For RCC works the wastage is 2.5% for reinforcement rods above 36mm dia. and 5% for rods below 36mm dia. including overlaps, if they are not welded. If welding is adopted for the reinforcement rods even for below 36mm dia, 2.5% of wastage is recommended.

While estimating quantity of concrete for particular structural work, we normally consider 3-5% as wastage. But wastage of concrete more than that can increase the cost of project and may impact project progress.

Since 1m³ corresponds to a volume of 1,000l, you therefore calculate 1,000 / 21. 48 rounded bags of ready-mixed concrete of 40 kg each or a total of 1,920kg of ready-mixed concrete per cubic meter are required.

To mix 1 cubic metre of concrete by hand you need 1.5 tonnes of gravel 0.75 tonnes of sand and 10 bags of 20kg cement then add clean water. The weight of 1 cubic metre of concrete is approx 2400kg. To work out the volume of concrete always remember length x width x depth.

Considering the support constraint, rebar is undoubtedly stronger than wire mesh. Several constructors consider rebar for domestic jobs. For thicker driveways and locations that involve greater traffic, rebar is always a good option to consider.

For a garage WITHOUT a floor – BUILT ON SITE: Prepare a level concrete slab at least 4” thick and to the exact, outside, dimensions of your garage. You may want to consider a 6″ thick slab for larger vehicles such as trucks or RVs.

While for sheds, a concrete foundation is optional most of the time, a garage foundation is essential. It’s best to plan for pouring a concrete garage foundation before you begin building.

The IRC requires that slabs be built with concrete with compressive strengths from 2500 to 3500 psi, depending on the climate. ACI goes further and recommends 4500-psi concrete for garages in the northern half of the country.

The cost of a 30 x 40 Quonset garage begins at about $10,000. Accessories and delivery are an additional $2,500, bringing the total estimated cost to roughly $12,500. If a foundation is needed for a prefabricated steel garage, its cost will add another $4 to $8 per square foot.

No, rebar is not required. Garage floors are poured last. Generally the thickness is usually about 4″ minimum plus. Many builders will not use rebar, nor do many provide control cuts.

I always pour garage floors after the house is framed, this is usually industry standard practice. The garages are back-filled with the foundation so you want for the dirt to settle before you pour a slab.