Foundation of any building is most important as it is the strong base upon which the whole structure is situated. Due to several reasons, a building may require the foundation to be revamped. According to the specific requirements, re-blocking, re-stumping, and underpinning may be recommended. Therefore, it’s important to understand the difference between these procedures.

Re-Blocking and Re-Stumping

Basically, there is hardly any difference between re-blocking and re-stumping as the terms are used interchangeably when the foundation stumps have to be replaced. The basic procedure remains same for both these procedures. These procedures are done when the wooden or concrete stumps which support the building begin to disintegrate.

The process of re-blocking or re-stumping involves removing the old foundation while supporting the whole structure by placing jacks beneath. The worn out stumps are removed and new stumps are placed.

The foundation stumps are worn out over time depending on the age of the house and the type of clay or soil beneath the structure. Wooden stumps, which were used in olden times, can also become prey to termites and weathering due to the forces of elements. Therefore, these are usually replaced with concrete stumps. To make the base stronger for at least two decades, concrete may be poured in the gaps between the stumps.

Reblocking

Reblocking

Underpinning

Underpinning doesn’t involve removal or replacement of the stumps but rather making those stronger. If the building has concrete foundation and walls are made from bricks, then underpinning is more appropriate. Over time due to weather conditions, the soil may become hard leading to the concrete slabs to subside or the walls getting cracked. This results in the floors getting misaligned and the walls to crack. This can be dangerous if not tended to in time.

How do the procedures differ?

  • The main difference is in the way the foundation is restored. While in re-blocking and re-stumping, the stumps are replaced; in underpinning, the stumps are repaired rather than being replaced.
  • In re-blocking and re-stumping, the floors are also reset.
  • If the structure was built long ago in the early 1990s or even earlier, then re-blocking or re-stumping will be required as the foundation must be replaced with more concrete and durable materials.
  • If floors are uneven, doors are not locking properly and walls are getting cracked, then re-blocking or re-stumping will be recommended.
  • Buildings that are more recent and had been witnessing wall cracks and misaligned floors may be recommended underpinning. The cracks may be due to soil conditions and a repair work can prove to be beneficial.
  • Re-blocking and re-stumping may cause minor cracks in plasters on walls which can be easily repaired.
  • Underpinning involves stabilizing the soil while re-blocking and re-stumping involve replacing the stumps.
  • Re-stumping and re-blocking are meant for structures which stand on stumps while underpinning is meant for structures having brick or concrete veneer.

Consulting underpinning professionals can give a clear view regarding the problem and which method will be most beneficial.