TECHNICAL DATA SHEET 1.1
This method stabilises existing wall foundations by digging under the present foundation in sequenced bays to a depth where firm strata exists and replacing the excavated material with mass concrete.
The loading capabilities are based upon the strata encountered. In some circumstances when the existing footing is adequate to span between supports, intermediate piers can be used to reduce cost, i.e missing out piers 2 and 4 as shown on the diagram below. A suitable bearing stratum is assessed by the Supervising Officer or Building Inspector upon completion of the first sequence of bays.
Traditional Underpinning is usually applied when the existing foundations are at shallow depth.
Bays are excavated generally 1.0m – 1.2m in length, 0.6m wide, and up to 2.5m from ground level. However a minipiled solution would be more economical over depths of 1.5m.
Advantages of this system are:
Simple engineering and easily understood.
Suitable for heavy loads and massive structures.
Occupants can remain in the propertyas work can be undertaken from outside.
Method can be used in restricted access areas.
Suitable for formation of new cellars and basements.
Low cost solution at shallow depths.
Minimal disruption and noise generated.