If there is a well or soft water store near your new foundation, the main concern is that any future deterioration of the walls of the well will lead to the migration of the surrounding soil into the well which will result in foundation subsidence.

The simplest solution (though not always the cheapest) is to fill the well with concrete to prevent this happening. If it is possible to do this you will need to make sure the the new foundation doesn't sit directly on top of the concrete. There needs to be a layer of compressible material between the new foundation and the infilled well, to prevent creating a hard spot which will lead to cracking in the building as it settles.

Often it is not possible to fill the well in because it is already full of rubbish. Whilst it may look full, even if brick rubble has been used there will still be around 30% voids and so the problem remains.

In these circumstances the best solution is to reinforce the foundations so that they can span over the well, far enough so that any future subsidence of the ground adjacent to the well will not affect the foundations or the building.

This type of problem is often only discovered when the excavation for the foundations starts. Therefore a quick solution is required.

Our designs normally result in only a very small increase in the construction cost.

We need the following information to design this type of foundation:

architectural layouts or sketch drawings with dimensions of the building / extension showing the position of the main walls in relation to the well

The location, diameter and depth of the well

Design information

All designs are carried out in accordance with BS 8110 (The structural use of concrete) and BS 8004:1986 (The code of practice for foundations).

You should satisfy yourself that the excavation for the foundations will not undermine any adjacent foundations or neighbouring ground

Excavations may fall under the Party Wall Act Please seek specialist advice. click for party wall act information