Rising damp, penetrating damp or salt contamination? Why is that wall damp?
Rising damp or not ?
A month of so back I had the great pleasure of Graham Coleman’s company for two days here in Yorkshire. Regular visitors will know Graham, from past posts which he either contributed or featured in. For those that don’t know Graham, he is the Chief examiner for the Property Care Association; a career scientist with particular skill and knowledge of damp diagnosis and timber infestations. He’s the damp proofing industry’s technical guru…
He’s also become a good friend, as we have so much in common and he’s great fun to be with. Graham offered to come to Leeds, to spend time in my new gravimetric testing and salt analysis lab, which was set up with his help. Whilst this testing is not rocket science (nothing in damp diagnosis is), it is a little more complicated than normal and using a big chemistry set to search for ground salts in masonry and separate out hygroscopic moisture from capillary moisture is not something I do every day. (Graham’s been doing it for decades).
Nitric acid used to check the chloride result
Our first session was spent extracting salts from plaster and masonry samples for testing and then using the chemicals in the lab, to cause reactions, which indicate the nature of the salts present (if any). There are test strips and such, including tablet test kits but these tend not to be as accurate and I wanted to see the reactions for myself, to gain full understanding of the techniques described in past technical papers.
This went well and Nitrate’s and Chlorides were detected to various levels in some of the samples. This was expected because my work with gravimetric testing of these samples earlier in the month (see this recent post on this method of damp diagnosis) had indicated that some had high hygroscopic moisture present. As hygroscopic levels were high, this implied contamination, but the salts testing Graham has schooled me in sealed the deal and confirmed the suspicions…. Great stuff.
A milky precipitate indicates chlorides are present
Why bother? Well there are times when a damp situation needs to be dissected down into the components of the moisture, so that the source of the damp, which may have been indicated with visible or moisture profile work, can be further refined. It’s a great additional tool for me and my customers. Rising damp, penetrating damp and condensation usually look different (see my very basic guides on damp here, here and here), but sometimes these may overlap or there could be a dispute and more accuracy is called for.
Bryan and Graham in the damp diagnosis lab
Later sessions included spread sheet work, to produce workable data sets from the damp readings; separating ‘free water’, such as rising damp, from the salt derived hygroscopic moisture, and develop graphs to help clients understand the data too.
Some computer work to compile a damp report based on the lab work (notice Bryan’s dad watching over things from the right)
The combined techniques of gravimetric damp testing, to establish moisture profiles, along with salt analysis is the most powerful tool available in accurate damp proofing diagnosis. Though it is just a tool and needs to be combined with on-site visual inspections and a good knowledge of damp in buildings and building technology. As a damp proofing specialist it also helps me to check my own damp survey findings, against the lab results. Fortunately so far, the gravimetric damp testing has confirmed my conclusion reached on site during damp surveys, which is some comfort but, actually I am looking forward to getting ‘caught out’ it’s the best way to learn.
I must stress that anyone using this method should always profile the wall in question and take control samples from unaffected areas too. ‘One off’ sampling using this method or a carbide meter is prone to mislead.
My thanks go to Graham Coleman for his great generosity in sharing his many years of experience. He’s an honorary member of the Property Care Association, which is a well deserved tribute to such an important contributor to the knowledge of scores of PCA members, their staff and the care of our customers in turn.
Enthusiastic damp diagnosis, backed by real expertise
Please visit Graham’s web site and contact him for training services and damp and timber consultancy.
Dry Rot.
For advanced damp diagnosis in Yorkshire please visit my main web site below, where you can check out my little firm. We can help with damp proofing, woodworm, wet rot dry rot and all damp related building defects. All my staff are highly qualified and as enthusiastic as I am, so do please check us out.
WWW.BTPRESERVATION.CO.UK
Hi Bryan, I have only been pointed at your web site and must congratulate you on the presentation adn detail.
Like you I am very enthusiastic is raising the standards in the industry and expanding public awareness.
I have not had the chance to look through all of the content on your site but will do so over the next couple of days and will give you some feed back. First impressions though are very good.
Thank you for looking in Neil,
It’s always good to get feedback on posts so that i know what people are interested in and can refine my communications for them.
You’ll see that the tone varies because sometimes I write for surveyors and surveying students. Other posts are aimed at lay people and consumers, with no prior knowledge, just wanting basic advice, so I try to keep it simple.
I see that you are a member of the PCA – nice one; PCA membership is so useful for consumers in beng able to sort the wheat from the chaf, when looking for a qualified and pre-vetted specialist company.
Do please let me have any feedback, good or bad; that way I can hopefully improve.
best regards
Dry Rot.
Hi Bryan,
Another useful and interesting write-up !
Thank you !
I have tended to use the Protimeter tablets for testing for the presence of Nitrates and Chlorides myself to date if I have needed but have never been 100% happy with its results.
I did have another test kit to trial but it was for Nitrates only and this showed its results in parts per million measurements so was a little more accurate than the Protimeter version but I have never found a suitable alternative test kit for the Chlorides testing.
Is there alot to consider in setting up a similar system to yours for testing as Graham had helped you to arrange?
Kind regards
Dave Taylor
Hi David,
Thank you for the encouragement. With reference to Nitrates and parts per million. Don’t get too hung up about accuracy of measurement. What matters is the relative amounts not the exact amounts. You are looking for the distribution of salts in the wall and not the actual content.
if ther are levels of chloride or Nitrates concentrated in for example – a salt band; how di that arise? The salts were not there when the house or wall was built. It doesn’t matter whether there are 800ppm, 8000ppm ot 880ppm. By looking at the relative differences in in concentration you can see where evaporation took place and deduce where the water which carried the salts came from. So the testing method can be qualitative and provided the testing method is consistent you’re fine.
Bryan