Roof Casting (Dhalai) Checklist: 10 Things to Check Before Casting Day
In the Northeast a Roof Casting or Dhalai is more than just another phase in the building process – it’s a big deal. It’s a moment your whole family comes together, a small ceremony is performed and the guys who’ve been slaving away on this project get to enjoy a well-deserved meal . After months of elbow grease your house is finally going to get its roof.
But Dhalai is also the one critical moment of truth for your house. The roof slab has to be able to handle the weight of the building above, keep the rain out for years to come and – importantly – give your home a fighting chance in an earthquake. The moment that concrete is released into the air, tho, mistakes are a costly nightmare to try and fix.
Which is why the run-up to casting is just as important as the day itself. Use this roof casting checklist to ensure that everything is good to go before the first load of concrete is even being lifted into place.
Before Casting Day: The 10-Point Checklist
1. Get That Engineer’s Stamps Of Approval
Before you do a single thing, your structural engineer or site supervisor needs to give the shuttering and reinforcement a once over and confirm it all matches the structural drawings. Don’t be tempted to just “get on with it” and skip this step – it’s better to wait a day and get it right than to risk having to redo the whole thing.
- ☐ Structural drawings readily available on site and easily accessible to everyone
- ☐ The engineer/supervisor has personally inspected and given the all clear
2. Give the Shuttering a Thorough Check
The shuttering is like a mould: it holds the wet concrete in place until its set. If the shuttering is weak or uneven, you can expect all sorts of problems – sagging, leaks and even collapse.
- ☐ Is the shuttering level and at the right height, or does it need some tweaking?
- ☐ Are the plates and planks good solid stuff, clean and properly joined, or are they a bit dodgy?
- ☐ Are the gaps between the plates sealed up tight, so no cement slurry starts leaking out?
- ☐ Have you applied some shuttering oil to make the job of getting everything out afterwards a little easier?
3. Make Sure the Props Are Up to the Job
The props have to carry the weight of all that wet concrete, plus the workers and equipment. So, you want to make sure you’ve got them right.
- ☐ Are the props vertical, evenly spaced and firmly in place, not wobbling around?
- ☐ Are they resting on solid ground or planks, not on some loose soil that’s going to give way under the weight?
- ☐ Is the bracing in good order, so the props don’t start shifting about once the concrete is poured?
- ☐ Have you got any broken or bent props sorted out and replaced with new ones?
4. Check the Steel Reinforcement
The steel is the backbone of the slab, and in areas prone to earthquakes like Assam, you really need to get it right.
- ☐ Do you have the bar sizes and spacing spot on, just like the drawings said?
- ☐ Is the steel clean and free of any loose rust, oil or mud?
- ☐ Are the bars all nicely tied up with binding wire, so they can do their job properly?
5. Get the Cover Blocks and Chairs Sorted
Cover blocks keep the steel at the right distance from the shuttering, so the concrete can fully cover it and protect it from rust. Chairs hold the top steel in place, so it doesn’t start wobbling around.
- ☐ Have you got the right thickness of cover blocks in place under the bottom steel?
- ☐ Are the chairs in the right place to support the top bars?
- ☐ Does the steel have any chance of coming into contact with the shuttering?
6. Finish Up the Electrical and Plumbing Work
You really don’t want to have to break up the concrete to add conduits and pipes – much easier to get it all sorted before the concrete sets.
- ☐ Have you got the electrical conduits and fan boxes in place and securely fixed?
- ☐ Are the plumbing sleeves and openings for pipes all sorted, and properly marked and boxed?
- ☐ Are all the conduits properly tied up, so they don’t shift about during the pour?
7. Arrange all materials in advance
Running out of material mid-pour is one of the worst things that can happen on Dhalai day. It creates cold joints, weak lines in the slab where fresh concrete meets hardened concrete.
- ☐ Cement quantity calculated, with a few extra bags in reserve
- ☐ Fresh, lump-free cement with a recent manufacturing date
- ☐ Clean, silt-free sand and properly graded aggregate
- ☐ Enough clean water for mixing and curing
- ☐ Cement stored dry, off the ground and covered
8. Check equipment and backup
- ☐ Concrete mixer serviced and working
- ☐ Needle vibrator available and working, with a spare if possible
- ☐ Generator or backup power arranged
- ☐ Lighting arranged in case work runs late
- ☐ Buckets, pans, trowels and tools ready
9. Plan the team and the pour
Roof casting must be done continuously, from start to finish, without long breaks.
- ☐ Enough masons and labour booked for the full day
- ☐ Clear roles: mixing, carrying, pouring, vibrating, finishing
- ☐ Pouring sequence planned with your mason
- ☐ Slope for drainage planned for the roof surface
10. Check the weather and plan curing
- ☐ Weather forecast checked; avoid casting if heavy rain is expected
- ☐ Polythene sheets ready to protect fresh concrete from sudden rain
- ☐ Curing plan ready: water source, wet hessian or ponding
- ☐ Someone responsible for curing every day
On Casting Day: Do’s and Don’ts
Do This:
- Try to get started early in the day, that way the work will wrap up before the sun goes down
- Use the mix ratio that your engineer has specified, I mean that one is there for a reason
- Compact the concrete with a proper vibrator to really get rid of those air pockets
- Pour that stuff continuously, starting from one end so it all sets properly
- Keep an eye on those steel and cover blocks, make sure they haven’t shifted around
- Finish off that top surface with a slope that lets water drain off properly
Don’ts:
- Get tempted to add extra water just to make the concrete a little easier to pour in
- Allow workers to walk right on the steel and bend it – cant they see that’s just going to cause problems
- Take a long break in the middle of the pour
- Use old or lumpy cement. Its just going to end in trouble
- Have someone drop that concrete from a great height – just dont do it
After Casting: Curing and Shuttering Removal
Curing
Curing is what gives your slab its strength so dont go skipping it. Generally speaking you can start once the surface has set enough, a few hours after casting, and just keep the slab wet all the time.
- Ponding: you can just build some little mud or mortar bunds and have water sit on the slab
- Wet hessian: just cover it with wet gunny bags and make sure they stay moist
- How long: As for how long you need to cure it, your engineer will tell you exactly how long to go for. A general rule of thumb is for OPC concrete you need at least 7 days, and for blended cements like PPC you are going to need at least 10 days – especially if its a dry spell.
Shuttering and prop removal
Removing props too early can cause sagging or cracks. Remove shuttering only when your engineer says so. As a general reference for OPC concrete in normal conditions:
| Item | Typical minimum time |
|---|---|
| Slab bottom shuttering (props left in place) | About 3 days |
| Props under slabs (span up to 4.5 m) | About 7 days |
| Props under slabs (span over 4.5 m) | About 14 days |
Times vary with cement type, weather and design. Always follow your engineer’s advice.
Cast with Confidence with AmritCem
“Roof to Foundation Dhalai” isn’t just AmritCem’s tagline. It’s the promise behind every bag. AmritCem is trusted by home builders, masons and contractors across Assam, Meghalaya, Tripura and West Bengal for the pours that matter most.
👉 Planning your Dhalai? Talk to your nearest AmritCem dealer to plan your cement quantity and delivery for casting day.
Frequently Asked Questions (FAQs)
1. What should i do before taking on roof casting ?
Make sure the engineer has given the thumbs up on the shuttering and steel, that the shuttering and props are strong, level and not about to buckle, that the reinforcement is exactly as shown on the drawings, cover blocks are in place to keep things tidy, conduits and sleeves are securely fixed, all materials and equipment are on site and ready to go, that the labour force is booked to start at the appointed time, and that the weather isn’t going to do anything silly.
2. What’s the ideal time of day for roof casting ?
Try to get underway early-ish in the morning, that way the pour should be wrapped up before dark. In hilly areas where the nights are chilly, an early start is a good idea to make sure the concrete has a chance to set before the temperature drops.
3. How long should a roof slab take to cure ?
As a rule of thumb you should give an OPC concrete roof slab at least 7 days to cure, but with blended cements like PPC it can take a bit longer – at least 10 days, and probably longer in dry weather. Always stick to what your engineer recommends.
4. When can i take away the shuttering after roof casting ?
As a rough guide for OPC, you can start to remove the bottom shuttering about 3 days after the pour, leaving the props in place for a bit longer. For spans up to 4.5m it’s usually safe to remove the props after a week, but if you’ve got longer spans you might need to leave them in for two weeks. Just make sure to follow your engineer’s advice.
5. Can i do roof casting in the rain ?
No, its best to avoid it if at all possible. Rain will just wash away the cement and muck up the all important water-cement ratio and finish. Keep an eye on the forecast and have some polythene sheets on standby in case of a sudden downpour.
