What’s broken about damp diagnosis in the UK

What’s broken?

Having listened carefully to the Blue Box seminar ‘shifting the paradigm’ I can say that yes, something about the housing market is broken; where damp is concerned and this was reflected in the presentation by Phil.

There was some gnashing of teeth in respect of all the ‘unnecessary’ damp proofing work which is done. The poor performance of guarantees and remedial work was mentioned too. As the only contractor in the room, I listened as ‘we’ were placed on the list of suspects in this shameful situation, along with:

The lenders
The surveyors
The estate agents
Us (the contractors)

Missing from the line up are:

The vendors
Trading Standards
The PCA (Property Care Association).

In a nutshell, it seems that there is a cycle of repeat damp proofing and remedial work which we are told is due to poor diagnosis, commercial greed of contractors and worthless guarantees.

I’d just like to float the contractors view about diagnosis if I may.

Damp diagnosis is rarely difficult and does not normally require a great deal of equipment. Whilst houses vary, many are built from very common materials using established methods. After a few years operating in any geographical area, a competent surveyor will enjoy a pretty good understanding of the materials and see that some houses are damp and some are not.

Bear in mind that as a damp specialist, I am not normally called in as a precaution; a RICS member has usually obtained high readings or otherwise been put on notice of a defect during his survey.

A decent moisture meter, combined with a good pair of eyes (Alas, I need my glasses to see woodworm holes now) is sufficient and if there is a clear rising damp profile, with no other defects which could explain the readings, then a damp proof course, may be needed. I say may be needed, because sometimes there is already one installed. In which case we have to consider what else could give a rising damp profile in a wall with a chemical DPC in it:

1. The DPC is not effective
2. The DPC is effective, but the plastering was never done or was done incorrectly.

Keep in mind that there are no other visible defects, so just for now forget high ground, bridging, condensation and such……

Now then, with no guarantee available, re-plastering properly is the answer – but, we still can’t tell if the DPC is working and if we merely plaster over it, the rising damp will eventually rise over the top of our plasterwork (lets assume the client doesn’t want to plaster to the ceiling). It could also be a threat to the skirting and timber floors too. So we need to put another DPC in to make sure we offer our client a guaranteed solution. The plastering work is a messy, disruptive and expensive item, so the cost of the DPC is very low in comparison.

Of course we could decide to really see if the DPC is working or not. This is easily done, but it is disruptive (so a vendor will not allow it), it takes a week or so and someone needs to pay us for this. The cost of taking a number of drill samples, weighing them, subjecting to 75% RH for a few days, drying them, weighing them, writing a report and such is normally at least as much as the DPC installation. We can get to the bottom of it and sometimes the DPC is working and bingo – we can re-plaster only. Or the DPC is, as suspected, not working and we’ve wasted our time and the client’s money.

Forget salt analysis – who cares if we have nitrates or chlorides? The wall is damp and the plaster is salty and any wall with a history of rising damp – cured, controlled or not, will have some salts in it. The tap water; used to mix the plaster with originally, will have maybe 50 parts per million nitrate (the limit is 30ppm, but we’re taking about old plaster). Our rising damp profile means that more salts have been added over the years, so what’s the point?

The fact is that in the vast majority of damp situation, a mobile laboratory is not required.

However, if there is a depute about the cause, further tests are needed. This is where much resentment and confusion arises. Let’s say that there is a Guarantee available for this DPC; with the rising damp profile.

Along comes Rising Damp-Away ltd to investigate. Why is he there? Well, because an explanation is needed. He is in the same position as I was on arrival but he knows that his DPC is working doesn’t he? Well, he has something we don’t, which is the context of the original job. Maybe he quoted for the re-plastering, but the owner wanted his brother-in-law to do it. He can quickly see if this has been done. Alternatively he may have done the re-plastering too, in which case he is flummoxed and worried and wants to get to the bottom of things. Without x-ray eyes he cannot tell if the DPC has failed or if the plastering is at fault. Either way he is in trouble, so often, in these cases, a savvy contractor will just re-install and re-plaster with good grace (the only way to preserve some goodwill – do things grudgingly and you’re hated for it).

However, if the job is a really big one, the DPC may be worth saving, if it’s just a plastering error. Or, if the client is a monster and is trying to roast the contractor for inflated consequential losses – or if he just wants to get to the bottom of things so that he can improve quality in future, he will reach for the laboratory.

Some surveyors’ are implying that because contractors sometimes resort to the ‘in depth’ approach on DPC re-visits; this implies that an electrical moisture meter is not good enough for damp diagnosis generally. A Protimeter, in the hands of a trained and experienced surveyor is as useful as a stethoscope is to a doctor. It is nearly always all that is needed. Think of gravimetric testing and hygroscopic moisture content separation as our equivalent to the doctor reaching for the MRI or CAT scanner. Doctors listen to my heart and breathing, look at my tongue, take a quick blood pressure test, then tell me to stop worrying.

If a doctor called for scans, x-rays, blood tests and biopsies, every time a patient turned up with fever he’d be sacked. It would be wasteful of time and money and would normally return the same diagnosis that Dr Finnley made with his stethoscope.

Any trained surveyor can complete a damp survey – using ‘standard’ equipment. RICS can do this and I’d be happy to help. Good contractors can do this too. Very specialised independent surveyors can too, but don’t forget that they do not need to do anything additional to reach a diagnosis – in the vast majority of cases.

This cycle of repeated damp proofing work is not caused by the contractors. It is merely a result of poor guarantees which do not generally have robust insurance cover. The GPI scheme is the leading and most effective way of breaking this negative cycle, combined with good training and effective treatment provided by PCA members.

If, lenders and surveyors simply rejected a big fraction of the absolute rubbish damp reports, issued by unqualified, none member companies and individuals, then PCA membership would have to rise, bringing more contractors into better training, better quality auditing and better insurance. As things stand a contractor only has to be able to spell ‘specialist’, in his yellow pages advert and he is one. The lenders and surveyors could stop this.


Speak Your Mind


Copyright © 2010 Preservation Expert. Legal Stuff: All the advice and information in the posts on my blog is made in good faith and is based on my experience and knowledge at the time of writing. However, nobody is infallible and whilst I’m confident that most of what I write about preservation issues is accurate, there’s a good chance there’ll be an error or two somewhere. I do change my mind about stuff, as I gain more experience. In view of this you must make your own decisions on whether to follow any advice I write and think about this; I could be wrong. No responsibility will be accepted by the author for any losses anyone may suffer as a result of any mistake or for the consequence of any action you take as a result of reading this blog. If you do suffer a loss, resulting from anything I’ve written, a verbal heartfelt apology will be your only compensation.