Selective Demolition: What’s Easy to Miss in Selective Demolition and Why It Matters.

Selective demolition isn’t about knocking down walls, it’s about knowing exactly what not to touch. Anyone can swing a hammer. Very few can dismantle a facility from the inside out without disrupting operations, compromising safety, or uncovering expensive surprises halfway through the project.

After more than 30 years working inside hospitals, industrial plants, and contaminated sites, we’ve seen what happens when selective demolition is treated like a “light” version of demolition.

Here are four big blind spots.

1. Hidden Utilities - The Single Biggest Threat Inside an Active Facility

Inside older buildings, especially industrial and institutional facilities, utilities rarely exist where the drawings say they do.

Contractors can assume:

• “If it’s not on the plan, it’s not there.”

• “That conduit is dead.”

• “Those pipes don’t run through this section.”

Reality says otherwise.

What can be hidden:

• Abandoned-but-live electrical conduits

• Steam lines buried in walls or floors

• Process piping routed in undocumented paths

• Data lines and fiber runs installed during mid-life upgrades

• Water supply branches hidden behind chases

• Refrigerant lines for active cooling systems

• Sprinkler feeds and fire alarm cabling

Why it matters:

Hit one, and the project isn’t delayed; it stops.

Worst case:

• Flooding

• Power outages

• Production downtime

• Safety shutoffs

• Hazmat spills

• Insurance claims

• OSHA involvement

  
  

Selective demolition demands something inexperienced contractors don’t know how to do: positively identify every utility, confirm it’s isolated, and protect anything remaining live.

This is where Melching excels because we’ve been burned before, we know what to look for, and we absolutely don’t ever assume.

2. Structural Sequencing - Why Taking Down the Wrong Piece First Can Collapse the Plan…or the Building

Selective demo is often performed in buildings that have:

• Been renovated multiple times

• Had load paths altered

• Been partially decommissioned

• Structural steel hidden behind finishes

• Aging beams or compromised concrete

  
  

Some demo contractors may think: “Interior = non-structural.”

That many not be the case.

Common oversights:

• Cutting a chase or shaft that’s carrying more load than expected

• Removing a wall that’s been converted into a load path

• Weakening a floor by removing too much at once

• Not understanding how mezzanines transfer weight

• Cutting bracing or lateral supports

• Failing to evaluate vibration impacts from equipment removal

  
  

Why this matters:

Even minor selective demo can change the stability of a space.

This is why Melching uses:

• Structural sequencing plans

• Engineering review when necessary

• Controlled dismantling procedures

• Experienced foremen who know how buildings behave in the real world

  
  

3. Contamination Pockets - What You Can’t See Will Cost You

Industrial and medical facilities have layers of history. And with those layers come materials and residues that can’t be identified by sight alone.

Contamination most contractors overlook:

• Lead dust in wall cavities

• Asbestos tucked behind multiple renovations

• Mercury residue from old process equipment

• Oil-soaked slab pockets

• PCBs in caulking, mastics, and old control systems

• Mold in plenum spaces

• Chemical residues near tanks or piping

• Biological waste behind hospital infrastructure

Some contractors may think selective demo is “clean work.”It’s not. It’s often the most hazardous work on the site.

Why it matters:

• Contaminants spread easily during interior demo

• Improper containment leads to shutdowns

• Regulatory fines become real, fast

• Remediation becomes far more expensive if disturbed

Melching approaches selective demo like environmental remediation, because many times, it is.

We identify hotspots early, isolate them, and coordinate with consultants and regulators so the project stays clean, safe, and fully compliant.

4. Ceiling Plenum Dangers - The Most Overlooked and Riskiest Part of Any Interior Demo

The ceiling plenum is the Wild West of building interiors.

It’s where decades of upgrades, patches, reroutes, and additions end up, often with minimal documentation.

What’s hiding up there:

• Abandoned-but-live electrical runs

• Fire alarm loops

• Fiber and data bundles

• HVAC supply and return paths

• Sprinkler piping

• Old mechanical supports

• Loose insulation

• Mold growth

• Hazardous dust accumulation

• Unstable hangers or overhead structures

Risks if contractors don’t know what they’re doing:

• Fire system discharge

• Unplanned outages

• Falls from ceiling failures

• Heat/smoke system damage

• Mold spread

• Shutdown of entire departments or production areas

Melching treats the plenum like a hazardous space:

• Physical verification of all utilities

• Proper isolation

• Negative air and dust control

• Step-by-step dismantling

• Daily coordination with stakeholders

That’s why we can work safely in active hospitals, plants, and high-sensitivity buildings without disruptions.

The Bottom Line

Selective demolition isn’t easy and it’s never “light work.”

It demands:

• Experience

• Precision

• Environmental awareness

• Engineering-level thinking

• Attention to detail

• Understanding how active facilities operate