Delay Substantiation for Construction Scheduling

A delay substantiation is a central instrument in everyday construction and deconstruction practice to objectively record schedule deviations, make causes transparent, and demonstrably trace impacts on schedules. Especially in projects involving concrete demolition, interior demolition, or rock excavation, where methods such as splitting, cutting, or shear operations are used, robust documentation helps to assess disruptions to the construction process in a structured way. If, for example, an unexpectedly high reinforcement density is encountered when working with concrete demolition shear, or if hydraulic rock and concrete splitters require additional drilling, the resulting time requirement can only be represented plausibly and fairly through a properly maintained delay substantiation.

Definition: What is meant by delay substantiation

Delay substantiation is an orderly, timely, and auditable compilation of information that evidences the occurrence of a delay, its cause, responsibility, and time consequence. It differs from an informal note in that it establishes the causality between an event and its effect on the construction schedule in a traceable way. In practice, this includes a description of the event (location, time, affected section), the technical classification (e.g., material properties, accessibility, constraints), the affected resources (personnel, equipment such as concrete demolition shear, hydraulic power pack, or rock wedge splitter), as well as an assessment of the schedule consequences. The applicable formal requirements depend on the respective contract and relevant standards; a prompt notice and ongoing updates of the impacts in the schedule are common.

Structure and contents of a robust delay substantiation

An effective delay substantiation is clearly structured, uses consistent data sources, and maintains a factual tone. It should be set up so that third parties can follow the derivation of the time impacts without additional knowledge.

Core components

Event description: date, time, location, section, affected structural elements.
Cause and boundary conditions: technical impediments, constraints, missing preceding work.
Resource reference: deployed or blocked personnel and equipment (e.g., concrete demolition shear, hydraulic splitter, hydraulic power packs, combination shears, steel shears, tank cutters).
Performance deviation: productivity before/after the event, missed cycles, downtimes.
Countermeasures: re-planning, substitute methods, partial implementations.
Time impact: affected activities, critical path, need for extension of time.
Evidence: daily site reports, photos and sketches, measurement and test records, delivery notes, weighbridge tickets, approvals/protocols.

Form and traceability

Complete site diaries, structured time and equipment logs, and a schedule that documents changes in an audit-proof manner have proven effective. The more consistent the sources (timestamps, measured values, protocols), the more robust the substantiation.

Typical causes of delays in concrete demolition and special demolition

In deconstruction, planning specifications meet as-built reality. This leads to recurring patterns of causes that must be precisely identified in the delay substantiation.

Unexpected material properties: high-strength concrete, above-average reinforcement, composite elements.
Restrictions on site: tight access, work in confined stories, limited load-bearing capacities.
Constraints on noise, vibration, dust, or utilities: altered working windows, additional protective measures.
Utilities and embedded components: undocumented cables, pipes, inserts, tanks, and contaminated components.
Approvals and permits: waiting times for clearance measurements, structural approvals, H&S coordination.
Logistics and disposal: bottlenecks in containers, haulage, and receiving facilities.
Weather and safety: moisture, frost, heat protection, emergency shutdowns for occupational safety reasons.

In all these situations, takt and methods change: concrete demolition shear require additional cutting cycles with dense reinforcement, hydraulic splitter require more drill holes in tough rock structures, and tank cutters only work after documented gas-free status. These additional times must be substantiated objectively.

Causality and delineation: internal vs. external influence

For the assessment it is essential whether the delay lies within one’s own area of responsibility or was caused externally. The delay substantiation sets out the chain from event to cause, effect, and time consequence. It also delineates simultaneously occurring influences so that no impermissible overlap arises.

Proof of equipment availability

Anyone claiming delays documents the readiness of the intended technology. This includes maintenance records, test protocols, and operating times of hydraulic power packs, shears, and splitting cylinders. If, for example, a hydraulic power pack was available but clearance for the work area was missing, the downtime can be causally assigned to the external factor.

Method selection and delay substantiation: splitting, cutting, shears

The choice of method is often made during work preparation. When as-built conditions force deviations, performance values and work cycles change. The delay substantiation describes the adaptation factually: switching from cutting to splitting, changing grippers or jaws on concrete demolition shear, additional drilling effort for hydraulic splitter, or intermediate steps with steel shears.

Illustrative scenarios from practice

Interior demolition and cutting: undocumented cable routes require securing and separation work with Multi Cutters before the actual shear operation. Time required for isolation and marking is logged.
Concrete demolition: high-strength concrete with dense reinforcement reduces the cutting speed of the concrete demolition shear. To minimize vibration, work is additionally performed with hydraulic splitter. Extra cycles and drilling times are recorded.
Special tank operations: tank cutters may only work after documented gas-free status and clearance. Waiting times for measurement logs and ventilation phases are included in the substantiation.
Rock excavation and tunnel construction: unexpected joint systems require different rock wedge splitter or altered drilling patterns. Adjustments and their impacts on the advance are evidenced.

Time impacts and assessment: from hindrance to extension of time

An event becomes a defensible time entitlement only when its consequences are located in the schedule. Methodical analyses that present the difference between the baseline and the updated schedule and show the impacts on the critical path are standard. The basis is realistic performance values of the methods used.

Performance indicators as a basis

Cycle times and takt: cutting and crushing cycles with concrete demolition shear, splitting cycles and drilling performance with hydraulic splitter.
Setup and relocation times: jaw changes, hose and power pack relocations, establishment of work areas.
Material flow: feeding, intermediate storage, haulage, and disposal logistics.
Requirement-driven pauses: noise windows, dust suppression, safety briefings, and approvals.

Documentation: evidentiary security and readability

Documents must be understandable and depict the project progress without contradiction. Timely capture increases credibility and reduces room for interpretation. Clear, non-judgmental language supports verifiability.

Good practice

Immediate, objective notice of hindrance with key data (who, what, when, where, why, how long).
Coordination and minutes in site meetings with clear measures and responsibilities.
Photos, videos, and sketches with date/time and reference to the construction section.
Measurement and test records (e.g., material tests, clearance measurements, rebar scans).
Equipment and labor hours per activity, separated by trades and sections.

Interfaces to quality, occupational safety and environment

Quality and protective measures are often causes of delay, yet technically necessary. Examples include dust and noise protection, vibration limitation, gas clearance measurements, or changes to load cases. The delay substantiation documents that requirements were observed and that the resulting time portions are duly accounted for. For instance, the use of low-vibration methods (e.g., splitting instead of impact) is explained when vibration limits must be adhered to in sensitive areas.

Delay substantiation in contracts and codes

The deadlines, forms, and review criteria are defined by the contract and applicable rules. Common practice is prompt notification, a clear presentation of causality, and an auditable quantification of schedule impacts. Project-specific agreements and regulatory requirements take precedence; the delay substantiation reflects these framework conditions without replacing them.

Practical checklist for day-to-day project work

The following steps support a consistent, verifiable approach in daily operations.

Capture the event immediately: key data, location, section, parties involved, initial assessment of the cause.
Verify the cause: technical review, approvals, constraints, as-built reconciliation.
Quantify the impacts: affected activities, cycles, performance values, critical path.
Document communications: notice, feedback, meeting minutes, instructions.
Initiate countermeasures: adapt methods (e.g., switching between shears, splitting, cutting), allocate resources.
Update the schedule: revision with clear assumptions and data dates.
Archive evidence: photos, protocols, time and equipment logs, disposal records.

Reference to devices and application areas of Darda GmbH

Delay substantiation gains in evidentiary force when it considers the specifics of the methods and devices used. In the application areas of concrete demolition and special demolition, interior demolition and cutting, rock excavation and tunnel construction, natural stone extraction, and special operations, the methodological fit plays a central role—and with it the documentation of the resulting performance values and boundary conditions.

hydraulic splitter: evidence of drilling performance, splitting cycles, wedge use, and adaptations of the drilling grid; influences due to rock or concrete strength and constraints on vibration limitation.
concrete demolition shear: recording of cutting/press cycles, jaw changes, and effects of reinforcement density; hydraulic requirements (flow rate, pressure) and their availability via hydraulic power packs.
Hydraulic power packs: documentation of setup times, supply routes, hose lengths, operating windows, and noise protection requirements.
Combination shears, Multi Cutters, and steel shears: description of varying material thicknesses, cross-sections, and necessary intermediate cuts; influence on takt and safety.
Rock wedge splitter: coordination with bore diameters, setting sequences, and deconstruction stages; evidence of adaptation to local geology.
Tank cutters: required approvals, ventilation and measurement times, safety distances; precise logging of clearance measurements before work begins.

By mapping these method-specific aspects precisely, delay substantiation provides a robust basis for the objective evaluation of time impacts—regardless of whether a project predominantly involves cutting, splitting, or shear operations.