Video and Endoscopic Photography Survey

Boroscope inspections, what they can do for you and how they can protect you – with photography

Boroscopes have been in use for a number of years. However, they take some getting used to and it’s not surprising that some customers find it hard to comprehend what the surveyor is describing in his report. This can be especially disconcerting, if a customer is potentially facing an expense for remedial work, yet to the naked eye there appears to be nothing wrong with a building – the client is relying on the surveyor’s integrity and expertise.

Bryan Hindle – our managing director, wrestled with this issue until 2002, when he researched an effective way of using endoscopic photography – obtaining digital images through the boroscope, so you can see what we see and get a much better understanding of your report.

This groundbreaking method is particularly useful for wall tie corrosion inspections, tie orientation and embedment inspections too. Property buyers find it invaluable when they are faced with convincing a sceptical vendor that there really is a hidden defect, which needs repairing. Conversely, vendors have found it useful in showing that there is no defect at all, when perhaps a buyer or another specialist firm had implied the opposite.

Corrosion isn’t the only field this helps with: recent survey projects include helping a well know house builder prove that the wall ties in his freshly completed development met embedment and orientation requirements. The need for this followed a ‘one-off’ error by one of our clients’ sub-contractors, which initially threw doubt on the whole project – we were able to help.

We take these images whenever we can, for our survey needs, quality control and for fun too; there are thousands in our databank. We can edit and add your site photos into the written report for a small processing fee – just ask.

Architects, engineers and surveyors use us extensively, because they value evidence above opinion.

We also use digital photography daily; recording the tension test results our technicians get when working on wall tie and lateral restraint contracts. We understand that our clients trust us – but verification, by testing and recording ensures that their trust is never misplaced.

“The following is a short guide on the world of wall tie corrosion – seen through Bryan’s boroscope…and photographed for you”

Even relatively new galvanised ties may exhibit slight corrosion. This is from an inspection on a house built in the 1980’s. Notice the very shiny and sound surface, with slightly dull zinc in places and very early stage zinc oxide deposits (white patches). This is no cause for concern.

This is the other end of the corrosion scale. A very heavily corroded fishtail tie inspected and photographed by Bryan at a pre war property. This corrosion has been accelerated by the lack of any galvanising in the first place and corrosive black ash mortar, used in the construction. Notice the very rough under surface, caused by lamination of the ferric oxide.

Galvanised ties corrode to this extent, even without the assistance of black ash mortar. A sure sign of poor galvanising application, note that the sound zinc (top of image), gradually decays; first to zinc oxide (white deposits) and then on to real red rust (ferric oxide). This is a severe and urgent issue. It is not just a case of the tie losing strength; the corrosion breaks the intimate bond between the mortar and the tie. In effect, failure can occur whilst the tie is still relatively strong – the outer skin just pulls away from the ties, leaving the rust behind; like casting off an oversize glove.

Galvanised wire ties rust too. Once more due to poor zinc thickness. We have found worse corrosion than this on ties supplied and installed to builders as recently as the 1970’s. The worry with these is that the small section is rarely sufficient to cause expansion cracking – the first sign of a problem could be a bulging wall or worse.

Caution! This tie, inspected through a boroscope would class as reference level 5 using; visual grading of the condition of steel ties table in BRE 401. However, be careful; where black ash is present, as in this case, more severe corrosion is typical in the bed joint; hidden from the boroscope. Going by this image alone, a surveyor could be forgiven for marking this tie down for 5 year inspection……the following image reveals the full extent of the problem.

Removing a brick from the external leaf reveals the whole tie. Look closely; the section of tie in the cavity is quite free of rust – only a white ‘tell tale’ of zinc oxide indicates a problem. If aggressive mortar is suspected DO NOT us a boroscope as evidence that there is no significant corrosion problem. Checking the tie in the external leaf bed-joint is essential in this case.

Remember: The acidic effect of black ash mortar is mainly confined to the section of tie which is in intimate contact with it. If in doubt call Bryan for advice, or better still, book a survey.

“I hope the above gives you more confidence in boroscope inspections for wall tie defects. Please feel free to contact me if you have any further questions you’d like an answer to. And - please bear in mind that a boroscope is a dumb piece of equipment and in the hands of the inexperienced or untrained, it’s about as useful as a stethoscope is to a Plumber, or a blow torch is to a Doctor. We’ve been using this equipment every day since 1986 – if you need a boroscope inspection call us – and get accurate, properly interpreted results, which will save you time, worry and money”.