By Mizhaab, E veedu
Gypsum plastering is a method widely opted these days.
Actually, what is meant by Gypsum plastering?
What are the main differences between gypsum plastering and cement plastering?
What are the disadvantages? Is it cheaper?
Let’s check these concerns.
☑ What is gypsum? How is it manufactured?
Calcium Silicate Dihydrate is known as gypsum.
It’s available in three forms:
- mined out of the earth’s crust.
- Obtained as a by-product of salt processing, widely called as marine gypsum.
- Obtained as a by-product in fertiliser manufacturing and also thermal power plants.
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Processing in site:
Gypsum is applied directly by mixing up with water. Occasionally, boarding agents are used for smooth surfaces like concrete areas. Curing is not needed.
☑ How gypsum plastering is differed from cement plastering?
- No need for watering, can even paint the next day. Usually, we do water for the next 10 days after plastering. Here we can save time and water.
- No need to apply putty to get a finishing look, as usually done in cement plastering.
- Chances of cracking are very low. When cement is mixed up with water a heat is produced,it is called Heat of hydration. This brings a chance to have cracks in cement plastering.
- However it is not recommended for outer walls, as well as in bathrooms and kitchen. Gypsum isn’t meant for moist surfaces, as it pulls in the water and increases chance for breakage.
- Experienced people say that gypsum plastering offers low- heat in rooms. Precisely, advantage of gypsum over cement plastering.
- Quick construction: Sand cement plaster demands 28 days of curing and more. While gypsum just demands three days.
- Saves water: sand cement plaster requires 0.6 kilogram/ m 2 tune of water per day. 60000 litres of water is essential for a project of 100000 sqm per day. If the minimum days of curing is 28, the quantity also increases.
- Cracks: Cracks may appear in sand cement plastering (after effect of dryness). But not in gypsum plastering.
- Light- weight construction: In comparison with traditional sand cement plastering ( 1860 kg/ m 3) gypsum plaster ( 700 kg/ m 3) has 50% less density.
- Low- electric bills: In comparison with sand cement plastering (0.72 w/m k) this has low conductivity. Works as a cooling agent in heat and heating agent in cold. So, profit in power expenditure.
Know this on beforehand👇
In plastering the thickness of exterior, interior and ceiling are 20, 12 and 9 mm respectively.
- Exterior – 20 mm
- Interior – 12 mm
- Ceiling – 9 mm
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The most appropriate mix for vertical walls is 1: 4.
1:3 is best for ceilings.
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Fly Ash basil cement a.k.a. PPC grade cement is suitable for plastering.
P sands or plastering sands are to be used for plasterings.
Expenditure of 1100 sqft house:👇
( 1100 is the measurement of the floor. May vary according to the height of the walls and the plan)
Let’s look at the plastering cost of an 1100 sq ft house in general.
There would be 1400 Sqft for plastering, and we are not to consider doors and windows here.
Specification: 1400 sq ft, 2.6 cum (cubic metre), 20 mm thickness.
Material required: 20 bags cement, 95 CFT P Sand.
Specifications: 3500 sqft, 3.9 CUM, 12 mm
Materials required: 29 Bags cement, 143 CFT P Sand.
Specification : 850 sqft, 0.92 CUM, 9 mm
Material Required: 7 Bags Cement, 25 CFT P Sand
Shades / Terrace
Specification : 1600 Sqft, 3.9 CUM,12 mm
Material Required: 29 Bags Cement,143 CFT P Sand
Total = 86 bags cement
414 CFT P Sand
Including wastage = 90 Bags Cement,
455 CFT P Sand
Briefly the expenditure for cement plastering is:
Cement rate : 90 bags of cement × Rate ( 460) = 41400
P Sand Rate : 455 CFT × 56 (rate) = 25480
Labour cost : 7350 sq ft ( sq ft for total polish, not floor measurement) ×14 = 102900.
Total = 169780
Expenditure of 1400 sq ft house when considering Gypsum plastering :👇
As we have discussed earlier gypsum plastering can’t be done to a whole house. Interior and exterior of bathroom walls, ceiling ( if designing with gypsum boards) needs to be excluded i.e, the interior walls of each room ( by reducing doors and walls but calculating borderline in running feet).
Approximately 2500 sq ft.
Various gypsum plastering brands are available in the market. The rate may vary from 35- 45 based on quality and brand.
Let’s check it out with 35 rupees:
I.e, 2500 x 35 = 87500
As mentioned above, all areas cannot be done by Gypsum plastering. Let’s check the cost of doing cement plastering in the remaining area.
Roughly the cost of cement plastering for exterior + interior bathroom walls + ceiling ( where gypsum isn’t done or can’t be done) is:
Cement bags = 67 x 460 = 30820
P Sand = 333 x 56 = 18648
Labour = 67900
Total = 117368
In total, The gypsum plastering cost on an 1100 sq ft house is approximately, 117368 + 87500 = 204868.
Rate of cement plastering = 169780
Rate of gypsum plastering = 204868
Then how could it be low-cost?
Rate is reduced in the finishing stage.
👉 if it is just cement plastering
- Needs to apply white wash
- Two coats of putty is to be done
- Needs to apply primer
- Painting is needed
👉in the case of gypsum plastering can paint immediately after one coat of primer.
Now let’s sum up the cost
The example chose (1100 sq ft) has an area of 2500 sq ft with gypsum. We have already calculated the rate.
The same area for cement plastering is:
Cement = 23 ( Bags ) x 460 ( cemet rate ) = 10580
P Sand = 110 ( Cft) x 56 ( rate ) = 6160
Labour = 35000
White cement = Material + Labour = 8750
2 Coat putty = Material + Labour = 45000
Total = 105490
Remember the rate of 2500 sq ft gypsum plastering is 👉 87500.
At the same time, if we are using high-quality gypsum of rupees 42, the cost will be 👉 2500×42 = 105000.
Precisely what we have recognised
Usage of gypsum on rupees 40 to 48 will be equal to cement plastering and then applying putty. 35 to 37 rupees gypsum will reduce the rate.
Advantages discussed earlier:
- No cracks
- No need for curing process
- Save water and energy
- Rapid constructions e.t.c.
Gypsum plastering is suitable for these concerns.
At the same time, if the budget is low it’s better to go for cement plastering and then to whitewash.