Design says one metre, the ground says otherwise
Plot foundations are designed to a depth, but the ground decides. Tree roots, soft spots and made ground mean some trenches go deeper, sometimes much deeper, before the inspector is happy. Your gang digs until they reach a suitable bearing, the building control or warranty inspector looks and agrees, and the trench is filled. The extra dig and extra concrete are real costs.
When your QS claims for the extra, the housebuilder asks for the depths. The ganger remembers roughly. The inspector's visit was a chat in the trench.
Why depths are not recorded
The gang digs to the depth the ground requires, and the only record that seems to matter at the time is the inspector's approval. Depth measurements are taken to know when to stop, not to write down. Concrete dockets are for the pour, not the plot. So the facts that support payment are never put together.
- Depths are measured but not recorded per plot.
- Inspections are verbal and not logged against the plot.
- Concrete volumes are not tied to the plot they went into.
- Design depths and actual depths are never compared.
- The extra over design is worked out at month end from memory.
What unrecorded depths cost
Extra excavation, muck-away and concrete you paid for but cannot prove. Arguments with the housebuilder about deeper foundations on plots long since built on. Estimates for the next site that cannot learn from this one, because nobody knows how often or by how much trenches went deeper. And no easy way to answer questions later about what is under a particular house.
Foundation records we build
- Each plot is loaded with its foundation layout and design depth from the engineer's drawings.
- As the trench is dug, the ganger records depths at set points on a phone, each with a photo showing the staff or tape in the trench.
- The reason for going deeper is recorded where it applies, such as roots, soft spot or made ground.
- The building control or warranty inspection is logged against the plot: date, inspector, outcome, and any note of the agreed depth.
- Concrete dockets for the pour are linked to the plot, so actual volume is recorded next to the design volume.
- The extra depth and concrete over design are calculated per plot and priced at your agreed rates for your QS to check.
- The record is kept with the plot, and can be shared with the housebuilder and engineer.
| Plot | Design depth | Actual depth | Reason | Inspection |
|---|---|---|---|---|
| 12 | To design | As design | None | Passed |
| 13 | To design | Deeper | Tree roots | Passed at depth |
| 14 | To design | Deeper | Soft spot, rear wall | Passed at depth |
| 15 | To design | As design | None | Awaiting visit |
Foundation design and what depth is acceptable are for the engineer and the inspector. We record what was dug and agreed; we do not advise on foundations.
Depths you can stand behind
Every plot has a record of how deep the foundations went, why, and who agreed it, with photos. Extra dig and concrete are priced from facts, and the housebuilder's QS can check them. You can see across a site, and across sites, how often trenches go deeper, which improves the next price. And if anyone asks later what is under a particular house, the answer is on file.
Are your foundation depths recorded like this?
- Actual depths are not recorded per plot.
- Inspections are not logged against plots.
- Concrete is not tied to the plot it went into.
- Claims for deeper foundations are disputed.
- You price new sites without knowing how often trenches went deeper.