Recommended Construction Sequence for Basement in RCC Buildings – Columns vs Retaining Walls First and Impact on Curing and strength

[ananthp]

I am currently constructing a residential building where am raising basement from NG level and would like clarification on the correct construction sequence for the basement level in an RCC framed structure. I haven't started construction yet but hinting for good contractor

Some contractors have suggested that for the basement portion, the retaining wall (brick/block masonry) should be constructed first after excavation and PCC, and then the RCC columns should be cast later. Their reasoning is that building the wall first helps with soil consolidation and stability after backfilling.

However, my understanding was that the typical structural sequence is to cast RCC columns first (from footing/pedestal) and then construct masonry or retaining walls as infill.

I also have a concern regarding the curing and bond quality if masonry is constructed first. If the wall is built before the column, it will likely cover three sides of the column location, leaving only one face accessible. When the column concrete is poured later:

• Proper curing of the column surfaces on the three enclosed sides may not be possible.
• The brick/block masonry and mortar may absorb moisture from the fresh concrete, potentially affecting hydration and strength in those areas.
• It may also create difficulties in compaction, alignment, and proper formwork.

Given this, I would like to understand from experienced structural engineers:

1. What is the recommended construction sequence for basement levels in RCC framed buildings — columns first or retaining walls first? for this qork alone most of the builders are construction the wall first and then column later
2. Is constructing masonry/retaining walls before columns ever recommended, and under what conditions?
3. Could this approach negatively impact curing, bonding, or structural performance of the column?

The project is a residential RCC framed building with a stilt level and stilt will be 3 feet from NG level, and I want to ensure the construction follows sound structural engineering practices.

Any guidance or references to standard practices would be greatly appreciated.

reference image is below, this is from YT but most contractors follow this practice

 

[ferrer.vicente1997@gmail.]

Your understanding is correct — the standard sequence for RCC framed structures is columns first, then masonry infill. Building the retaining wall before columns creates exactly the problems you've identified.

The curing issue is the most critical: when three sides of a column are enclosed by masonry, you cannot properly wet-cure the concrete on those faces. IS 456:2000 Clause 13.5 requires maintaining concrete in a moist condition for minimum 7 days (14 days for blended cement). The brick/block masonry will continuously absorb moisture from the fresh concrete, accelerating surface drying and reducing hydration — this directly impacts compressive strength development in the enclosed zone.

The second issue is workability and compaction. Casting a column into a pre-built masonry pocket limits vibrator access and makes achieving proper consolidation nearly impossible, especially at the base where honeycombing is most likely. You'll also have difficulty ensuring vertical alignment and plumb over the height.

Why contractors suggest this sequence: it appears faster because they can immediately backfill and work on upper levels while waiting for column concrete to cure. But this trades structural integrity for schedule compression — not an acceptable engineering compromise.

Correct sequence for basement in RCC frame:
1. Excavation + PCC + footing/pedestal
2. Cast RCC columns from pedestal to full basement height
3. Cure columns properly (minimum 7 days wet curing, all four faces accessible)
4. Construct retaining wall as infill between columns
5. Backfill after wall construction

For basement retaining walls specifically: if the design requires the masonry to act as the retaining element (bearing lateral earth pressure), it should be designed and detailed accordingly with proper waterproofing on the external face before backfilling. Most residential basements use the RCC frame to resist lateral loads, with masonry as weather protection only.

The practice you're seeing is common in residential work in India but that doesn't make it correct. IS 456 and SP 34 both assume the standard frame sequence — columns, then infill. Stick with that.

I write about construction materials and site practices in India at builtbychemistry.com?utm_source=forum&utm_medium=comment&utm_campaign=civil4m — working in Rajasthan, I see this exact sequencing mistake frequently.