Under-construction inspection: what to look for at each stage

Buying an under-construction property is one of the riskier property transactions in India, and not primarily for the reasons people usually worry about (builder credibility, RERA compliance, delays). The structural risks — the ones that determine whether your investment is actually sound — are visible only at specific stages of construction. Miss those stages, and you miss your chance to catch problems before concrete covers them permanently.

Here's what to inspect at each major construction stage, and why each stage matters differently.

---

Stage 1: Foundation and pre-slab (before the ground floor slab is poured)

This is the most important stage, and the most overlooked.

Once the ground floor slab is poured, you cannot see what's under it. The foundation type, the depth and quality of the footings, the reinforcement steel arrangement — all of this becomes inaccessible. Problems found at this stage can be corrected. Problems found after handover are structural issues you'll live with for decades.

What to check:

Steel reinforcement. The diameter and spacing of rebar in the columns and foundation beams should match what's specified in the structural drawings. Builders sometimes substitute a smaller diameter or space bars wider apart to save material cost. This is a serious structural compromise that will not be visible after the concrete is poured.

Concrete mix quality. Ask for the concrete mix design certificate. For residential construction, M25 is minimum standard. Weaker mixes are used to cut costs and can result in lower compressive strength that only shows up years later.

Column spacing and sizing. Check whether the as-built column layout matches the sanctioned drawings. Unauthorized changes to column positions or sizes during construction are unfortunately common.

Soil compaction. In areas with soft or fill soil — common in newer Gurgaon sectors built on agricultural land — inadequate compaction leads to differential settlement. A geotechnical report should be available for projects in these areas.

---

Stage 2: Superstructure (during floor-by-floor construction)

Each floor as it goes up gives you a window into construction quality that you won't have later.

What to check:

Column concrete quality. Look at exposed columns before they're plastered. Honeycombing (visible voids in the concrete surface), excessive cracks, or discolouration can indicate poor pour quality or premature form removal.

Slab thickness. The minimum thickness for a residential floor slab under Indian Standards is 100mm for lightly loaded spans, but typically 125–150mm is specified for standard residential construction. Thinner slabs have lower structural capacity and worse acoustic performance.

Brick / block quality and laying. For non-structural walls, check that blocks or bricks are properly bonded, joints are uniform, and that walls are plumb. Poor masonry quality leads to cracking after the building settles.

Waterproofing on wet area slabs. The bathrooms, kitchen, and terraces need a waterproofing membrane applied before tiling. This is often skipped or done poorly by cost-cutting builders. Ask specifically — and inspect — whether proper membrane waterproofing has been applied.

---

Stage 3: Finishing and handover

This is the stage most buyers inspect, and for good reason — it's the most visible. But it's also the stage where the critical structural work is already done and hidden. What you can assess at this stage:

What to check:

Plumbing pressure and drainage. Run water in every fitting simultaneously. Pressure under load matters — a well-designed system handles simultaneous use. Check drain flow in every bathroom and kitchen.

Electrical system completeness. Every socket should be tested for proper earthing and polarity. The MCB panel should be correctly labelled and load-balanced. The earthing system should be connected throughout (not just in some rooms).

Wall and floor finish quality. Hollow tiles (tap them — a hollow sound means inadequate adhesion), uneven floor levels (affects drainage and appearance), and visible cracks in plaster are all indicators of finish quality.

Door and window fit. Frames should be perfectly plumb and square. Windows should close watertight. Gaps between frames and walls need to be properly sealed.

Snagging list vs. defect list. There's a difference. A snagging list is cosmetic items that need finishing — paint drips, uneven grouting, fixtures not fully installed. A defect list is functional problems — drain that doesn't drain, socket that doesn't work, door that won't close. Ensure you distinguish between these and get the builder's written commitment to address both before final payment.

---

The honest bottom line on under-construction purchases

The structural integrity of your property is decided in the first two stages. By handover, you're checking finishes and systems, not foundations.

If you're buying under-construction and want a meaningful inspection, you need access at Stage 1 or 2. This requires either purchasing from a builder who allows buyer inspections during construction (some do), or having a clause in your agreement that gives you inspection rights at specific stages.

Many buyers don't know this is possible to negotiate for. It is. If a builder won't allow inspection access during construction, that itself is information.

Suresh K. is Parakh's Lead Inspector with a civil engineering background, 8 years with PWD, and 210+ inspections across Delhi and Gurgaon.