Terrace Waterproofing Guide

For New RCC Slab | To Be Done after minimum 28 Days Curing

This is a practical step-by-step guide.
Follow sequence properly. Waterproofing fails mainly when steps are skipped or done casually.

Step 1: Surface Preparation

Start only after slab has cured for minimum 28 days.

• Clean surface using wire brush or grinder
• Remove all loose material and dust
• Use blower or dry brush for final cleaning
• Wash surface with water
• While washing, identify and mark cracks

Surface should be clean, solid, and dust-free. Yeh step lightly mat lena, yahin se kaam decide hota hai.

Step 2: Crack Repair

Do not apply coating directly over cracks.

• Open cracks using grinder to about 8 to 10 mm width
• Clean inside the crack properly
• Fill cracks using Epoxy system (Part A Resin 2 parts + Part B Hardener 1 part)

Mixing:

• Mix Part A and Part B as per suggested ratio only
• Do not change ratio
• Can mix sand to make mortar consistency that goes in and fill deeper cracks

Ensure cracks are fully filled and sealed

Step 3: Gola / Cove at Wall Junction

Leakage mostly happens at wall and slab joint.
So gola is compulsory.

• Ensure wall plaster is completed and cured
• Apply a bond coat of epoxy (BS Epoxy 611) at the junction

Gola Mix:

• Cement : Sand : Aggregate (5 mm) = 1 : 1.5 : 3
• Add bonding agent = 4% of cement weight

Example:
If cement = 50 kg, bonding agent = 2 kg

• Form a 75 mm curved gola at the junction

Curing:

• Cure for 3 days
• Keep surface wet using water or wet cloth

Step 4: Waterproofing System

Before starting, check again:
Surface clean hai? Dust free hai? Then only proceed.

Step 4.1 Primer Application

Primer improves bonding between slab and coating.

• Use water-based epoxy primer

Mixing:

• Resin : Hardener : Water = 1 : 2 : 3 (BS SmartPrime WB EP or Similar)

Example:

• 1 litre resin
• 2 litre hardener
• 3 litre water
• Mix properly and apply with brush

👉 Wait 7 to 8 hours before next step

Step 4.2 Waterproofing Coating

Use acrylic cementitious waterproofing system.

First Coat:

• Mix liquid chemical and cement = 1 : 1

Example:

• 1 kg liquid + 1 kg cement
• Apply evenly on surface

👉 Immediately lay glass fiber mesh on wet coat

• Overlap mesh by at least 5 cm
• Press properly so it sits flat

Second and Third Coat:

• After 4 to 6 hours, apply next coats

Mixing:

• Liquid : Cement = 1 : 1.5

Example:

• 1 kg liquid + 1.5 kg cement
• Apply total 2 coats on the insalled fabric layer wth a gap of 4-5 hours each
• Take care that application is not done in high summer heat above 35 degrees celsius. Apply early morning 6 am or after 6 pm in the month of April - August

Wall Treatment:

• Take coating minimum 300 mm height on walls above terrace level

Step 5: Curing and Testing

• After final coat, wait 6 hours
• Start curing

Curing:

• Minimum 3 days
• Use wet cloth or light water spray

Pond Test (Final Check)

• Fill terrace with about 50 mm water
• Keep for 3 to 4 days

Check ceiling below , No leakage means system is working

Step 6: Protection Plaster

Do not leave waterproofing exposed.

Mix:

• Cement : Sand = 1 : 4
• Add bonding agent = 1.5% of cement weight
• Add fiber (6 mm) for crack control

Thickness:

• 8 to 10 mm plaster

This layer protects waterproofing from damage during use or tile work

Final Understanding

Waterproofing is not just applying a chemical.
It is a complete system:

• Surface preparation
• Crack repair
• Gola formation
• Coating application
• Curing
• Protection

If one step is weak, problem will come back.

One Line Summary

Good waterproofing ka matlab hai proper process follow karna, shortcut nahi lena.