Material Condition & Properties

Depths of Cover to Reinforcement:- Covermeter survey in accordance with BS1881

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

In-situ Testing for Depths of Carbonation:- Using phenolphthalein indicator solution in accordance with BS EN 14630:2006

Chemical Screening:- Representative samples, prepared in accordance with Section 4.1 of BS EN 14629: 2007, would be submitted to a UKAS Accredited Laboratory for analysis for the contents of aggressive agents, e.g. chloride ion, sulphate, alkali-metals and other, cast-in or ingressed, contaminants.

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

Rebound Hammer Testing:- In cases where the preparation of core samples and direct testing for strength is not practicable exposed concrete surfaces can be prepared and tested for rebound number in general accordance with BS EN 12504.

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

Concrete elements to be tested should be at least 100mm thick and fixed within a structure, with areas exhibiting honeycombing, scaling, rough texture, or high porosity avoided.

Smooth-formed or trowelled surfaces may be tested ‘as-is’, but heavily textured surfaces, soft surfaces, or surfaces with loose mortar should be prepared by grinding back to a sound substrate, using an abrasive stone, or other similar means.

Testing will be carried out in accordance with the above referenced standard procedure, paying particular attention to the operation of the ‘hammer’, the number and proximity of individual readings per set of readings, the inspection of any impressions made on the surfaces by each test and the use of the reference block or anvil.

Results will be presented and reported as required by the above referenced standard procedures.

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

Screed Testing:- Using a BRE Screed Tester (Drop Hammer):- A test developed by the Building Research Establishment in the 1970’s and now included in BS8204 for Screeds, bases and in-situ floorings. The test measures the ‘soundness’ or ‘in-situ crushing resistance’.

However, as renders, plasters and screeds are generally ‘thin’ layers, sounding or hammer testing needs to be undertaken carefully, with this in mind. The hammer should be drawn across the surfaces and used lightly to tap them, to resolve the shallower delaminations likely.

NB: The test methodology varies depending upon the type of screed.

Visual Inspection:- As far as practicable, a full close-quarters visual inspection following the procedure described within our Documented In-house Procedure CRLS STP01.

However, our attention will be addressed towards the presence of any additional features, which could be consistent with the corrosion of any metal components within the brickwork elements, as described within documents such as BRE IP 28/79, BRE IP 12/90, BRE IP 13/90 and BRE Digest 461.

NB: During the following intrusive investigations our intensions will be to maximise the information gathered, whilst minimising the extent of disruptive and damaging intrusion.

Wall Tie Detection / Distribution Survey:- Brickwork / masonry surfaces, within selected test areas, will be subjected to scanning using either a Protovale Limited “Imp” wall tie detector, fitted with an appropriate detector-head, or covermeter surveying using a Hilti Limited, “Ferroscan”, or other similar instrument, in accordance with the manufacturer’s instructions and in general accordance with British Standard BS1881.

The distribution of the wall ties will be assessed for comparisons with the requirements of BS 5628.

NB: Ties have been available in a wide range of types, manufactured in a wide range of materials, including plastic / nylon etc., mild steel / galvanized mild-steel, alloy steels and stainless steel. The above instruments, other than the “Imp”, fitted with an appropriate detector-head, will be inappropriate for the detection of ties, other than those manufactured from mild-steel / galvanized mild-steel.

Furthermore, even where ties were manufactured from mild-steel / galvanized mild-steel detection limits, with respect to both depth and accurate positioning, vary significantly from instrument to instrument and generally, in our experience, resolutions deteriorate significantly with depths greater than around 100mm. Furthermore, in some cases, contamination of the substrate material with magnetic constituents can result in erroneous responses which can be, at best, difficult and misleading to resolve

Remote Inspection of wall Ties (borescope / endoscope investigation of cavities):- A selection of the ties identified above will be investigated, in order to evaluate, as far as practicable, their generic type, condition and fixity (i.e. were they installed adequately ‘front’ and ‘back’), together with an inspection of the cavity, for form and condition, using fibre-optical borescopes / endoscopes, inserted through small drilled holes.

NB: Low or poor lighting within the cavities and the limited fields of view, together with contamination of the cavities with brick / masonry rubble and / or excess mortar will collectively limit the resolution of the ties.

Direct Inspection of Wall Ties (brick / block removal):- In cases where remote inspections cannot satisfactorily resolve the type, condition and fixity of any ties, or where further investigations of the cavities are considered appropriate, individual bricks or blocks will be removed, using small hand-held tools.

Brick Compressive Strength:- Brick specimens, 10No. per ‘set’, will be submitted to a UKAS Accredited Laboratory for testing in general accordance with BS3921.

Bedding Mortar Analysis:- Samples will be submitted to a UKAS Accredited Laboratory for preparation and chemical analysis, for the calculation of mortar mix proportions, in general accordance with BS 4551.

Having assessed the likely mortar mix proportions, the mortar designation, as described within BS 5628 can be estimated, as indicated within Part 1, Table 1 (page 7), together with the possible approximate compressive strength.

We offer a ‘one-stop-shop’ for the inspection, survey, investigation and testing of all components of buildings and structures and although we do not specialise in assessing metals we can, in cooperation with recognised, UKAS Accredited specialists, prepare the samples required for Laboratory analysis and testing. For example samples of iron can be prepared for microscopical analysis of composition, uniformity and presence of contaminants and other inclusions, together with testing (‘nick’ and ‘spark’) for assessing the differences between cast iron, wrought iron and mild steel. Both iron and steel samples can be tested for hardness and tensile strength, including residual tensile strength following exposure to fire.

The method of sampling and the size of the specimens will be governed by the type of analysis and testing required. However, as far as practicable, sampling will be undertaken as carefully as possible, from unobtrusive locations and without causing unnecessary damage.

In many cases it will be more cost effective and efficient to employ our expertise whilst we are on site, as opposed to the costs involved with the additional mobilisation of a Team from a Laboratory.

Although membranes and coatings can be considered as ‘simply’ waterproofing or cosmetic they should also be considered as affording the substrate a greater degree of protection, than aesthetic improvement. They are the first line of defence against the ravages of environmental exposure and when up to the job, in good condition and intact they will maintain the substrate in a sheltered, ‘mild’ and passive environment for many years.

However, membranes and coatings can be supplied with a wide variety of formulations and ranging from non-flexible, to flexible and ultimately elastomeric, with applications suitable for roofing, decking, general surfaces and some specialist applications resistant to chemical attack. Some coatings will be non-crack bridging and others specified with variable crack bridging properties and due regard should be addressed towards these properties, and the potential need for over-banding, or the provision of formal joints and / or seals, as splits within the coatings will be the ‘weak link in the chain’.

We can offer an upfront advisory service with respect to ‘new’ coatings, specifications and proposed applications and a forensic service in circumstances where ‘old’ coatings have reached the end of their designed life and the surfaces are in need of re-coating, or in cases where coatings have failed.

We are UKAS Accredited for undertaking tensile bond / adhesion (pull-off) testing in accordance with BS 1881, BS 3900-E10 BS EN ISO 4624.

We offer a ‘one-stop-shop’ for the inspection, survey, investigation and testing of all components of buildings and structures and although we do not specialise in assessing architectural detailing we can, in cooperation with recognised specialists, undertake the inspection, survey and investigation of such details and where required prepare samples for testing by UKAS Accredited laboratories.

In many cases it will be more cost effective and efficient to employ our expertise whilst we are on site, as opposed to the costs involved with the additional mobilisation of a Team from a Laboratory.

The full and thorough Inspection, Survey and Investigation of buildings and structures, particularly where maintenance, repair, alteration or strengthening may be required is a multi-disciplined process which should include all building components.

CRL Surveys can offer a ‘one-stop-shop’ including:

Assessments of windows for type, operation and remedial works required, together with the glazing for breakages and fracture analysis.

Assessments of drainage goods, in terms of completeness, functionality and blockages, including CCTV surveys (by recognised specialists).

Assessments of over-cladding systems, for fire resistance testing (by recognised specialists) and compliance with specification (in terms of fixing and make-up).

Roofing, for make-up and functionality.

Timber, for make-up, damp and rot.