Can I Continue Construction as per Old Structural Drawings Without NDT Testing?
This is a very common question I receive as a structural engineer:
“My building is hardly 4 years old. Only part construction was done, and work was stopped for the last 3 years. Now I want to restart construction exactly as per the old structural drawings. Is NDT testing really required?”
At first glance, the answer appears obvious to many clients —
“The building is young; nothing should be wrong.”
But structural safety does not work on assumptions. Let us understand this with a simple real-life example.
The Medical Analogy: A Young, Fit Boy
Imagine a 25-year-old boy.
• He looks healthy
• He is fit
• He has no visible illness
• He exercises regularly
Now, without conducting any medical tests — no blood tests, no ECG, no BP check — can even the most experienced physician give a 100% guarantee that everything inside his body is perfectly normal?
The answer is NO.
Why?
Because:
• Many health issues are not visible externally
• Problems may exist internally without symptoms
• Only diagnostic tests can confirm actual health
Now Replace the Boy with Your Building
Your building may be:
• Only 4 years old
• Visually looking sound
• Constructed as per approved drawings
• Left unused and exposed for 3 years
But internally, several things may have changed.
Just like the human body, a building also “ages” when left unattended, and this could affect its structural safety.
What Happens to a Partially Constructed Building Left Idle?
During the 3 years of construction stoppage, the structure may have experienced:
• Carbonation of concrete
• Moisture ingress
• Corrosion initiation in reinforcement
• Honeycombing is becoming active
• Shrinkage cracks widening
• Variation in concrete strength due to improper curing
• Environmental exposure (rain, heat, pollution)
Most of these issues cannot be judged by the naked eye. Therefore, a structural assessment is needed to ensure the building’s integrity.
Why Old Structural Drawings Alone Are Not Enough
Structural drawings are based on assumed material strengths:
• Concrete grade
• Steel strength
• Bond between steel and concrete
But after years of exposure and stoppage:
• Actual concrete strength may differ
• Steel corrosion may have reduced capacity
• Structural members may not behave as originally designed
So, continuing the construction, which is already part construction blindly as per the old drawings, is equivalent to:
Taking medicines without a diagnosis.
What Is NDT Testing and Why Is It Required?
Non-Destructive Testing (NDT) helps assess the actual health of the structure without damaging it.
Common tests include:
• Rebound Hammer Test (surface strength)
• Ultrasonic Pulse Velocity (internal quality)
• Half-cell potential (corrosion probability)
• Cover meter test (reinforcement cover)
These tests help answer critical questions:
• Is the concrete still strong enough?
• Has corrosion started?
• Is the existing structure safe to take future loads?
Concrete strength testing and corrosion in reinforced concrete can be detected through these tests.
Real-World Example from Practice
I have personally seen cases where:
• Buildings looked perfectly fine
• But NDT revealed low concrete strength
• Reinforcement corrosion had already started
• Structural strengthening became necessary before proceeding further
Had part construction continued without testing, the risk of:
• Excessive deflection
• Cracking
• Long-term durability failure
• Even structural distress
would have increased significantly. A structural health monitoring process could have prevented these issues.
Final Verdict: Is NDT Testing Really Required?
Yes. Absolutely.
Not because:
• The building is old
But because:
• The building has remained exposed and incomplete
• Actual material health is unknown
• Structural safety must be verified, not assumed
Just like a doctor relies on tests before certifying health,
A structural engineer relies on NDT results before certifying safety.
Advice to Building Owners
Before restarting part construction:
- Conduct NDT testing
- Get a structural assessment report
- Review old drawings based on test results
- Proceed only after structural confirmation
This small step today can:
• Save huge repair costs tomorrow
• Ensure the safety of occupants
• Increase the life of the building
• Give peace of mind
Remember:
👉 A building may look healthy, but only tests can confirm its fitness. Don’t skip structural safety assessment or concrete strength testing for your building.