The amount of cement, sand, and lime you need for rendering depends on several factors, including the thickness of the render, the surface area to be covered, and the specific mix ratio you want to use. Common mix ratios for rendering are 1:1:6 (cement:sand:lime) or 1:3:12, but these ratios can vary.
Rendering is the process of applying of lime cement mortar to external, internal or partition brick/ block walls to achieve highly finished, good texture and smooth surface, which give us aesthetic and beautiful appearances, it should be waterproofing and fire rating qualities.
The main ingredients of renders are Portland cement, sand, lime, water and some approved admixture, mix ratio for rendering is 1 parts Portland cement to 1 parts lime to 6 parts sand represented as 1:1:6 (1 cement: 1 lime: 6 sand), this mix can be used for first coat and finished top coat for external and internal wall.
Any general purpose cement can be used and sand must be fine rendering sand clean and free from impurities. You do not use building sand for rendering because it may causes shrinks and cracks.
Renders is mix with some additives material that increases the bonding strength and slowing in drying or hardening, adding lime in mix increases the plasticity, flexibility and workability that can reduces the chance of cracking after drying. Pigmentation of colour should be done according to aesthetic requirement. A thin finishing top coat can be applied to achieve decorative effect, it can be applied by using trowel, brush or sponge.
How much cement sand and lime do I need for 100m2 rendering
FOR 10MM THICK RENDER
1) Calculate wet volume of mortar (wet volume = 100m2 × 0.01m = 1m3) :- we have given 100 square metre area for 10mm thick rendering, calculate volume of rendering which is equal as quantity of cement lime mortar required, wet volume of required mortar = Area × thickness, such as wet volume = 100m2 × 0.01m = 1m3.
2) Calculate dry volume of mortar (dry volume = 1.27 × 1m3 = 1.27m3) :- as we know that wet volume of mortar is less than dry volume, for equalising factor we will multiply 1.27 in wet volume of mortar to get dry volume, so dry volume of mortar = wet volume × 1.27, such as 1.27 × 1m3 = 1.27m3, therefore dry volume = 1.27m3.
3) taking extra as 5% for wastage (5% of 1.27 = 0.0635m3, total = 1.27 + 0.0635 = 1.33m3) :- taking extra as 5% for wastage during the transportation, storage and mixing at construction site, 5% of 1.27 = 0.0635m3, so total dry volume of mortar = 1.27 + 0.0635 = 1.33m3, it means you will need 1.33m3 of dry mortar for 100m2 of 10mm thick rendering.
3) Render mix ratio is 1:1:6 (1 parts cement, 1 parts lime and 6 parts sand) :- total proportion = 1+1+6 =8, so parts of cement = 1/8, parts of hydrated lime = 1/8 and parts of sand = 6/8.
4) Calculate cement quantity (1/8 × 1.33m3 × 1440kg/m3 = approx 240kg):- as we know that dry loose bulk density of cement is about 1440kg/m3 and one bag cement size is 25kg or 50kg, so cement quantity in kg = (1/8 × 1.33m3 × 1440kg/m3 = approx 240kg, number of 25kg bag cement = 240/25 = nearly 10 bags, you will need approx 10 bags of 25kg cement or 5 bags of 50kg cement (total around 240kg) for 100m2 of 10mm thick rendering.
5) Calculate hydrated lime quantity (1/8 × 1.33m3 × 550kg/m3 = approx 92kg):- as we know that average dry loose bulk density of hydrated lime powder is about 550kg/m3 and one bag lime size is 25kg or 50kg, so lime quantity in kg = (1/8 × 1.33m3 × 550kg/m3 = approx 92kg, number of 25kg bag lime = 92/25 = nearly 4 bags, you will need approx 4 bags of 25kg hydrated lime or 2 bags of 50kg lime (total around 92kg) for 100m2 of 10mm thick rendering.
6) Calculate quantity of sand (6/8 × 1.33m3 × 1600kg/m3 = approx 1596kg):- as we know that dry loose bulk density of sand is about 1600kg/m3 and one bag sand size is 25kg, so sand quantity in kg = (6/8 × 1.33m3 × 16000kg/m3 = approx 1596kg, number of 25kg bag sand = 1596/25 = nearly 64 bags, or 2 bulk, jumbo, or tonne bag (1596/800 = 2), you will need approx 64 bags of 25kg or 2 bulk bags of sand (total around 2 loose tonne) for 100m2 of 10mm thick rendering.
7) Calculate amount of water (20% of 1.33m3 = 0.266m3, 0.266 ×1000 = 266 litres):- generally water needed for mortar preparation based on workability requirement, generally it is ranging from 17 % to 35% of total dry volume of mortar, initially we take 20% of water requirement for preparing mortar, so water quantity = 20% of 1.33m3 = 0.266m3, 1m3 of water = 1000 litres, so quantity of water = 0.266 ×1000 = 266 litres, so you will need 266 litres of water for 100m2 of 10mm thick rendering.
As per UK practice, with a standard cement to sand ratio of 1:4 and a render thickness of 20mm, you will need 800kg cement and 3400kg sand for 100 m2 rendering. Therefore, 32 bags of 25kg cement and 136 bags of 25kg sand are required for 100 square meters rendering.
How much sand and cement per m2 for Rendering
Generally you will need about 0.1 bags of 25kg cement (total around 2.4kg), approx 0.04 bags of 25kg hydrated lime (total around 0.92kg), approx 0.64 bags of 25kg (total 16kg) sand and 2.6 litres of water per m2 (square meter) for Rendering of internal or partition wall at 10mm thick.
As per UK practice, with a standard cement to sand ratio of 1:4 and a render thickness of 20mm, you will need 8kg cement and 34kg sand per m2 for rendering. Therefore, 0.32 bags of 25kg cement and 1.36 bags of 25kg sand are required for 1 square meter rendering.
As per UK practice, with a standard cement to sand ratio of 1:5 and a render thickness of 20mm, you will need 7kg cement and 36kg sand per m2 for rendering. Therefore, 0.28 bags of 25kg cement and 1.44 bags of 25kg sand are required for 1 square meter rendering.
As per UK practice, with a standard cement to sand ratio of 1:6 and a render thickness of 20mm, you will need 6kg cement and 37kg sand per m2 for rendering. Therefore, 0.24 bags of 25kg cement and 1.48 bags of 25kg sand are required for 1 square meter rendering.
CONCLUSIONS:-
Regarding this, “how much cement sand and lime do I need for 100m2 of 10mm thick rendering”, generally you will need about 10 bags of 25kg cement (total around 240kg), approx 4 bags of 25kg hydrated lime (total around 92kg), approx 64 bags of 25kg or 2 bulk bags of sand (total around 2 loose tonne) and 266 litres of water for 100m2 of 10mm thick for internal or partition wall rendering.
Regarding this, “how much cement sand and lime do I need for 10m2 of 10mm thick rendering”, generally you will need about 1 bags of 25kg cement (total around 24kg), approx 0.4 bags of 25kg hydrated lime (total around 9.2kg), approx 6.4 bags of 25kg (tatal 160kg) sand and 26 litres of water for 10m2 of 10mm thick for internal or partition wall rendering.
Regarding this, “how much cement sand and lime do I need for per m2 of 10mm thick rendering”, generally you will need about 0.1 bags of 25kg cement (total around 2.4kg), approx 0.04 bags of 25kg hydrated lime (total around 0.92kg), approx 0.64 bags of 25kg (total 16kg) sand and 2.6 litres of water per m2 (square metre) of 10mm thick for internal or partition wall rendering.
If you want to buy hydraulic lime cement render bags, which is easily available in market, comes in size 25kg weight, you will need about 76 bags of 25kg lime cement render (total nearly 1900kg) for 100m2 of 10mm thick for internal or partition wall rendering. This calculation based on dry loose bulk density of material requirement for preparing lime cement mortar, for actual quantity requirement you should ask to local seller.
FOR 20MM THICK RENDER
1) Calculate wet volume of mortar (wet volume = 100m2 × 0.02m = 2m3) :- we have given 100 square metre area for 20mm thick rendering, calculate volume of rendering which is equal as quantity of cement lime mortar required, wet volume of required mortar = Area × thickness, such as wet volume = 100m2 × 0.02m = 2m3.
2) Calculate dry volume of mortar (dry volume = 1.27 × 2m3 = 2.54m3) :- as we know that wet volume of mortar is less than dry volume, for equalising factor we will multiply 1.27 in wet volume of mortar to get dry volume, so dry volume of mortar = wet volume × 1.27, such as 1.27 × 2m3 = 2.54m3, therefore dry volume = 2.54m3.
3) taking extra as 5% for wastage (5% of 2.54 = 0.127m3, total = 2.54 + 0.127 = 2.66m3) :- taking extra as 5% for wastage during the transportation, storage and mixing at construction site, 5% of 2.54 = 0.127m3, so total dry volume of mortar = 2.54 + 0.127 = 2.66m3, it means you will need 2.66m3 of dry mortar for 100m2 of 20mm thick rendering.
3) Render mix ratio is 1:1:6 (1 parts cement, 1 parts lime and 6 parts sand) :- total proportion = 1+1+6 =8, so parts of cement = 1/8, parts of hydrated lime = 1/8 and parts of sand = 6/8.
4) Calculate cement quantity (1/8 × 2.66m3 × 1440kg/m3 = approx 480kg):- as we know that dry loose bulk density of cement is about 1440kg/m3 and one bag cement size is 25kg or 50kg, so cement quantity in kg = (1/8 × 2.66m3 × 1440kg/m3 = approx 480kg, number of 25kg bag cement = 480/25 = nearly 19 bags, you will need approx 19 bags of 25kg cement or 10 bags of 50kg cement (total around 480kg) for 100m2 of 20mm thick rendering. not taking a decimal, because you have to purchase a full bag size.
5) Calculate hydrated lime quantity (1/8 × 2.66m3 × 550kg/m3 = approx 184kg):- as we know that average dry loose bulk density of hydrated lime powder is about 550kg/m3 and one bag lime size is 25kg or 50kg, so lime quantity in kg = (1/8 × 2.66m3 × 550kg/m3 = approx 184kg, number of 25kg bag lime = 184/25 = nearly 8 bags, you will need approx 8 bags of 25kg hydrated lime or 4 bags of 50kg lime (total around 184kg) for 100m2 of 20mm thick rendering.
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6) Calculate quantity of sand (6/8 × 2.66m3 × 1600kg/m3 = approx 3192kg):- as we know that dry loose bulk density of sand is about 1600kg/m3 and one bag sand size is 25kg, so sand quantity in kg = (6/8 × 2.66m3 × 16000kg/m3 = approx 3192kg, number of 25kg bag sand = 3192/25 = nearly 128 bags, or 4 bulk, jumbo, or tonne bag (3192/800 = 4), you will need approx 128 bags of 25kg or 4 bulk bags of sand (total around 4 loose tonne) for 100m2 of 20mm thick rendering.
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7) Calculate amount of water (20% of 2.66m3 = 0.532m3, 0.532 ×1000 = 532 litres):- generally water needed for mortar preparation based on workability requirement, generally it is ranging from 17 % to 35% of total dry volume of mortar, initially we take 20% of water requirement for preparing mortar, so water quantity = 20% of 2.66m3 = 0.532m3, 1m3 of water = 1000 litres, so quantity of water = 0.532 ×1000 = 532 litres, so you will need 532 litres of water for 100m2 of 20mm thick rendering.
CONCLUSIONS:-
Regarding this, “how much cement sand and lime do I need for 100m2 of 20mm thick rendering”, generally you will need about 19 bags of 25kg cement (total around 480kg), approx 8 bags of 25kg hydrated lime (total around 184kg), approx 128 bags of 25kg or 4 bulk bags of sand (total around 4 loose tonne) and 532 litres of water for 100m2 of 20mm thick for external brick/ block wall rendering.
Regarding this, “how much cement sand and lime do I need for 10m2 of 20mm thick rendering”, generally you will need about 2 bags of 25kg cement (total around 48kg), approx 1 bags of 25kg hydrated lime (total around 18.4kg), approx 13 bags of 25kg (tatal 320kg) sand and 53 litres of water for 10m2 of 20mm thick for brick/block wall rendering.
Regarding this, “how much cement sand and lime do I need for per m2 of 20mm thick rendering”, generally you will need about 0.2 bags of 25kg cement (total around 5kg), approx 0.01 bags of 25kg hydrated lime (total around 2kg), approx 1.3 bags of 25kg (total 32kg) sand and 5 litres of water per m2 (square metre) of 20mm thick for external brick/ block wall rendering.
If you want to buy hydraulic lime cement render bags, which is easily available in market, comes in size 25kg weight, you will need about 152 bags of 25kg lime cement render (total nearly 3800kg) for 100m2 of 20mm thick for external brick/ block wall rendering. This calculation based on dry loose bulk density of material requirement for preparing lime cement mortar, for actual quantity requirement you should ask to local seller.