Assessments of Dilapidations & Defects

The Extents of Dilapidations, Defects and Remedial Works Required In many cases, an important part of our work is to evaluate requirements for remedial works in terms of the quantities of repair required.  The following procedures are used as a means of identifying and scheduling these requirements, obviously undertaken by suitably trained and experienced Technicians: Visual Inspection:- We undertake, as far as practicable, a full close-quarters visual inspection following the procedure described within our Documented In-house Procedure CRLS STP01.

This procedure is covered by CRL Surveys UKAS Accreditation, UKAS Ref:  2728. For further details please visit www.ukas.com

Sounding or Hammer Testing:- Concrete surfaces will, as far as practicable be subjected fully to light sounding using a “lump hammer” following the procedure described within our Documented In-house Procedure CRLS STP02.

This procedure is covered by CRL Surveys UKAS Accreditation, UKAS Ref:  2728. For further details please visit www.ukas.com

A “lump hammer” should be drawn over the concrete surfaces or used lightly to tap the surfaces.  However, although a ‘simple’ test, it is extremely useful, but easily flawed by poor practice and Operatives should therefore consider:-

  1. Thin structures / elements, such as pre-cast cladding panels and parts thereof, which may inherently sound ‘hollow’, and should be tested accordingly. Is the hollowness identified a detail of the panel make-up, rather than damage or distress (also consider 4, below)?
  2. Drawing a hammer across or over surfaces will highlight relatively ‘shallow’ delamination / surface skims, with the latter either de-bonded or masking / hiding ‘faults’, which should be explored and resolved.
  3. ‘Heavier’ tapping or hammering may not resolve ‘shallow’ hollowness, but will resolve ‘deeper’ hollowness, but consider 1, above.
  4. Excessive tapping or hammering may cause unnecessary damage, particularly to exposed aggregate surfaces, thin finishes and edges, e.g. the edges of some pre-cast panels were cast with recesses to accept baffle / sealing strips.

Exploratory Breaking Out (concrete only):- The reinforcement at selected, representative existing spalled locations will be chased back into sound concrete.  Exposed and corroded reinforcement will be further exposed in order to assess both the extent of corrosion, in relation to the depth of carbonation and depth of chloride contamination at that location, but also to determine reinforcement bar type/s, which would be identified using the classifications described within CIRIA Special Publication 118.  Reinforcement bar diameters and, if applicable, any loss of cross-section will be recorded.

In addition, for guidance, the relative dimensions and form, of potential repairs, compared to the visual defects, will be assessed, to provide, as far as practicable, data for the subsequent preparation of concrete repair bills of quantity, as described within the Concrete Repair Association (CRA), Standard Method of Measurement and Concrete Society Technical Report No.38.

In some locations, the reinforcement within selected sound areas, at progressively greater depths of cover, may be exposed and inspected for evidence of deterioration and corrosion in order to assess the likely depth at which the reinforcement is potentially at risk from deterioration and corrosion.

NB:  In the case of pre-cast cladding panels, and potentially other forms of construction, an assessment of Form and Fixing may be advisable, or even necessary.  Deterioration and distress may focus around particular areas of constructional detail, such as fixings, which should be resolved in order to assess reparability.