Is scanning the slab enough before coring?
Scanning reduces the risk but does not remove it. Ground-penetrating radar and electromagnetic cover meters can locate reinforcement, tendons and some services, but readings need interpretation, can be confused by congested reinforcement or metal decking, and tell you nothing about design intent. Scanning should be combined with the structural drawings and a PE's decision on where coring is acceptable. Original plans may not match what was actually built, so investigation on site matters.
From the RRD Field Guide, checked against the sources cited in Hacking Walls and Slabs in Singapore: Structural Elements, PT Slabs and Household Shelters. General information, not advice for your project.
The fuller picture
In Singapore you may remove or open a wall without BCA submission only if it is genuinely non-load-bearing, meaning it carries nothing but its own weight. Openings in reinforced concrete walls, beams, columns or most slabs need a PE's structural plans and a BCA permit before work starts. Household and storey shelters must not be hacked; only limited drilling and finishes are allowed under SCDF's rules.
More questions on this topic
- How can I tell whether a wall is structural?
- Do I need BCA approval to hack a non-structural wall?
- Can I core a hole through a floor slab for a pipe?
- Why are post-tensioned slabs so dangerous to core?
- Can I hack or modify my household shelter?
- What happens if structural works are done without a permit?
- Does a condo need to approve hacking inside my unit?