Deck Check

By Natalie Rodriguez of This Old House magazine

Posted by Action Plus Home Inspections

Our six-point inspection plan will help you spot signs of trouble

According to the North American Deck and Railing Association, there’s been an increase in the number of decks that have collapsed, fallen apart, or otherwise failed. In most cases, simple upkeep could have prevented these incidents, which tend to happen (no surprise) when decks are packed with people. Make such an inspection an annual affair—it takes a few minutes—and fix any problems before inviting the gang over.

For more information on deck safety, check out the North American Deck and Railing Association.

check materials for split or decaying wood


Check for split or decaying wood. Inspect cracks with a flathead screwdriver; if you can insert it more than ¼ inch into any cracks, or if the wood feels spongy or breaks off without splintering, this could indicate rot. Keep an eye out for holes, which could mean insects have burrowed in and made a home.

ledger board

Ledger Board

This weight-bearing board connects the deck to your house. Make sure it’s attached with ½-inch stainless- or galvanized-steel lag screws and through bolts, rather than nails, which can pop out. Check for a widened gap between the house and the ledger, which may signal that the bolts need tightening.

flashing check


Flashing around the ledger board prevents moisture from building up and causing rot. Look to see if it has pulled away from the house, and make sure caulk that seals overlapping pieces is intact. Inspect for mud or debris stuck between the spacer and the exterior wall, a sign the flashing’s been breached.

railings and balusters check

Railings and Balusters

Firmly grasp and wriggle these to make sure they’re secure. Also double-check whether they meet local codes, which generally call for a railing at least 3 feet high with balusters spaced no wider than 4 inches apart. Toenail loose pieces back into place, adding glue for extra security, or replace them entirely.

support post check

Support Posts

Look for loose connections between posts and the deck’s beams. Tighten and replace ½-inch through bolts as needed. Posts should be 6 inches square or larger, and no taller than 14 feet.

surface finish check

Surface Finish

Look for mildew or areas where water doesn’t bead up on contact. If you find any, power-wash the deck with a solution of one part bleach (use only oxygenated bleach for cedar decks), three to five parts water, and laundry soap. Let it dry before applying a new layer of penetrating waterproof finish.

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