Thermal imaging for damp diagnosis

Is thermal imaging helpful for damp diagnosis?


Thermal image od damp wall in Leeds

The damp patches were there in the visible spectrum, but they really stand out in the infra red spectrum


This is a question I’ve thought about quite a bit over the past few years. Damp diagnosis is one of my passions so of course the prospect of another damp diagnostic ‘toy’ appealed to me.

However, at several thousand pounds for a half-decent model and bearing in mind the pitfalls associated with improper use of them, I set aside my desire and plodded on without one.

Still, I couldn’t help thinking “Is thermal imaging helpful for damp diagnosis?”


The thought wouldn’t go away. The only people saying that these cameras were good value were either selling them, or those who had bought one already and were apparently seeking to justify the investment. I noticed that many surveyors used them straight from the box, with nothing but the manual and a basic guide to help them get things right.

I knew that this was a risky policy, because some years ago I attended the Property Care Association’s one day course “An Introduction to building Thermography” which was excellent, but which made me realise that there’s more to a thermal imaging camera than pretty colours and lots of kudos.

Then my good chum Ross Charters intervened by introducing me to Stuart Holland of Thermographic Consultancy Limited.

I’d always said that I wouldn’t buy a camera without proper training and Ross had found just the man for that.

That was 7 months ago and now I am a category 1 thermographer and have a relatively high spec thermal imaging camera.

And I’ve been using it…….. a lot.

Is thermal imaging helpful for damp diagnosis?

Instant diagnosis via wireless connection from thermal camera to Hygrometer – the patch is less than 1C above dew point – why?

Thermal imaging in Yorkshire housing

The isotherm function helps us focus on the points of interest, where the wall is colder

Using thermography with mosture meters to diagnose damp

There are cold spots elsewhere in the house but these are dry – why?

As above and below, the images speak for themselves…. but when you dig into the thermograms and combine them with environmental data and moisture meter readings, they really sing:

So first thing first.

Am I glad I bought it?– YES

Do I fully understand it’s potential? – SORT OF

Is it helping my damp diagnosis? – SOMETIMES

Is it surprising me? – YES

Is it worth the thousands I paid? – YES

Was the training really necessary? YES

Is it helping me get my diagnosis over to clients? – YES YES YES

Rising damp or a leak in Bradford

That is a very damp wall – but is it rising damp, bridging or a leak?

Mould caused by disturbed insulation in Tadcaster

There is mould on this ceiling and now the Flir420bx shows us where the insulation is allowing cold air from the eves to blow under it.

Baffled PIV unit protecting the smoke alarm thermography

A typical Positive Input Ventilator in a ceiling, with correctly installed baffles protecting the smoke alarm (see spot 3).


Even from the monosyllabic  review above, you can see that mostly it’s all-positive. That’s because as a damp diagnosis tool it is just that, another tool in the bag to help get to the problem (or lack of).

I can link it wirelessly to my moisture meter, displaying RH% , dew point and Vp on screen, so that I can set up isotherms to highlight cold bridges, condensation traps and missing insulation instantly.

I don’t have to get stepladders out to find missing loft insulation – every time I have done that the trip into the loft has only confirmed what the camera told me. In fact, with practice I can now see whether the insulation is missing or just lifted slightly, so that cold air is blowing under it…. Ace.

In traditional buildings it helps me find hidden timber frames and members; bricked-up openings and leaks.

I did without the technology for years but now, I wouldn’t want to be without it. The main reason I say this is not because I hate climbing ladders – I still do that to check out the roof timbers for infestation and such. The icing on the cake is the way the technology allows me to illustrate issues for clients and tenants. It sits alongside the gravimetric and salt testing lab as a tool for communication, as much as for diagnosis.

In addition, the training involved going over and into thermodynamics, which was a revelation for me as I hadn’t really thought about it much since school. The need to keep abreast of it, has helped me hone my existing knowledge and understanding of moisture movement in buildings, which is governed by energy, as much as by gravity, porosity and hygroscopicity. Balancing these with reflectivity, emissivity and thermal movements like conduction and convection, sharpens understanding of the whole system.

poorly installed cavity wall insulation detected by thermal camera in Leeds

This Leeds house gable looks like it may have a patchy cavity wall insulation installation

Using building thermography to find missing cavity wall insulation in Yorkshire housing.

A closer look through the Flir420bx shows a potential void in the cavity wall insulation, as a warmer area

Inspecting cavity wallinsulation using thermography and a boroscope

Now a hole can be drilled and the void inspected by boroscope


Investigating a cavity wall using thermography and a boroscope in Yorkshire

The void turns out to be quite extensive

Boroscope inserted into insulated cavity

Where the cavity wall insulation is installed correctly – this is what should be seen in the cavity. The thermal imaging camera took me straight to the voids – so the house doesn’t need to look like a pin cushion.


Simple things underpin our lives and Stuart Holland’s thermography course, combined with regular use of the equipment, is making my professional life more productive and satisfying.


I still get a kick from being able to ‘see’ through walls though…. It tickles the boy inside me.

Thermal imaging is now used daily and I hope to trade-up for an even better unit in the next 12 months as my experience and expertise grows. No doubt my surveyors will need one soon…. after suitable training of course.

So “Is thermal imaging helpful for damp diagnosis?”

“Too right”.

Dry Rot.



  1. Hi Bryan,

    I couldn’t be without mine now. Glad I done the training with Stuart though,I actually sent him and you a thermal imaging report that was recently carried out on a building that was completely wrong. Did you get it?
    Keep up the good work 🙂

    • Ha,

      I read that report – couldn’t believe the findings. The images had no relation at all to the findings!!!!

      Crazy – just shows that being able to use a thermal imaging camera is no good if you don’t understand buildings and moisture.

      Keep the faith


  2. Bryan,

    Fantastic blog and great to see that it is a straight up honest report, pros and cons in exactly as you have found them. We find it sometimes difficult to convince those that are sceptical of the benefits, when we can sometime be consider the ‘sales men’. Obviously we are not, we are first and foremost thermal imaging consultants operate professionally in the field, that also sell FLIR thermal imaging equipment and provide expert training to grow the industry in the correct way.

    I know that the use of thermal imaging will keep you going from strength to strength, whilst also keeping you ahead of all your competition, which is the future of building inspection. Between yourself and Mr Charters, the services you provide are superb.

    Keep up the lab work. 🙂

    • Dry Rot says

      Thank you Stuart,

      The training and support you have provided is the essential ingredient, making sure that I can build my skill and knowledge on firm foundations.

      Now the weather is cold, it’s coming out of the bag on a daily basis; a great piece of kit!


    • John Lam says

      Dear All Fellow practitioner

      I am the Professional Building Surveyor practicing in Hong Kong . I am also the only few of the professional who has the passion and belief of using the infra-red scanning for damp checking . It will be glad if you all can let me know where I can receive the proper training on infra-red scanning for damp diagnosis.

      Interestingly, Hong Kong Professional does not welcome infra-red . I can see one of the reasons is lacking of training both in college and life-practicing . I have bought one FLIR E4 for my experimental interests . I also bought one moisture (wireless) meter from Extech.. I really hope to have a comprehensive understanding and knowledge on infra-red … Hoping all the fellow practitioner here can give me some insight


  3. This is fascinating. I live in Western Washington in the United States, where the rain is constant and damp is the norm. In all my years living here, though, I’ve never seen someone use thermal imaging to check for water damage. Frankly, your results are some of the most impressive I’ve ever seen. It’ll be hard to hire a contractor who doesn’t offer this kind of technology. Thanks so much for sharing.

    • Dry Rot says

      Thank you Cal and it’s great you took the time to post a comment 🙂

      Thermal imaging is another tool and can be great for diagnosis and for communication to clients. It’s a minefield for those who do not appreciate the technology though. This means it can be misused and abused too. My specialisation (amongst other things), is damp diagnosis. However I still had to attend a full week of training and pass a short exam to get a category 1 thermal imaging qualification. Well worth the effort because without a full appreciation of the tool, it may mislead the operator.

      All the best Cal


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