The Most Common Unforeseen Issues That Come Up When Building a Deck

As a parent to 3 young boys, one thing I've learned is that things rarely go exactly as planned. I'm learning to be more flexible with my time and expecting the unexpected, rather than fighting to maintain things the way I want them.

This morning, my whole day was thrown some curveballs by my 1 and 3 year olds, and it made me think of how often our deck builds also don't go as planned.

Over the years, we've learned to expect certain "unexpected issues" and account for them in our pre-job planning. While we can't avoid every issue 100% of the time, we've learned to navigate the common ones, and we've gotten really good at flexing on the big ones.

If you're interested in reading about our most difficult deck build to date, click here.

This article outlines what we most often uncover once construction starts — and why these surprises are more common than homeowners realize.

Even with good planning, detailed designs, and experienced builders, deck projects don’t always go exactly as expected. Homes — especially in the Northeast — have history, quirks, and conditions that aren’t always visible until work begins.

For homeowners in Selinsgrove, Shamokin Dam, Sunbury, Northumberland, Lewisburg, and Danville, understanding the most common unforeseen issues helps set realistic expectations and removes a lot of unnecessary stress during a deck build.

1. Hidden Conditions Below Grade

One of the most common unknowns is what’s underground.

Once digging begins, we sometimes encounter:

• Old concrete footings from previous structures

• Buried debris or construction waste

• Large rocks or ledge

• Poor or inconsistent soil conditions

Why this matters:

• Footings must meet depth and bearing requirements

• Unexpected obstructions can require relocation or redesign

• Soil conditions affect footing size and stability

None of this is visible during a site visit — it only reveals itself once excavation begins.

2. Existing Structures Not Built to Current Code

Many decks are attached to:

• Older homes

• Additions

• Rim joists that don’t meet current standards

Common discoveries include:

• Missing or undersized ledger boards

• Improper flashing

• Structural members that were never designed to carry deck loads

When this happens, additional work is often required to ensure the new deck is safe and code-compliant, even if the house itself has stood for decades.

3. Out-of-Square or Out-of-Level Conditions

Very few homes are perfectly square or level — especially older ones.

Once framing begins, we often find:

• Foundation walls that aren’t straight

• House corners that are out of square

• Slopes or elevation changes that weren’t obvious on paper

These conditions require:

• Careful layout adjustments

• Custom framing solutions

• Extra time to ensure clean, finished results

This is normal — but it does require experience and flexibility.

4. Permit or Inspection Clarifications

Even when permits are approved, inspectors may:

• Request clarification on details

• Ask for minor adjustments

• Interpret requirements slightly differently

This is especially common for:

• Footing placement

• Guardrail details

• Stair geometry

• Ledger attachment methods

These aren’t mistakes — they’re part of working within a real-world regulatory environment. Experienced contractors anticipate and handle these conversations smoothly.

5. Material Behavior After Installation

Some issues don’t appear immediately.

Pressure-treated lumber, in particular, may:

• Check or crack as it dries

• Shrink slightly

• Twist or move subtly

Composite and PVC decking can also:

• Expand or contract with temperature

• Highlight framing irregularities if tolerances aren’t tight

These are material realities, not failures — but they require proper installation techniques to manage.

6. Weather-Related Delays or Adjustments

In Central Pennsylvania, weather is always a variable.

Common impacts include:

• Rain delaying concrete pours

• Frozen ground affecting excavation

• Extreme heat or cold impacting materials

Good planning minimizes disruption, but weather can still introduce short pauses or sequencing changes.

7. Discovering Previous DIY or Temporary Work

Occasionally, once demolition begins, we uncover:

• Temporary repairs

• Non-structural additions

• Improvised framing or supports

These conditions often require correction before new work can safely continue — even if they’ve “worked” for years.

Why These Issues Aren’t a Sign of a Bad Project

Unforeseen issues don’t mean:

• Poor planning

• Bad design

• Incompetence

They mean the project is interacting with real conditions, not assumptions.

What matters most is:

• How quickly issues are identified

• How clearly they’re communicated

• How thoughtfully they’re resolved

Why Experience and Process Matter

Seasoned builders expect the unexpected. They:

• Budget time for problem-solving

• Communicate early and clearly

• Adjust plans without compromising safety or quality

• Keep projects moving forward responsibly

This is where discipline and diligence make the biggest difference.

Final Thoughts for Homeowners

Deck projects are an investment, and like most construction, they involve working with existing conditions that aren’t always predictable. Understanding common unforeseen issues helps homeowners approach the process with clarity and confidence.

For homeowners in Selinsgrove, Shamokin Dam, Sunbury, Northumberland, Lewisburg, and Danville, the goal isn’t to avoid every surprise — it’s to work with professionals who know how to handle them well.