What is surface treatment?

Generally speaking, foundation is the most important part of a house. However, in order for a properly designed foundation to last a lifetime, it must be placed on solid ground and well treated. This isn’t a new idea but we don't always do it right all the time.

The Gospel of Surface Treatment according to NextHome

Many builders/contractors use filling sand - so what is the big deal? Nothing really but here are the facts for the enquiry mind. Surface treatment is the preparation of the soil in foundation for the DPC stability.

1. Once soil is removed from its original location, it tends to increase in volume because there is less pressure holding the soil particles together.

2. When the filling soil are placed in a foundation as backfill/infill, it is still in a loose state and unless additional steps are taken during the filling operation, it will take a very long time for the soil to compact itself naturally.

That’s fine, if your house isn’t sitting on top of it. It's okay if you aren't building on the sand filled foundation until the end of another rainy season. But if your foundation is going to be sitting/resting on loose/uncompacted soil, then there is likely to be settlement in the fill area producing differential movement in your foundation.

The good news is that this post construction settlement of the soil can be overcome by ponding/compacting the soil while it is being placed. Having water in the sand filled foundation helps the sand to slide together closely.

Now, how much of water is enough? You don't need too much or too little water to get a well compacted soil. You just need little water to moist the soil at layers to achieve good compaction. Too much of water will not give you any good result. Think of sand on a mattress, little water will bring them together. Too much water will on take them apart.

What else?

* Damp Proofing
* Application of anti rust paint on the foundation reinforcement/removal of fill soils from around the foundation pillars. Very important but often ignored.
* Levelling
* Compacting of the soil

Hope my answer is not too disappointing.