The scope of a condition investigation, and what the report should contain

A free quotation and a condition investigation are different products, and the distinction is frequently the most consequential one in remedial procurement. A quotation scoped from a walk-around is priced against conditions the contractor has not established, which produces either a contingency loading or exposure to variations. A condition investigation replaces that uncertainty with tested evidence before either party commits to a figure.

This article sets out what a condition investigation comprises and what the resulting report should contain.

Desktop review

The investigation begins before site attendance. Available drawings, previous condition or engineering reports, maintenance history, and the record of defect complaints mapped by location and date are reviewed.

That record is frequently the most informative document available. Recurring leak reports concentrated on one stack, or a sequence of complaints following particular weather conditions, indicate where the mechanism is likely to be found and inform which tests are worth carrying out.

Systematic visual survey

Every accessible element is surveyed, not only the element that generated the complaint. Defects are photographed, located and assigned a reference within a numbered schedule.

The schedule is the document that makes the eventual scope both priceable and comparable between contractors. Without it, quantities cannot be established and competing quotations price different assumptions.

Test methods selected by mechanism

Testing is selected according to the mechanism suspected from the survey, rather than applied as a standard package.

Test method	What it establishes
Tap or hammer survey	Extent of drummy render, tiles and concrete delamination
Cover meter survey	Reinforcement depth and position, the primary predictor of corrosion risk
Carbonation depth testing	The depth to which the alkaline protection of the concrete has been lost
Chloride sampling	Whether conventional patch repair can arrest corrosion, or whether a protection system is required
Half-cell potential mapping	Zones of active corrosion not yet apparent at the surface
Moisture mapping and electronic leak detection	The extent of the wet footprint and the location of the entry point
Anchorage pull testing	Whether balustrades, anchors and fixings achieve their design loads
Investigation openings	The condition of concealed substrates, screeds and membranes

Investigation openings

Some of the most significant evidence requires lifting tiles or breaking out small areas. The appropriate approach is representative sampling: sufficient locations to establish the pattern across the building, reinstated on completion, with the number and location agreed in advance and priced within the investigation fee.

An investigation that omits openings on a building with concealed membranes and screeds has established the surface condition only, and the scope that follows carries the same uncertainty as one prepared without any investigation.

Contents of the condition report

A condition report should contain:

• A defect schedule with locations, references and photographs
• Cause analysis identifying the mechanism rather than describing the symptom
• Extent mapping, including deterioration established by testing that is not yet visible
• Repair options at more than one level of intervention, with the trade-offs of each stated
• Risk ranking, distinguishing items requiring immediate attention from those suitable for programming
• Budget guidance for each option

A report that concludes with a single figure and no defect schedule is a quotation. It may be an accurate quotation, but it does not provide the evidence required to compare it against another, or to fund the works through a resolution that will be scrutinised.

Cost of proceeding without investigation

An investigation is typically a low single-digit percentage of the value of the works it defines. The costs it displaces are as follows.

Variation exposure. Scope discovered during the works is priced at variation rates, at a point when access has been erected and finishes removed, and when suspending the works to obtain competing prices carries its own cost.

Repairs that do not arrest the mechanism. Patch repair applied to chloride-contaminated concrete relocates the corrosion cell to the perimeter of the repair. A membrane installed over unresolved structural movement or inadequate falls fails in the same manner as the membrane it replaced. Both outcomes require the work to be funded a second time.

Funding credibility. An owners corporation that has levied for works subsequently found to be inadequately scoped will encounter greater difficulty obtaining support for the second resolution than it did for the first.

General information, not advice on a specific building. Investigation scopes vary with the structure, its age and the symptoms reported.