the board it attaches to, especially at the inner and outer rim joist
    • Check the outside board, called the rim joist, to assure it is secure to the floor or deck joists.
      • Look to make sure the joist hangers and nails are secured
    • Look for sagging that may indicate improper support or sizing of the floor joists. (Local requirements can help assure sizing depending on length)
  4. Flashing Details and Fasteners

    • Flashing is a sheet metal typically used where the house meets the interior joist or header
    • Fasteners include nails, screws, and bolts
    • The flashing cannot always be visible. Check on the interior for water stains
    • Check the exterior for rot to the flashing along the header where it is attached to the house
    • Look for water stains below the flashing or header that may get behind the flashing
    • There may be rot to the header if water is getting trapped between the header and flashing.
      • Be sure to look in this area for water, debris, and rot
    • There was a time period where galvanized fasteners reacted with the pressure treated wood and could rot in just a few years.
      • Check all fasteners for rust/rot and replace as needed
  5. Attachments

    • Attachments: The areas where the deck attaches to something such as the house, typically with bolts
    • Securing the deck to the house needs to be done with through bolts
      • Nails and lag screws are not enough
      • Check to be sure bolts are installed in the header against the house
    • Check the outside header to assure it is properly fastened using joist hangers to the joists, and plates to supports
    • Assess the header that is attached to a pool or hot tub supports to assure they are fastened properly
  6. Framing Brackets

    • Framing brackets include joist hangers, “T” brackets, “L” brackets, span braces, etc.
      • Any metal plate or hanger to secure wood together
    • Check to assure there are proper sized nails in every round hole of the bracket (roofing nails are not acceptable)
    • Make sure the nails are compatible with the brackets to avoid rot
    • Check for rot, white stains, and rust that weaken the brackets
    • Brackets should not be cut, bent, or altered from manufacture installation guidelines
  7. Decking

    • Decking: the boards, either wood or manufactured material, that lays flat on the surface of the deck in which you walk on
    • For synthetic/manufactured material, check for bows/sags to the boards where the floor joist span too far
    • Check to assure they are properly fastened
    • For wood, check for nails popping up where people can injure their feet
    • Check for wood lifting, splitting, and rotting (replace as needed)
  8. Wood condition

    • Wood should not be painted as it will peel and can hold in moisture, use stain or sealant
    • Check for the condition of all wood, framing, decking, rails, supports for warping, bowing, splitting, and rot
    • If wood ends are exposed, they should be sealed to prevent water from getting in that will weaken the wood
    • All warped or bowed supports should be replaced if the deck is higher than 6 feet from the ground
    • Check the support columns if the deck is 10 feet or higher from the ground
      • Assure that the columns are a minimum 6” X 6”
  9. Stairs and steps

    • Wood stairs and steps are vulnerable and dangerous areas if not properly installed and maintained.
    • Stairs and steps are typically made up of treads, the part you step on and stringers that support the treads.
      • Steps are 3 treads or less and stairs are 4 treads or more
    • Check for spits, breakage, and rot to the stingers
    • Look out for loose, bowed, and cracked treads
    • Check all the fasteners and brackets for rot, rust or deterioration
    • Examine where the stringer attaches to the deck and assure it has not pulled loose and is properly secured
  10. Deck Railings

    • The railing on a deck stairway is a very important component. However, simply having a railing does not completely mitigate the risk of falling.
    • Railings are not always required for all decks depending on height. Typically, 30” or taller but check with your jurisdiction
      • If tall enough, railings should be of proper height, typically 36” (Check with your local jurisdiction)
    • Railings should be made of wood or metal. Vinyl is not strong enough. They can be wood with vinyl clad (vinyl over wood)
    • In order to best utilize your deck railing, it is important to make sure that the railing is graspable.
    • A person should be able to grip the rail with their thumb on one side, while still being able to wrap their fingers around the other side.
    • The standard acceptable dimension on a circular railing is between 1-1/4 and 2” in diameter.
    • Assure the rails have proper spacing between the balusters/spindles
      • Typically 4” or less (check with your jurisdiction)
    • Ensure that the deck railing is attached in a stable manner to the deck structure and does not come loose upon having reasonable pressure applied
    • Railings should be secured enough to apply 200lbs of load or pressure against it and not fail
      • Make sure they cannot be moved by the normal weight of an adult

How to test your deck railing:

  • Take a person who’s around 180 lbs and have them push against the rail. You should see very little to no movement. If your deck feels unstable, you should take the following steps:
  • First step is to check the post fasteners. Typically, these are carriage bolts and they should be properly tightened. The posts should be no more than 8 feet apart depending on the sizing of railing. If they are adding more may be needed (For sizing the bolts, see the Simpson Strong Ties sizing chart for deck fasteners).
  • Next, check the balusters. They help to solidify the rail in between the posts so they should not be loose, cracked or broken. Keep in mind that the balusters should be no more than 4” apart and have no opening at the bottom for child safety. If there is an opening at the bottom, you should add some blocking to help prevent a baby or small kid from crawling through the opening.
  • Then, check the top and bottom band joist for loose areas and decay. Repair or replace as needed to assure the balusters and posts have a solid base. Remember that a railing is a system and it is only as strong as each of the components secured together.
  • Lastly, check the rail top for loose areas, slivers, and decay and repair as needed.

The items above are the most common problems we see with decks, but it is in no way meant to be an exhaustible list of potential safety hazards. It’s always best to have your deck periodically evaluated by a qualified contractor to ensure the highest level of safety for yourself and those who use your deck.

We hope our deck inspection checklist will help you to safely enjoy one of the best places to relax – your home’s deck! If you would prefer a professional inspector to do the evaluation for your deck, you can contact us at (860) 646-9983 to request a deck inspection from experts.

For more information from the authority on deck safety, you can refer to NADRA’s Deck Evaluation Guide.

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