Minimum Standards for Structural Design | RCC Structures

Thumb rules for Structural Design | RCC Structures

I highly recommend use of advanced structural design software like ETabs or Staad Pro for design of structures. This is very important. There are so many variables in design of a structure that no minimum standards can be accurate. This guide can be used for design of very small structures, maybe up to G+1 floors. But I would still recommend use of professional software. Every structural designer should learn these software. Use of manual methods is outdated. Manual method is only used for checks. Real design is done with the help of computers, with very advanced design concepts like pushover analysis, seismic analysis, wind loads simulation and many advanced methods.

You can hire me for your structural design need. Contact me.

Design of RCC Structural Components

In this article, I will discuss the minimum standards that can be followed for the design of RCC structural components of a structure, such as columns, beams, slab and foundation. We will also discuss the minimum safe standards for the reinforcing bars that are to be used for the design of the above mentioned Structural Components.

Minimum cross-sectional dimension for a Column: is  9″x 12″ (225 MM x 300 MM) which is the minimum recommended size. I have designed hundreds of buildings, and never had the misfortune of any structural component ever failing due to loads. I always use M20 grade concrete for construction, as it is the minimum recommended grade of concrete is IS 456:2000. Please don’t skimp on the quality of concrete. The minimum steel in a 9″ x 9″ column is 4 bars of 12 MM with stirrups of 8 MM steel rings at a distance of 150 MM centre to centre. In a 9″ x 12″ column, I add two more bars, to take the total to 6 bars of 12 MM diameter. This design can be safe for up to G+1 floors. But there are a lot of other factors involved.

Also check out:

Thumb rules for making a Column Layout

Construction on Site | Design of RCC Structures

Construction on Site | Design of RCC Structures[/caption]

Minimum RCC beam size should not be less than 9″x 9″ (225MM X 225MM), with an additional slab thickness of 125 MM. I generally use a minimum of 4 bars, with 2 bars of 12 MM thickness in the bottom of the beam, and 2 bars of 10 MM at the top of the beam. I maintain a concrete cover of 40 MM. I recommend use of M20 grade of concrete (1 part cement : 1.5 parts sand : 3 parts aggregate : 0.5 parts water).

Minimum thickness of RCC slab I recommend is 5″ (125MM) because a slab may contain electrical pipes embedded into them which could be 0.5″ or more for internal wiring, which effectively reduces slab depths at certain places, causing cracking, weakening and water leakage during rains. So, a minimum thickness of 5″ should be maintained.

Minimum size of foundation for a single storey of G+1 building, where soil safe bearing capacity is 30 tonnes per square meter, and the oncoming load on the column does not exceed 30 tonnes, a size of 1m x 1m should be used. Minimum depth of footing should be atleast 4′ below ground level. It is recommended to go to depths up to had strata.

Reinforcing bar details (minimum)

1. Columns: 4 bars of 12mm steel rods FE 500

2. Beams: 2 bars of 12 mm in the bottom and 2 bars of 10 mm on the top.

3. Slab

a) One Way Slab: Main Steel 8 MM bars @ 6″ C/C and Distribution Steel of 6 mm bars @ 6″ C/C

b) Two Way Slab: Main Steel 8 MM bars @ 5″ C/C and Distribution Steel of 8 mm bars @ 7″ C/C

4. Foundation: 6″ of PCC layer comes first. Over than, a tapered or rectangular footing of 12″ thickness is minimum. Steel mesh of 8 mm bars @ 6″ C/C should be laid. In a 1m X 1m footing, this would consist of 6 bars of 8 mm on both portions of the steel mesh.

126 thoughts on “Minimum Standards for Structural Design | RCC Structures”

  1. Dear Sir,

    My mason has used M15 grade of concrete in G+1 roof casting. What should I do now? Should I break the roof and reconstruct?

  2. Hi Benzu,

    I got my buolding built by a contractor who did not seem to have consulted a structural or a civil engineer. The dimension of the hall is 32X33 feet. He has raised de walls with three concrete belts one at de foundation, second at de lindal level (7 ft) and 3rd at de roof level. There are no columns in de design. There are 4 big 32 ft long beams across de hall , so distance between each beam is 10 ft. 2 beams r built top of de end walls and hence dey look supported by de walls. The other 2 beams in de centre are landed on the sidewalls. There is no columns in between. Now my friends r saying columns (pillars) are mandatorily required to support the load. The buiding has ground floor only and I dont wish to build any more floors on top of this.
    1)Is it true that de said brickwalls cant withstand de load even though there are concrete belts at three levels?
    2) Some frends r suggesting to build pillars outside de building to support the beams. Is it necessary?
    3) will it help to have a column in de centre of de beam to support the load?

    • This is a complete disaster. Why did you not consult a structural engineer? This is extremely dangerous. I can not really advise you over an email or a message. You need to immediately seek help from a certified civil/structural engineer and get the problem sorted.

    • Hey I don’t know about your complete building design but for your notice they’re actually two kind of building construction. One is the load bearing type and the other one is framed structures. Framed structures, like the name itself is a bonded frame between beams and columns. The foundation of the same will be the column footing and plinth consist of a tie beam along all the columns. In this type of construction all loads of the slab are transferred to the beams, which are again transfered to the columns and dispersed into the footing. This kind of construction is much safer than load bearing structures when it comes to g+2 types of buildings. Also in this the walls generally fulfill the purpose of protection and partition of rooms from external and internal disturbances. There’s no other role for the walls.

      But when it comes to load bearing walls, all the loads from slabs and beams are tranfered to the walls only. No columns are mostly required, in some cases for very long beams and heights support pillars or brick columns are provided. Also the load from brick walls are transferred to the foundation, foundation maybe of Random rubble masonry. So you don’t need to be worry about the things. But it will be better if you consult a licensed Civil Engineer (structural) to nullify your worries. Have a great day!

  3. Hi,
    we need your help you can tell me about 70 tons load beared RCC Flooring how much design PCC 1:4:8 thickness, RCC 1:2:4 Thickness & Steel bars spacing, kindly suggest me.


  4. hi benzuJK
    im planning to build a 3 storey house.ground floor a shop/store next floor and last would be a house..i ask for a foreman he suggest to use 12mmx6pcs steel rod for foundation..8 foundations for the GF. the rest of the steel rod is 10mm..what can you suggest for a better/secure foundation and size of an steel rod to be used? i ask sonce i dont have knowledge for construction of the house..

  5. Hi sir I want to know what’s the height or how many feet the measurement of from frooring to slab of two storey house

  6. You must have to read the requirements in the building code. Take note of the minimum size of re-bars to be used. In a country like the Philippines, where earthquake is a natural calamity and phenomenon expected..then you have to level – up your design. better consult a civil/structural engineers. Dead loads, live loads and even moving loads ( horizontal and vertical) must have to be keenly considered in coming up with you RCCs.

  7. hello mam

    i have newly constructed small bunglow… in the slabs we have used 8mm bars at 6 – 7″cc … is this enough for the slabs?

    and second question is my porch aria slabs is at bottom level of the beam so for the leveling we have filled this area with Brickbat coba around 10″ depth…. is this will over load to the slab or is it ok?

    pls consult about is


  8. Sir, I constructed g + 2 floors in 1200 sqft. area. in 2nd floor in between colums of 13 feet, they used concealed beam in RCC slabs itself and surrounded by bricks wall ( i.e. East to west is 28 feet and followed by 3 coumns and surrounded by brick walls for last 2 columns) and from Centre columns to the last coumns, they adopted concealed beams and above the concealed beams we constructed one room also. can u pls tell me, concealed beam will take a load bearing.

  9. I have a house with 29 pillars (plus 2 brick pillars) of 9″x12″ spread over an area of approx 3200 sft in an hilly area. The roof height on the ground floor is 10 sft. I wanted to increase the column height (more than 10 ft) for the roof on first floor. What is the maximum safe floor height for the building?

    • It is good that the columns are rectangular, so you avoid the problems that come with slender columns. Use stronger concrete, something like M25 strength concrete for columns, and you could go to 15′ without issues.

  10. Hi Benzu,

    Thanks for the valuable information which is very very helpful for individuals like me. It helps me to evaluate the structural design given by my architect is as per standards or not. I am constructing a G+2 Building in 30*50 site. The distance between the columns is 26 feet and my architect suggested to use 9*15 columns. Can you please let me know if that is fine and how far is it safe? Thanks for your time………

  11. Hi, Sir/ Madam.

    Thank you for shearing valuable information. I am planing to build a G+1 store in 1400 sq ft as of now but in future will add a another floor as well, my Civil engineer has given me the mix design of column 12mm, 10mm and 8mm rods will be used for column, will that be good enough. Or i will as him to use 16mm all sides. My budget for construction is 30 lakhs, what can be done by that, Only construction ? I ask for stainless steel railing, a balcony, a small sit out in trace, inbuilt Led lights, and one tub for kids, Engineer is charging me extra for that. what does the 30 lakhs will do. please help me out.

    Thank you.

  12. Sir, I just started my construction project occupying a surface area of 13 * 19= 247sqm. G+1…The upper floor is comprised of four studios ( each is made of a sitting room, bed-room,kitchen and toilet). The columns are 30 ( supporting pillars) and 4 veranda pillars for the ground floor ( total of 34). Each column is 9*9 inches containing 6 10mm steel rods. Foundation on a dry area with foundation blocks filled with mortar and all foundation edges bound together with 10mm steel rods. Advice if the design is solid enough to withstand adverse conditions. Thanks.

  13. Sir the distance b/w my pillar column is 16ft and column is 12*9 and steel bars are of 12 mm 6 in no is it safe my house
    Built Area is 2400sqft

  14. My residential construction is going on. In our building Column beam is closed in ground floor and our engineer advice us for first floor Column beam is not required. Is it advisable one?

    Durairaj. G

  15. My residential construction is going on. In our building Column beam is closed in ground floor and our engineer advice us for first floor Column beam is not required. Is it advisable one?

  16. How much quantity of 16mm and 12 mm steel rods ( indus make ) required for 8″ x 18″ column for 4 story commercial building.
    pl reply for my email

  17. I want to know about your site because i have to design the structure for my project which is an apartment.
    As I’m an architect i always need structural designers for my various projects.

    • Hello Ahmad,
      Since you are an architect, you do understand that civil engineering is a technical field. It is always recommended that we get our homes designed by civil engineers in order to avoid structural instability that might result.
      I am an Architect and a planner. I have Civil engineers in my team which is why I understand the complexities of structural design. Although there are projects which I can do myself, I still prefer getting it done by structural engineers. It just gives me 100% confidence that this cannot go wrong. Do get in touch if you ever need help.

      Kind regards,

  18. Sir Some authors mentioning the safe bearing capacity of clay soil 25t/m2 and some one 30t/ is confusing pl guide me.thanks

  19. Thanks a lot. I felt very much satisfaction after gone through your site..i found many clarifications. Good regards Ifteqar Ahmed civil Engineer

  20. Hello mam
    myself rahul i took land and its water logged area i want basement and ground floor to be constructed so what are the precautions should be taken before and after construction.

  21. Sir,
    I would like to make G+1 (25’x28′)=700 sft 4nos shop and to be 10″x10″ column. So, please let me know how many column I can provide?

  22. Dear sir, i am constructing building of 1600 sq ft with 20 column ,maximum column distance is not more than 12 to 14 ft, for slab 01 eng is suggesting to use both side 8mm Tata rod & other is suggesting one side 10mm rod and other side 8mm rod, this is ground floor slab i want to make G+1 floor, can you inform me which one right.

    • What are the axial loads and bending moments acting on your columns? Please design according to that. Personally, in my designs, the minimum steel rods used are of 12 mm diameter. Strong columns are essential for the longevity of the building. Also, please hire good engineers who know what they are doing.

  23. Thank you. Looking for some good aparment under construction, I located the multi-storeyed “Prestige Downtown” in progress in Vembuliamman koil street, West K.K. Nagar, Chennai. 78. The columns in superstructure have a uniform slender sectional dimention of 6”x24″ throughout. CMDA approved plans are not kept at site. Only, the builders plans for construction is available. i felt this is not in conformity with the Indian standards. i wish to be clarified on the following to enable me to proceed further:
    -Is it approved by CMDA?
    -has it been verified at site by CMDA?
    -are the set-back conditions as approved?
    -is check by CMDA on the dimentions and quality of construction happening as per norms?
    i shall be much obliged for a prompt reply.-

  24. i have one industrial purpose shed and have 9*16 pillar (4+4)
    height is 18 feet and thay keep just steel roof no concrete slab now i want slab of 6 inch on it and want further one floor on it size of shed is 17*40 feet
    please do guide me if you reply i ask further more i like to ask about changes i need to do

  25. Dear Sir/Madam
    I am planning a double storey in 2200sft (GF~1400 and FF~800). Architect has given the following foundation: 20cm PCC bed concrete/60cm Rubble masonry (upto Ground)/then 45cm rubble masonry and 12cm Plinth beam RCC upto Plinth. Load bearing clay brick walls for super structure. The lintel beam is also of 12cm depth. My doubt is whether we should go for 15cm plinth beam and lintel beam instead of 12cm beams? Is 12cm sufficient or 15cm thickness better.
    The soil is lateritic
    John Mathew

    • Hello John,

      I am not trained to design load bearing structures. So I wouldn’t know for sure. But bigger is always better, so you could use 15cm plinth and lintel beams instead of 12cm to be on the safe side.

  26. pl give me details for constructing a large rcc undergound tank, 500 kilo litre, for our community to collect rain water.

  27. Hi
    I am a civil engineer and I am currently planning on constructing a G + 2 bungalow of 3138sq ft ( 1130+ 1258+750). I have done a trial pit for the foundation depth. there is 2 ft of black cotton soil and there after the strata changes to a brownish soil mixed with stones
    I will be doing soil testing in a lab.
    Can you advice me what is the safe bearing capacity required for a RCC framed structure, having columns and footings with slabs
    Thank You

  28. Hi Benz!!
    I really find this site educative..I am a new bee in this field..I am now planning to construct a 2-storey residential house with my 25cmX25cm column with 4-20mm rebars is safe? Average distance between column is 3.5m..waiting for your valuable comment..thanks a lot.

  29. in hollow block slab ,when we provide hidden beam for that load calculation for slab purpose to be taken from center to center

  30. Dear Benzu,
    I have been searching the net for some advice on structural design & it appears u can help me.
    I am trying to build a terrace garden on the roof of my 2nd floor flat in a area of 650 sq. ft.(total area of roof is 1500 sq. ft.). The columns are 10’x9”x15” (16mm-8 pcs & 8mm-4pcs steel), beams are 9″x16″ (16mm & 12mm steel) and the lintel is 125mm thick with 4″ & 5″ steel & is 4″ thick. All are RCC structures.
    I have got done the water proofing of the roof.
    My query is whether the roof can withstand load of 2″ of gravel + 2″ of stone crush sand + 8″ of soil and live load.
    I had consulted a few civil engineers who said yes it can but somehow they could not satisfy me with their reply.
    If u could guide me how to calculate the load bearing capacity of the structure and also please give tentative advice whether the structure can bear load (though i feel i am missing some information that u may require to calculate).
    Many thanks in advance.

  31. Hello BenzuJK,
    I am writing you for my own house building and have some questions. I want to build 6 x 14 meters two-story RCC building with concrete Saltbox roof-slab of 4.5″ thickness and 15 columns for building joints. Building is residential with live load of about 750 lbs. please if possible tell me about the Minimum Standards for Structural Design of mentioned building because I am not able to pay for a local civil engineer and I will build mentioned building during 2-4 years to cover expenses for.

    Regards and Thanks,
    From Afghanistan

    • There are no minimum standards that can be used. Total load on every column has to be calculated in order to design the column and its foundation.

      The load carrying capacity of a 9″x9″ column with 4 bars of 12 MM steel rods upto a height of 10′, with M15 concrete, is 30 Tons. That is the minimum, but in some practices, a minimum of 9″x12″ column is designed for slenderness ration factor. The design depends on a lot of factors, and is not black and white…

  32. hello madam,
    i am in the process of construction of my house. please guide me regarding the depth of footing to be taken once the hard strata is reached.
    yoursuggestion is extremely valuable.
    dr tushar date

    • Hello,
      Structural design is different for structures located in different places. It has to be done accordingly.
      I suggest you consult a local civil engineer for the purpose of Structural design and not do it yourself. This will ensure the safety of your house and your family.
      These articles are mainly for educational and knowledge purpose.
      I hope my suggestion will be taken into consideration by you.


  33. madam what should be the thickness of concrete in a foundation and the size of slab for G+2, as i read out that for G+1 a minimum size is 1mx1m and the thickness is about 15 inches is enough.

    • Hello Gautam,
      All these depend on structural calculations. The loading calculations are very important in this case. The structural design depends on the plan of the building to a large extent. The planning determines the loading conditions on the structure. After having calculated the loads, the quantity of concrete and steel is calculated.
      I suggest you consult a local Civil engineer before taking any step. However, I would like to share a good news with you. We are launching a new business website where people can get their structural design done at minimal rates without having to go through much trouble.


  34. Dear madam

    i have seen the apartment towers are constructed by column size 6″ x 18″
    which Standard to refer for this minimum column dimensions?

  35. Dear Benzu,

    I am very much impress from your articles like one in the link below:

    which seems to be a local project. I do prefab construction on a moderate scale which is not very popular here and therefore also want to diversify into RCC works. Can you please help me in providing structural engineering consultancy for my projects on professional bases? I live in Karachi Pakistan.

    Please let me know as soon as possible if you can help me.

    Darman Nayyer

  36. sure madam, too good advice not to be ignored. hoping to learn more. once again thanks’. always at your website………………

  37. thanks a lot for the info because it helps us save from dubious consulting fees and it really helps us understand the real objective of construction design which is economy and feasibility.more power

    • Hello,
      We are glad that our articles have been helpful to you but it is to be remembered that you always consult a local Civil Engineer for the safe construction of your building. Gaining general knowledge about structures will prevent you from getting cheated but do not initiate the construction on the basis of your theoretical knowledge. An expert from the field of Structural Engineering has to be necessarily involved in the designing and construction of the building.

      • In my house the hall size is 14’x14′. It has beams from three sides of size 10″X10″ with 4″inside roof and 6″ hanging. The fourth side of hall has concealed beam consisting of four no. 12mm bar inside 4″ thick roof. Also this side has stairs meeting the roof. Is it safe or is their a need to reconstruct this fourth beam and how??


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