Openai/695c9a37-3a18-8002-8a26-b114d6f5d844

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gpt-5-2

User: Action to take to repair the fallen cement in the ceiling

Action to take to repair the fallen cement in the ceiling

Assistant: From the photo, this is spalled plaster / concrete cover on the ceiling.

From the photo, this is spalled plaster / concrete cover on the ceiling. The dark areas are very likely exposed steel (rebar) or old patching compound, which means moisture has reached the ceiling before and caused the cement to lose adhesion.

Below is the correct and durable repair sequence (not just cosmetic):

⚠️ First – Safety

• Wear safety goggles & mask
• Lay plastic sheet (chips will fall)
• If this is a bathroom or under roof slab, avoid using the area during repair

✅ Step-by-Step Repair Method (Recommended)

1. Remove all loose material (VERY IMPORTANT)

• Use a scraper / chisel
• Knock until you reach solid, hard concrete
• Do not patch over weak cement (it will fall again)

👉 If you hear hollow sound, keep removing.

2. Treat exposed steel (if visible)

If you see dark metal or rust stains:

1. Wire-brush the steel until clean
2. Apply anti-rust / rebar primer - Examples (Malaysia): - Sika Rustoff / Sika MonoTop Rebar - Fosroc Nitoprime Zincrich

⏱ Let dry as per product instruction

3. Apply bonding agent

This ensures new mortar sticks permanently.

• Brush on: - Sika Latex - Fosroc Nitobond - Cement + latex mix (DIY option)

⚠️ Do not skip this step.

4. Rebuild with repair mortar

Use polymer-modified repair mortar, not normal cement.

✅ Good options:

• Sika MonoTop 615 / 620
• Fosroc Renderoc HB
• Mapei Planitop

Apply in layers if deep. Press firmly to avoid air pockets.

⏱ Allow curing (usually 24–48 hrs)

5. Skim coat for smooth finish

• Use skim coat / wall putty
• Feather edges so repair blends with ceiling

6. Seal & paint

1. Apply alkali-resistant sealer - Nippon 5170 - Dulux Alkali Resisting Primer
2. Paint with ceiling paint (2 coats)

🚫 What NOT to do

❌ Do not use filler only ❌ Do not paint without repairing rust ❌ Do not patch over loose cement ❌ Do not use silicone or sealant alone

🧐 Important Question (Cause)

To prevent repeat failure, check:

• Is this below a bathroom / balcony / roof?
• Any past water leakage or waterproofing issue?

If you want, tell me:

1. Which room is above this ceiling
2. House age
3. Whether water leaks happened before

I can then recommend waterproofing or preventive steps so this doesn’t happen again.