How to Inspect Your Deck or Porch

A deck seems simple—just some boards on a frame, right? But that structure is holding people, furniture, and sometimes hot tubs. It’s exposed to sun, rain, snow, and freeze-thaw cycles year after year. Wood rots, fasteners corrode, and connections loosen. The scary part is that a deck can look fine from the surface while failing underneath. Annual inspection catches problems early.

Why This Matters

Deck failures are more common than you might think. When they happen, people get hurt:

• Rot and decay – Weakens structural members invisibly
• Fastener failure – Nails pull out, screws rust through
• Connection failure – Ledger board separates from house
• Rail collapse – Loose railings give way under pressure
• Post failure – Ground contact causes rot at the base

A deck inspection takes thirty minutes and can prevent serious injuries.

The Ledger Board (Most Critical Connection)

The ledger board is the structural member that attaches the deck to your house. It’s the most common point of failure and the most dangerous.

What to Check

1. Connection to house:

   • Lag screws or bolts (not just nails)
   • Proper spacing (typically 16 inches on center)
   • No visible gaps between ledger and house

2. Flashing:

   • Metal flashing should be visible above the ledger
   • Prevents water from running behind the board
   • No missing or damaged sections

3. Signs of rot:

   • Probe along the top edge with your screwdriver
   • Soft wood indicates rot
   • Check at the ends where moisture collects

4. House attachment:

   • Ledger should be attached to the house rim joist (solid wood)
   • Not just to siding or sheathing
   • This is hard to verify, but flashing presence is a good sign

If your deck is attached only with nails or shows rot at the ledger, stop using it and call a professional immediately.

Framing Inspection

The beams, joists, and posts that support the deck surface:

Joists

1. Look along the length of each joist from below
2. Check for sagging, cracking, or twisting
3. Probe with screwdriver at ends and mid-span
4. Look for soft spots indicating rot

Beams

1. Heavy timbers that support joists
2. Check connection points to posts
3. Look for cracking, checking (surface cracks), or rot
4. Verify proper bearing on posts

Posts

1. Vertical supports that carry weight to the ground
2. Check at ground level – This is where rot starts
3. Probe the base of each post with your screwdriver
4. Look for decay, insect damage, or sinking
5. Posts should rest on concrete footings, not buried in dirt

Hardware

1. Joist hangers should be present on all joist ends
2. Nails should be in every hole
3. Look for rusted or corroded hardware
4. Check for missing fasteners

Deck Boards and Surface

Individual Boards

1. Walk the deck and feel for soft spots or bounce
2. Look for boards that move underfoot
3. Check for cracking, splitting, or warping
4. Probe suspicious areas with screwdriver

Fasteners

1. Popped nails (sticking up)
2. Rusted screws
3. Missing fasteners
4. Screws that spin freely (stripped holes)

Gaps and Drainage

1. Gaps between boards should allow water drainage
2. Debris buildup traps moisture against wood
3. Sweep clean during inspection

Railings and Stairs

Railings

1. Grab each post and shake firmly
2. No movement should occur
3. Check where posts connect to the deck frame
4. Balusters (vertical pieces) shouldn’t be loose or missing
5. Rails should be at proper height (typically 36-42 inches)

Stair Stringers

1. The saw-toothed boards that support steps
2. Check for cracks at the cut angles
3. Look for rot at ground contact
4. Verify solid attachment to the deck

Stair Treads

1. Should be solid underfoot
2. Check for rot, splitting, or excessive wear
3. Verify secure fastening

Post-to-Ground Connection

This is a common failure point:

1. Posts should be attached to concrete footings above grade
2. Posts buried directly in soil will rot
3. Posts in concrete that holds water will rot
4. Look for rot at the post base with your screwdriver

Warning Signs of Serious Problems

• Deck feels bouncy or spongy when walked on
• Visible sagging or tilting
• Large cracks in structural members
• Soft wood when probed
• Railings that move when pushed
• Gap between deck and house (ledger separation)
• Rust-stained wood around fasteners
• Fungal growth or insect damage

If you see any of these, restrict access and call a professional.

DIY vs. Call a Pro

DIY: Annual inspection, minor repairs (board replacement, tightening fasteners), cleaning and sealing.

Call a pro: Ledger board issues, structural rot, post replacement, railing reconstruction, or any work beyond your skill and comfort level. Find a contractor →

How Often to Inspect

• Full inspection: Once a year (spring recommended)
• After harsh winters: Check for snow/ice damage
• Before heavy use: If hosting events on the deck
• If you notice movement or softness: Immediately

The Bottom Line

Decks don’t last forever, and they don’t fail slowly. They fail suddenly when the cumulative damage reaches a tipping point. Thirty minutes of inspection once a year catches problems while they’re fixable. The ledger board, posts, and railings deserve your closest attention—they’re the difference between a safe deck and a collapse.