Serving the greater Auckland Area since 1988
Once you have realised you might need some kind of investigation because you suspect (or know) there are problems, the first thing you do is some background research - which is why you are here. Having read (or at least skimmed) through these pages, you will (hopefully) decide to contact a consultant via email or phone. This initiates the process described below (in this case for a typical weathertightness survey)
The consultant will arrive on time (hopefully) armed with the necessary equipment. He should know by now what is required. Which brings us to a brief discussion of what tools are useful when undertaking weathertightness surveys in particular. Those listed below may not all be used. The first couple are totally non - invasive (don't damage wall linings - or anything else), below that they get progressively more intrusive
A non invasive meter.
There is quite a range available. I mostly use a Trotec T 600 which is a Microwave unit, I also have an (older) Humitest MC 50 which does not "read" nearly as far (deep into the wall framing). All such units have limitations which not everyone seems to appreciate. They are basically just "indicators" - if they give a high reading, that means a bit of thought (and experience) is needed to decide what significance, if any, to attach to it. Frequently such elevated readings do mean further investigation is needed.
Infrared Thermal Imaging.
This is a fast growing and much talked about technology. Unfortunately the cameras still cost a great deal of money which means anyone who buys one has invested a lot of capital and is thus highly motivated to recover it and may (therefore, possibly) overstate its value. The concept is very simple - the camera shows temperature differences as variations in colour on the screen (which can be printed out). Cold areas may be wet areas. Of course, there are plenty of other possible reasons why there might be differences in temperature on an outside wall besides water. Time of day and year is obviously important. Very useful tools, in the hands of an experienced operator, for identifying areas which require further explanation / investigation. By no means the ultimate or only tool for diagnosing weathertightnes. The best operators team up with building surveyors.
An Auckland company has a patent on a small object that gets inserted into a hole drilled in your skirting board - usually at least alongside doors and under the corners of windows. This is about 10 mm in diameter and when fitted looks exactly like a shirt button. The two little dots are the ends of stainless steel wires which now go almost right through your wall and stop about 5 mm shy of the outside face of the wall frame. As moisture usuall starts entering from the outside, the outside face of the frame is the best place to start looking. Once they are installed, it is a simple matter to hold a resistance meter up to them and obtain a (fairly) accurate reading of the moisture content of the framing at the most vulnerable point - just where the cladding is fixed to it. This reading is the same as has been traditionally obtained by surveyors by drilling through the cladding. A couple more useful bits of information are obtained when drilling from the inside like this:
The shavings may also be tested in a laboratory for traces of treatment and/or fungal activity. I like these probes - you get quite a lot of information without having to drill lots of holes through the cladding. However, like the thermal imaging camera, not a complete answer.
Having carried out one or more of the preliminary surveys described above, the surveyor now studies the results in conjunction with the plans and specifications. There are inevitably areas of risk none of the techniques so far described will have been able to canvas. And of course those preliminary surveys may easily have identified problem areas which now need further investigation. The reality is all houses leak. What you are paying the consultant to do is to figure out what damage these inevitable leaks may have caused - or may cause in the future - so he can figure out what to do about it.
To this end, where justified, the consultant will start drilling holes through the cladding, although (hopefully) not without having discussed this with you fully. Personally, I don't like doing this unless I am fairly certain there is a problem. This is even more true of the next stage, which is cutting out sections of cladding to expose the framing. This is done to expose poor quality construction details and/or actual damage (decayed framing) and is essential if evidence is being collected for a dispute tribunal of any sort. As above, not to be undertaken lightly and the sign of a good surveyor is if every cut out exposes something that is going to be extremely useful down the track to you, the client.
See this page for an example of a useful cut out which also illustrates an important point about accurate moisture content readings - they too can be misleading.
Having collected the evidence, this is now put down on paper, hopefully in a logical, coherent manner that is readily comprehensible to anyone who needs to read it. The form it takes will have been set out in that initial brief and agreed to in the contract you signed. It is important to understand there is a significant difference between the two parties that spend most time perusing these reports: surveyors (experts) and lawyers. If you hire a lawyer, to a large extent you "own" him (or her). This person is quite literally your advocate - speaking for you, with your best interests uppermost in their mind. Or so we hope. The surveyor, on the other hand, if preparing a report for a dispute hearing of any kind is in a different position. The expert's primary duty is to that Tribunal, not to you. There is a Code of Conduct governing the behaviour of Expert Witnesses - and when placed in this position, the expert is bound to be impartial, not your advocate. You can't hope for much of a bias in your favour in the report - the surveyor is bound to tell the Truth. However, it is not always necessary to put all the evidence that has been collected into the report.
Depending on the brief that has been agreed to, the report may then move onto describing what needs to be done to bring the house into compliance with the building code. See Remediation pathway for a description of this process.