Things were getting serious, we had a rough idea of what we were building, and we were ready for the next stage. This meant looking into our land, sizing it up and making sure it was suitable for what we had in mind.
Metricon engaged the services of an external engineering company who sent out a surveyor to measure up our block, define the contours and mark key features, such as utilities and the party walls of our neighbours.
As we embarked on this project, we always knew there would be some challenges with the party walls given that the original house appeared to be constructed as a group of semi-detached dwellings that were built for the Housing Trust sometime back in the 1970’s. Later that week the company sent someone to carry out soil testing.
This person ended up driving several coring tubes a few metres deep and several locations around the property. He then set up a tripod stand and a chain block to extract the tubes which contained the soil samples. These were then laid out on a cardboard tray for his analysis.
Several weeks later we received an engineering report containing:
- Site Classification – Based on Soil Reports
- Footing Recommendations
- Design Wind Speed
- Bushfire Risk Level
- Corrosion Assessment
- Survey Drawing
- Proposed Footing Design
- Stormwater Calculations and Rainwater Tank design
- Preliminary Framing Layout
We were relatively lucky with our soil type, as we were building in sandy soil which typically promotes good drainage. It is worth noting that when soil samples were taken on our property, a considerable amount of building rubble was found in one location. As a result, the engineer wanted to increase the number of piers in the concrete footing. This conservative approach is understandable given that the slab is essentially warranted for life by the engineer. However, it did add an unbudgeted amount to the build cost. Where reactive soil is present, or risk of ground movement is high (e.g., clay soils with poor drainage), the footing cost can be many times higher.
As our house was considered within the corrosion zone, additional costs were added to account for this. What practical measures that are to be implemented remain to be seen.