2025 Survey Costs (ex VAT)
| Property | Standard | Fast Track (+25%) | Rush (+50%) | | --- | --- | --- | --- | | 2–3 bed | £400–£600 | £500–£750 | £600–£900 | | 4+ bed | £500–£800 | £625–£1,000 | £750–£1,200 | | Commercial | £800–£1,500 | £1,000–£1,875 | £1,200–£2,250 |
Survey Deliverables Reference
| Deliverable | Format | Use | | --- | --- | --- | | Floor plans | DWG + PDF | Design reference | | Elevations | DWG + PDF | Planning submission | | Sections | DWG + PDF | Building regulations | | Site plan | DWG + PDF | Planning boundary |
When to Start Structural Monitoring: Before During or After Excavation?
One of the most important decisions in a monitoring programme is timing. When should monitoring begin? Before excavation, during excavation, or after? The answer affects the quality of monitoring data and the protection it provides.
This article explains when to start structural monitoring and why timing matters.
The Short Answer
Start structural monitoring before excavation begins. The baseline survey — the recording of conditions before construction — must be completed before any works that might cause movement. Without a baseline, you cannot demonstrate that any movement occurred during construction rather than before it.
Starting monitoring after excavation has begun means the opportunity for an accurate baseline is lost. Any movement observed after monitoring begins may have occurred before monitoring started. This creates ambiguity and risk.
Why Before Excavation?
Monitoring must begin before excavation for several reasons:
Baseline Accuracy
The baseline survey establishes the reference point for all subsequent measurements. It documents the condition of structures before any ground disturbance occurs.
If excavation begins before the baseline survey, the baseline records conditions that may already include some movement caused by early works — preparatory demolition, enabling works, or even the commencement of excavation. This makes it impossible to attribute subsequent movement accurately.
A proper baseline survey records conditions before any works begin. This gives the clearest possible reference point for monitoring.
Legal and Contractual Requirements
Party wall awards, lender requirements, and insurance conditions typically require monitoring to begin before construction commences. Starting monitoring after works have begun may not satisfy these requirements.
Party wall awards specifically require a schedule of condition and baseline monitoring of the adjoining owner's property before works begin. If works have already commenced, the adjoining owner may have grounds to object.
Evidence Quality
Monitoring data is evidence. If damage disputes arise, the quality of the evidence matters. A baseline survey conducted before works provides clear evidence of pre-existing conditions. A baseline survey conducted after works have begun provides ambiguous evidence.
The stronger your baseline evidence, the better protected you are if disputes arise.
What About Starting During Excavation?
Starting monitoring during excavation is not ideal but may be acceptable in some circumstances:
Retrospective monitoring: If monitoring was not commissioned at the outset, starting during excavation may be better than not monitoring at all. A partial baseline is better than no baseline.
New structures: If monitoring is for the structure being constructed rather than adjacent structures, starting during construction may be acceptable. Floor level monitoring during a basement build, for example.
Late commission: If monitoring is commissioned partway through a project, starting during works captures what data it can, even if the baseline is incomplete.
However, starting during excavation should always be a fallback, not the plan. Commission monitoring before works begin whenever possible.
What About Starting After Excavation?
Starting monitoring after excavation is generally not acceptable for protecting adjacent structures. By the time excavation is complete, the highest-risk period has passed. Any movement that occurred during excavation has already happened.
Post-excavation monitoring can confirm that conditions are stable after excavation is complete. It cannot capture the movement that occurred during excavation.
If monitoring is required for post-construction condition tracking or for lender requirements after construction is complete, post-excavation monitoring is appropriate. But it does not replace pre-excavation baseline monitoring.
The Baseline Survey Timeline
A typical monitoring timeline for an excavation project:
4 to 8 weeks before excavation: Commission the monitoring surveyor. Provide project details, construction programme, and monitoring requirements.
2 to 1 weeks before excavation: Baseline survey is conducted. All structures to be monitored are surveyed. Monitoring points are installed. Baseline report is issued and distributed.
Before first excavation: Baseline report is received and reviewed. All stakeholders confirm monitoring programme is in place.
During excavation: Monitoring visits at appropriate frequency. Reports issued. Alert protocol activated as needed.
Post-excavation: Monitoring continues at reduced frequency. Post-completion monitoring confirms stability.
Minimum Baseline Requirements
If monitoring must start during or after excavation due to late commission, the minimum baseline requirements are:
Photographic record: Comprehensive photographs of all elevations and significant features. Photographs should be taken from positions that show the relationship to the construction site.
Crack mapping: All visible cracks should be measured and located. This establishes what cracking existed before monitoring began.
Level data: Level measurements at monitoring points, referenced to stable benchmarks. Even if excavation has started, benchmarks outside the zone of influence provide valid reference data.
Documentation: The baseline should clearly note that it was conducted after some works had begun. This establishes the context for interpreting subsequent data.
Commissioning Monitoring Early
The best way to ensure monitoring starts before excavation is to commission it early:
At project inception: Identify monitoring requirements when the project is first conceived. Include monitoring in the project budget and programme.
Before contractor appointment: Commission the monitoring surveyor before the main contractor is appointed. This ensures monitoring is in place from the start.
Before any site works: Ensure the monitoring surveyor has access to all structures before any preparatory works begin.
Early commissioning protects the project and provides the best quality monitoring data.
Monitoring Frequency and Excavation Phases
Monitoring frequency should be highest during the highest-risk excavation phases:
Pre-excavation: No monitoring visits — baseline is established, monitoring points are installed.
Initial excavation: Weekly or twice-weekly monitoring. Ground is being disturbed and structures are most vulnerable.
Deep excavation: Weekly monitoring. Risk is highest during deep excavation near existing foundations.
Below ground construction: Reduced frequency — fortnightly — as the structure becomes more complete.
Post-excavation: Monthly monitoring to confirm stability.
Fixed-Fee Monitoring from icelabz
icelabz provides fixed-fee structural monitoring surveys. We commission monitoring programmes before construction begins to ensure proper baseline surveys are conducted.
Contact icelabz with your project programme for a fixed-fee monitoring quote.
Party Wall Award Requirements
Party wall awards typically require monitoring to begin before any works affecting the party wall commence. This includes excavation below the level of the adjoining owner's foundations.
The award specifies the monitoring requirements, which typically include a schedule of condition of the adjoining owner's property and baseline monitoring before works begin.
Starting monitoring after works have commenced may not satisfy party wall award requirements. The adjoining owner or their surveyor may object.
icelabz works with party wall surveyors to ensure monitoring programmes satisfy award requirements.
Lender Monitoring Requirements
Lenders often require monitoring as a condition of lending. Requirements typically specify:
- Monitoring must begin before construction commences
- Baseline survey must be completed and distributed
- Regular monitoring reports must be submitted during construction
- Final monitoring report must be provided before final drawdown
Starting monitoring after works have commenced may not satisfy lender requirements. Confirm requirements with your lender before commencing works.
Structural Engineer Recommendations
Structural engineers typically recommend that monitoring begin before excavation. The structural engineer advises on monitoring methods, trigger levels, and frequency based on the construction method and ground conditions.
Follow the structural engineer's recommendations on monitoring timing. Their expertise informs the monitoring specification.
Cost Implications of Late Commissioning
Commissioning monitoring late has cost implications:
Partial baseline: A baseline survey conducted after works have begun may be less comprehensive than a pre-works baseline. Additional surveys may be needed to fill gaps.
Additional visits: If monitoring starts late, additional visits may be needed to establish a reliable reference point.
Programme risk: Late commissioning creates programme risk. If monitoring is required before works can proceed, delay in commissioning monitoring delays works.
Commission monitoring early to avoid additional costs and programme risk.
Fixed-Fee Monitoring from icelabz
icelabz provides fixed-fee structural monitoring surveys. Monitoring programmes are commissioned early to ensure baseline surveys are conducted before works begin.
Contact icelabz with your project programme for a fixed-fee monitoring quote.