Hardcore Filling: Meaning and Importance In Building Construction


If you’ve actually built up to the DPC level and done filling, your next question would be “Should i apply hardcore too”?, well, if that is your question, i am not going to say “Yes”, i also am not here to say “No”, i will leave you with a better understanding of the importance of Hardcore in a building.

What is Hardcore 

A Hardcore is a layer of a building immediately after filling. It comprises of stones, boulders as the case may be. Materials used in hardcore includes broken blocks, bricks, larger sides of granites, etc.

See Images Below

hardcore for buildings
Photo Credit: Google Image

When Do I use Hardcore?

If you’ve built to DPC level, you may need to apply hardcore after filling up to a level almost the same with the last block on the wall. Hardcore is applied after filling the internal part of your foundation. This filling may be with laterite or sharp sand.

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On filling, ramming may be used to compact the soil in order to avoid voids which may exist within the soil.

After ramming, it is then necessary to apply rods/wire mesh and comcrete.

You can see the image below for a better understanding of what is explained here…

compacted hardcore
Photo Credit: Google Image
Professionalism requires that a certain amount of space be allowed to contain the hardcore layer and this is accompanied by the space for concrete.

That however is for the books, but i will tell you here today that getting the thickness for hardcore is always difficult and may not be regarded as important as it is stressed in books, that however is as a result of crude methods of construction, experience of the builder and the settlement pattern of the natural soil as the case may be..

What are the Importance Of Hardcore In a Building?

For the importance of applying hardcore in a building, quickly read the following points as i believe they would explain better…

1. Hardcores are important for the stability of the foundation
2. It further adds strength or solidifies the base upon which the german concrete sits on. This means that it helps to resist pressure of dead and live loads on the ground floor as it helps transfer this to the foundation.

3. Hardcores provides a good base for buildings. It serves as a platform for the base of the building.

4. Application of hardcores helps to save cost.This is because the amount of cement and granite that would have been used for oversite concrete is reduced as stones or boulders are used to reduce the depth of void

5. Hardcores provide space for air. This exists between the hardcore system and serves as restriction to the movement of water.

6. Hardcores helps to shorten the time required for casting.This is so because the amount of concrete required to cast is totally reduced on addition of stones.

7.Hardcores are very important as they help protect the substructure (Foundation). It however saves cost of maintenance, underpinning in the future.

What is the Required Depth For Hardcore?

Specification for hardcores are usually 300mm or 30cm or 0.3m thick

section of a foundation

This is followed by a 150mm thicklayer of oversite concrete and all of these rests on a very thick layer of earth filling.

Also note that hardcores are only necessary in the ground floor. It is not required in upper floors as the slab is the only hardcore requires above

Now you have learnt the meaning and importance of application of hardcore as it applies to your construction. I am hopeful of the fact that this has helped you understand something and so you can share with your friends by using any of the social media icons below this post.

Written by admin

Hi, I'm Richard Nwachukwu! It is my job to handle the content aspect of this great organization and I'm determined to ensure you get it all right as long as you're handling a construction project in Nigeria!


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  1. Its always good to learn tips like you share for blog posting. As I just started posting comments for blog and facing problem of lots of rejections. I will let you know if its work for me too. steel foundry

  2. All what you said are according to the book. There was no reasons for or against what would enable one make the decision of either or not to apply the hardcore materials before the over site concrete is laid.
    Let me state here that one can decide to apply the hardcore materials before the over site concrete is laid if the materials used for earth filling is expensive or cohesive for example peat soil or mud. When non expensive or cohesive soil such as granular sand or high quality latrite is used a 150mm thick of concrete of grade C15 i.e 1:3:6 mix will carry the live load that may be applied on the floor.

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