Guides
Foundation (niv) material guide
A niv carries four things every time: TMT bar for the cage, cement for the concrete around it, cover blocks to hold that cage off the earth face, and binding wire to tie the crossings together. IS 456 fixes 50 mm of cover at the footing on its own, with no exposure class allowed to bring it lower, and drops to 40 mm at the column standing on that footing, 25 mm where the column is small enough for the code's own relaxation to apply.
- Guides
- 1 table of figures
- Own delivery, 34 blocks
- Open all 7 days
Jay Shree Infra keeps TMT bar, cement, cover blocks and binding wire at the Saharsa godown and sends all four out across Saharsa, Supaul and Madhepura, and a niv order is where those four names first come together on one bill. Not every size is in every brand on a given day. IS 456:2000 is the standard that fixes how much cover a member needs, and its own record shows six amendments since 2000, the last in 2024; the two figures below are the unamended 2000 text, and a drawing or a tender naming a different one governs the job.
Cover, the concrete between the steel and the finished face, is one line among several a niv has to answer. Which diameter and which grade go into that steel is the other, and neither line is a guess this counter makes for you: both come off the drawing, member by member, before anything is cut.
IS 456
The cover a footing and the column on it are fixed to
The nominal cover IS 456:2000 sets for a footing and for the column rising off it, the two members a niv order is built around.
Scroll the table sideways to see every column
| Member | Nominal covermm, not less than | IS 456 clause |
|---|---|---|
| Footing | 50 | 26.4.2.2 |
| Column, longitudinal bar | 40 | 26.4.2.1 |
| Column, 200 mm or under, bars up to 12 mm | 25 | 26.4.2.1 |
The BIS record for IS 456:2000 lists all six amendments; the figures here are the unamended 2000 text. Clause 26.4.2.2 fixes the footing figure flat, without reference to exposure class, so it holds whether the rest of the house is drawn to mild or to severe. Clause 26.4.2.1 fixes the column figure and its own relaxation, and adds a rule that applies to every member and every exposure class at once: cover is never less than the bar's own diameter. A 20 mm bar cannot sit on a 20 mm block regardless of what the table says. The deviation note under IS 456's Table 16 allows up to 10 mm over any figure here and nothing under it.
Fifty millimetres is the deepest cover a typical house is likely to ask for outside a severe or extreme wall, and it is fixed at the footing alone; nothing about a mild or a moderate exposure class brings it down. That is usually the tallest cover block on a niv order, and it is worth naming to the height rather than to a size guessed off the rest of the house.
The column relaxation is narrow. Both conditions have to hold together, a minimum dimension of 200 mm or under and bars no thicker than 12 mm, before the 40 mm figure can drop to 25. A column outside either condition stays at 40, and the diameter rule sits above both figures regardless: whatever the exposure class allows, the block still has to clear the bar it is holding.
What each one does
What the four items are doing in a niv
TMT bar carries the tension the concrete on its own cannot, cut and bent to the drawing's bar bending schedule before the trench takes a single load. Cement is the concrete around that cage, the material actually pouring in once the steel and the cover blocks are fixed and the mixer arrives.
Cover blocks are the one item on this order whose entire job is holding the cage off the earth and the shuttering by the distance the table above sets; the IS 2502 rules on the block itself sit on their own page, single blocks only, never two stacked to make up a height.
Binding wire ties the crossings so the cage keeps its shape while the pour goes in, and the diameter that ties it is its own small question, separate from the diameter of the bar being tied.
Off the drawing
Which diameter and grade a niv usually takes
Shyam Steel's own worked example, published on its site, runs an 8 mm mesh at 6 inch centres under a footing and a 12 mm Fe 500 bar in the column standing on it, with 12 mm and 10 mm bars in the beam between two columns. Those are one maker's own figures for one worked house, not a rule that fits every drawing that reaches this counter.
SAIL's own SeQR brochure names 8 to 25 mm as its published home builder range, wider than either single figure above and closer to the spread a niv and the structure rising off it actually cover between them. A house with a heavier load at the footing, a longer span at the beam or a taller column can sit anywhere in that range and still be inside what one maker's own paper allows for a home.
Both sources agree on one thing without saying so directly: the diameter steps down as the load does, thicker at the footing and the lowest column, thinner higher up. Which exact figure applies to your own niv is the drawing's answer, not either maker's worked example.
At this counter
What stands on our rack for a niv order
TMT bar here runs from 5.5 mm up through 32 mm across the brands on the rack, so both the Shyam Steel worked example and the wider SAIL range sit inside what a single call can cover. SAIL SeQR is the first line we point a home builder to for sariya; Tata Tiscon, Kamdhenu, Shyam Steel and Balmukund stand beside it for the same job.
Cover blocks run in seven heights and binding wire in five diameters; both are read out against the cover figures above and the gauge a cage actually needs on their own pages, so a niv order names a height and a gauge rather than a size taken on trust.
Not every size stands in every brand on a given day. What we can settle on the phone is what a pack in the godown is made of and what is printed on it; the diameter and the grade against each member still come off your own drawing.
Sources
IS 456's own cover clauses, and two makers' diameter figures
The Bureau's own record for the standard, and two makers' own published pages for the diameters beside it.
- The BIS record for IS 456:2000 and its six amendments, source of the cover figures aboveBureau of Indian Standards
- Shyam Steel's own worked example of TMT bar usage in a footing, column and beamShyam Steel
- The SAIL SeQR brochure, with the 8 to 25 mm home builder diameter rangeSteel Authority of India (SAIL)
Questions
Niv ke saman ke sawal
Niv me sariya, cement, cover block aur tar, kitna kitna lagta hai?
Quantity comes off the drawing, member by member, off nobody's guess. What is fixed is which four items go on a niv order: TMT bar for the cage, cement for the concrete, cover blocks for the gap under it and binding wire to tie it together. Bring the bar bending schedule on the call and we read the count against what is standing that morning.
Niv ki gehrai me sariya ka cover kitna rakha jata hai?
50 mm at least, and that figure holds regardless of exposure class. Clause 26.4.2.2 of IS 456 fixes it for the footing on its own, so it stays at 50 whether the rest of the house is drawn to mild or to severe exposure, and it is usually the tallest cover block on a niv order.
Column shuru hote hi cover kam kyun ho jata hai?
Clause 26.4.2.1 fixes the column figure at 40 mm, below the footing's 50, with one relaxation to 25 mm where the column is 200 mm or under on its smaller side and carries bars no thicker than 12 mm. Cover can never come under the bar's own diameter either way, so a thick bar sets its own floor before the column relaxation is even asked.
SAIL ya Shyam Steel ke size hi lene padenge kya?
No. Shyam Steel's worked example runs 8 mm at the footing and 12 mm at the column, and SAIL's own SeQR brochure names a wider 8 to 25 mm home builder range; both are one maker's published figures, not a rule for every drawing. We stock 5.5 mm through 32 mm across the brands on the rack, and the drawing in front of you settles which one your niv actually takes.
Ek hi diameter footing, column aur beam sabki jagah chal sakta hai kya?
It can be poured that way, but the two published examples above do not run that way. Shyam Steel's own worked house steps the diameter down as the load does, 8 mm at the footing mesh, thicker at the column, and a mix of 12 mm and 10 mm in the beam between two columns. Order by member off your own drawing rather than one figure for the whole niv.
Before you order
The drawing answers these first
Is this order for the footing, the column, or both?
Cover and diameter both hang off the answer: 50 mm at the footing, 40 or 25 at the column.
What diameter and grade does the bar bending schedule name?
Read it straight off the schedule where one exists. Shyam Steel's and SAIL's own figures are for orientation, not for your own order.
Is any column 200 mm or under on its smaller side, with 12 mm bars?
That is the one case IS 456 lets the cover drop to 25 mm. Outside it, the column stays at 40.
How many pieces of each diameter, and which day is the trench ready?
The count comes off your side; the day decides when the load leaves here.
Contact
The bar schedule settles the niv, one call sends it
Bring the member, the diameter and the grade the drawing names, footing, column or both, and we read out what stands against them today, cover block height and wire gauge included. Ring +91 6202 967 218 with the count and the day the trench is ready, and the niv order goes out complete in one call.
Shop hours: All 7 days, 9:30 AM to 6:00 PM