Diary of a dissatisfied customer
 
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Thermography (Thermography Results and Endoscope Results)
 
This section is divided into two parts. The same principle is used as seen in the problem section where each additional page links back only to this main page. Organisation of the pages is as follows:
  • Thermography (this page) is a general introduction and may be useful to others contemplating exploration of cavity wall insulation (CWI) issues, and indeed other thermography needs such as tracing leaks on underfloor heating. There is clearly a new business opportunity awaiting someone on this subject in relation to the booming energy conservation industry. If I was younger I would be marching into this fascinating technology but as it is I am already surrounded by heaps of interesting technology which keeps me busy.
  • Endoscope random images. I already own a Rothenberger Rocam (video) and it occurred to me to drop this down the cavity in the unsleeved meter cupboard. I could see straight to the bottom (over one metre) where I can vaguely see a tool someone has dropped in the past. Hence there is a void. I have devised ways to explore elsewhere using my own endoscope which will capture still images and movie of any voids: The Rocam equipment is unsuited to CWI needs owing to glare from IR lighting, being better suited to pipework and drainage investigations.
  • Thermography results. As the name suggests this page will be devoted to the thermographic images, good or bad. I already know of two voids but I would not consider that unmanageable from a remedial perspective. The work must be corrected (I paid for it) but if major upheaval can be avoided, so much the better.
You can hire thermographic equipment but you also need to hire expertise unless you happen to have experience, which I certainly do not. For an external survey it is clear from speaking to several experts on the subject that there needs to be a temperature differential between internal areas and the external air. A subject I will be discussing elsewhere in due course, not connected with this saga or to use a more appropriate expression coined by a journalist recently, industrialised deceit.

Thermography for assessing CWI demands the following:

  • A cold day
  • A dry day
  • An overcast day (no sun)

That will usually mean an early start on the day for which the householder needs to be equally prepared, long before the survey date and on the survey date. The following is a must:

  • Heating on constant for 24 hours before the survey and I would suggest longer if the property has been empty for some time. A base rate of 21 degrees is a good starting point. Open all TRVs (Thermostatic Radiator Valves) fully. Get all radiators heated.
  • All internal household doors open and windows shut.
  • Any large items of furniture moved away from external walls if possible. If you have built-in wardrobes against an outside wall, empty the wardrobes and leave the doors open. Beds and sofas against any external wall. Anything at all that might artificially insulate a wall, including room height curtains or, in some cases, kitchen units (open doors).
  • In my case I am removing the bath panel to allow free circulation of air. I am a believer in insulating under baths for reasons which will be discussed elsewhere. I recommend use of itch-free insulation (Note 1) which is a dream to work with and is available from many well known DIY sources.
  • Screen off any fireplace to stop heat escaping up the chimney. A piece of hardboard or cardboard better than nothing.
  • Curb use of fans if possible. In short, if heat is to escape it ideally needs to be trying to do so through your walls as evenly as possible.
  • There is no need to block natural draught ventilators required as air-for-combustion ventilators. They will show up as a useful contrast.

I am fortunate that my wet central heating strategy employs radiators on internal walls, a long way from external walls. Leaving the radiators on cannot distort temperatures detected on any area of wall.

It should be remembered that my cavity wall insulation was installed a long time before I discovered a serious void. It never occurred to me there might be any cause for concern. Given the void has no obvious cause, which I am well qualified to judge, I decided to investigate. I would not encourage anyone to invest in thermography, which is not ordinarily cheap, unless they have good information to suggest there is a problem such as voids.

If there are issues, contact the installation company first but keep everything in writing no matter what the pressure to agree to meetings. If you really must have meetings record them, but tell them you will do so. If you feel vulnerable have someone else present, then there is less chance of harrassment and bullying that you must assume will be inevitable. Do not use the telephone under any circumstances unless you have recording apparatus like my truecall (Note 2) system. Assume the people working for these companies are desperately trying to impress their line-managers, not customers. Bullying is often endemic within large organisations as well and that can rub off. Arm's length management is the order of the day.

That said, there may be other options for detecting a CWI problem initially. Details possibly applicable to others may be found on the Endoscope random images page of this section. The techniques involved include intrusive surveys so again, unless you have genuine reason to be concerned, I could not suggest damaging your property in the process.

I know one Chartered Surveyor who has said he believes blown-in mineral-wool CWI can 'settle' because he invariable notes the absence of cavity fill at eaves level when working on buildings alleged to have had CWI. I do not agree. The mineral-wool is far too light and fluffy, the cavity too narrow, the fricton too great and there is an absence of movement of the structure. Different of course for an economy size pack of washing powder which is heavy, the cavity (box) wide, the friction negligible and with all the movement, the contents rapidly settle. The box expands at the waist slightly each time it is put down: If the mineral-wool is absent then you can safely assume it was never there.

 
 
I saw some mineral wool at eaves level when I was renewing soffits and facias. Some of it 'splashed' onto roof spars. Some could be seen down the cavity. The work was leisurely as I had a full scaffold, therefore there was ample time to inspect the cavities in complete safety. The insulation seen in the image on the left was being introduced over window heads to eliminate thermal bridges.

As a contrast we have seen extraordinary finds of polystyrene beads or granules under ground floors where they have escaped around joists. An associate of mine reported one case where there was 'enough to fill a builders' bag'.

Because of its 'fluffy' characteristics mineral wool is 'sticky' like cotton-wool brushed across morning-after stubble. It is like the itch-inducing fibreglass which seems to stick to everything, although mineral-wool does not have the unpleasant feel of fibreglass as it is less coarse.

Beads and granules tend to be more 'liquid' and free to flow where needed. I certainly know what I would use in future given the questionable reliability of the blown-in mineral-wool process. More on this subject in the analysis section.

 
NB: This page was edited 24.02.2013. There were three parts proposed to this section but only two have proved necessary. The proposed third part has been deleted as the subject matter has been resolved in the second part.
 
 
  • Note 1: I have no connection directly or indirectly with any companies linked to as examples on this website.
  • Note 2: This system enables you to screen out and/or block unwanted callers 100%